Changing the enable/disable sequence in commit c9b1150a68d9 ("drm/atomic-helper: Re-order bridge chain pre-enable and post-disable") has caused regressions on multiple platforms: R-Car, MCDE, Rockchip.
This is an alternate series to Linus' series:
https://lore.kernel.org/all/20251202-mcde-drm-regression-thirdfix-v6-0-f1bff...
This series first reverts the original commit and reverts a fix for mediatek which is no longer needed. It then exposes helper functions from DRM core, and finally implements the new sequence only in the tidss driver.
There is one more fix in upstream for the original commit, commit 5d91394f2361 ("drm/exynos: fimd: Guard display clock control with runtime PM calls"), but I have not reverted that one as it looks like a valid patch in its own.
I added Cc stable v6.17+ to all patches, but I didn't add Fixes tags, as I wasn't sure what should they point to. But I could perhaps add Fixes: <original commit> to all of these.
Signed-off-by: Tomi Valkeinen tomi.valkeinen@ideasonboard.com --- Linus Walleij (1): drm/atomic-helper: Export and namespace some functions
Tomi Valkeinen (3): Revert "drm/atomic-helper: Re-order bridge chain pre-enable and post-disable" Revert "drm/mediatek: dsi: Fix DSI host and panel bridge pre-enable order" drm/tidss: Fix enable/disable order
drivers/gpu/drm/drm_atomic_helper.c | 122 ++++++++++++++---- drivers/gpu/drm/mediatek/mtk_dsi.c | 6 - drivers/gpu/drm/tidss/tidss_kms.c | 30 ++++- include/drm/drm_atomic_helper.h | 22 ++++ include/drm/drm_bridge.h | 249 ++++++++++-------------------------- 5 files changed, 214 insertions(+), 215 deletions(-) --- base-commit: 88e721ab978a86426aa08da520de77430fa7bb84 change-id: 20251205-drm-seq-fix-b4ed1f56604b
Best regards,
On Sun, Dec 14, 2025 at 1:42 PM Tomi Valkeinen tomi.valkeinen@ideasonboard.com wrote:
Should we merge this series as a fix for 6.18 rcs?
Too late now, so let's merge it as a fix for v6.19 rcs!
Ah, right. Indeed, I meant v6.19 rcs.
Are you applying it or should I? Not sure if you want some special timing, like outside of holidays.
Yours, Linus Walleij
Hi,
On 23/12/2025 01:18, Linus Walleij wrote:
On Sun, Dec 14, 2025 at 1:42 PM Tomi Valkeinen tomi.valkeinen@ideasonboard.com wrote:
Should we merge this series as a fix for 6.18 rcs?
Too late now, so let's merge it as a fix for v6.19 rcs!
Ah, right. Indeed, I meant v6.19 rcs.
Are you applying it or should I? Not sure if you want some special timing, like outside of holidays.
Oh. No, I'm not a DRM maintainer, so I was waiting for someone to merge this. From my point of view it's ready for merging.
Tomi
This reverts commit c9b1150a68d9362a0827609fc0dc1664c0d8bfe1.
Changing the enable/disable sequence has caused regressions on multiple platforms: R-Car, MCDE, Rockchip. A series (see link below) was sent to fix these, but it was decided that it's better to revert the original patch and change the enable/disable sequence only in the tidss driver.
Reverting this commit breaks tidss's DSI and OLDI outputs, which will be fixed in the following commits.
Signed-off-by: Tomi Valkeinen tomi.valkeinen@ideasonboard.com Link: https://lore.kernel.org/all/20251202-mcde-drm-regression-thirdfix-v6-0-f1bff... Fixes: c9b1150a68d9 ("drm/atomic-helper: Re-order bridge chain pre-enable and post-disable") Cc: stable@vger.kernel.org # v6.17+ --- drivers/gpu/drm/drm_atomic_helper.c | 8 +- include/drm/drm_bridge.h | 249 ++++++++++-------------------------- 2 files changed, 70 insertions(+), 187 deletions(-)
diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c index 10adac9397cf..ef97f37560b2 100644 --- a/drivers/gpu/drm/drm_atomic_helper.c +++ b/drivers/gpu/drm/drm_atomic_helper.c @@ -1341,9 +1341,9 @@ disable_outputs(struct drm_device *dev, struct drm_atomic_state *state) { encoder_bridge_disable(dev, state);
- crtc_disable(dev, state); - encoder_bridge_post_disable(dev, state); + + crtc_disable(dev, state); }
/** @@ -1682,10 +1682,10 @@ encoder_bridge_enable(struct drm_device *dev, struct drm_atomic_state *state) void drm_atomic_helper_commit_modeset_enables(struct drm_device *dev, struct drm_atomic_state *state) { - encoder_bridge_pre_enable(dev, state); - crtc_enable(dev, state);
+ encoder_bridge_pre_enable(dev, state); + encoder_bridge_enable(dev, state);
drm_atomic_helper_commit_writebacks(dev, state); diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h index 0ff7ab4aa868..dbafe136833f 100644 --- a/include/drm/drm_bridge.h +++ b/include/drm/drm_bridge.h @@ -176,33 +176,17 @@ struct drm_bridge_funcs { /** * @disable: * - * The @disable callback should disable the bridge. + * This callback should disable the bridge. It is called right before + * the preceding element in the display pipe is disabled. If the + * preceding element is a bridge this means it's called before that + * bridge's @disable vfunc. If the preceding element is a &drm_encoder + * it's called right before the &drm_encoder_helper_funcs.disable, + * &drm_encoder_helper_funcs.prepare or &drm_encoder_helper_funcs.dpms + * hook. * * The bridge can assume that the display pipe (i.e. clocks and timing * signals) feeding it is still running when this callback is called. * - * - * If the preceding element is a &drm_bridge, then this is called before - * that bridge is disabled via one of: - * - * - &drm_bridge_funcs.disable - * - &drm_bridge_funcs.atomic_disable - * - * If the preceding element of the bridge is a display controller, then - * this callback is called before the encoder is disabled via one of: - * - * - &drm_encoder_helper_funcs.atomic_disable - * - &drm_encoder_helper_funcs.prepare - * - &drm_encoder_helper_funcs.disable - * - &drm_encoder_helper_funcs.dpms - * - * and the CRTC is disabled via one of: - * - * - &drm_crtc_helper_funcs.prepare - * - &drm_crtc_helper_funcs.atomic_disable - * - &drm_crtc_helper_funcs.disable - * - &drm_crtc_helper_funcs.dpms. - * * The @disable callback is optional. * * NOTE: @@ -215,34 +199,17 @@ struct drm_bridge_funcs { /** * @post_disable: * - * The bridge must assume that the display pipe (i.e. clocks and timing - * signals) feeding this bridge is no longer running when the - * @post_disable is called. + * This callback should disable the bridge. It is called right after the + * preceding element in the display pipe is disabled. If the preceding + * element is a bridge this means it's called after that bridge's + * @post_disable function. If the preceding element is a &drm_encoder + * it's called right after the encoder's + * &drm_encoder_helper_funcs.disable, &drm_encoder_helper_funcs.prepare + * or &drm_encoder_helper_funcs.dpms hook. * - * This callback should perform all the actions required by the hardware - * after it has stopped receiving signals from the preceding element. - * - * If the preceding element is a &drm_bridge, then this is called after - * that bridge is post-disabled (unless marked otherwise by the - * @pre_enable_prev_first flag) via one of: - * - * - &drm_bridge_funcs.post_disable - * - &drm_bridge_funcs.atomic_post_disable - * - * If the preceding element of the bridge is a display controller, then - * this callback is called after the encoder is disabled via one of: - * - * - &drm_encoder_helper_funcs.atomic_disable - * - &drm_encoder_helper_funcs.prepare - * - &drm_encoder_helper_funcs.disable - * - &drm_encoder_helper_funcs.dpms - * - * and the CRTC is disabled via one of: - * - * - &drm_crtc_helper_funcs.prepare - * - &drm_crtc_helper_funcs.atomic_disable - * - &drm_crtc_helper_funcs.disable - * - &drm_crtc_helper_funcs.dpms + * The bridge must assume that the display pipe (i.e. clocks and timing + * signals) feeding it is no longer running when this callback is + * called. * * The @post_disable callback is optional. * @@ -285,30 +252,18 @@ struct drm_bridge_funcs { /** * @pre_enable: * - * The display pipe (i.e. clocks and timing signals) feeding this bridge - * will not yet be running when the @pre_enable is called. - * - * This callback should perform all the necessary actions to prepare the - * bridge to accept signals from the preceding element. - * - * If the preceding element is a &drm_bridge, then this is called before - * that bridge is pre-enabled (unless marked otherwise by - * @pre_enable_prev_first flag) via one of: - * - * - &drm_bridge_funcs.pre_enable - * - &drm_bridge_funcs.atomic_pre_enable - * - * If the preceding element of the bridge is a display controller, then - * this callback is called before the CRTC is enabled via one of: - * - * - &drm_crtc_helper_funcs.atomic_enable - * - &drm_crtc_helper_funcs.commit - * - * and the encoder is enabled via one of: + * This callback should enable the bridge. It is called right before + * the preceding element in the display pipe is enabled. If the + * preceding element is a bridge this means it's called before that + * bridge's @pre_enable function. If the preceding element is a + * &drm_encoder it's called right before the encoder's + * &drm_encoder_helper_funcs.enable, &drm_encoder_helper_funcs.commit or + * &drm_encoder_helper_funcs.dpms hook. * - * - &drm_encoder_helper_funcs.atomic_enable - * - &drm_encoder_helper_funcs.enable - * - &drm_encoder_helper_funcs.commit + * The display pipe (i.e. clocks and timing signals) feeding this bridge + * will not yet be running when this callback is called. The bridge must + * not enable the display link feeding the next bridge in the chain (if + * there is one) when this callback is called. * * The @pre_enable callback is optional. * @@ -322,31 +277,19 @@ struct drm_bridge_funcs { /** * @enable: * - * The @enable callback should enable the bridge. + * This callback should enable the bridge. It is called right after + * the preceding element in the display pipe is enabled. If the + * preceding element is a bridge this means it's called after that + * bridge's @enable function. If the preceding element is a + * &drm_encoder it's called right after the encoder's + * &drm_encoder_helper_funcs.enable, &drm_encoder_helper_funcs.commit or + * &drm_encoder_helper_funcs.dpms hook. * * The bridge can assume that the display pipe (i.e. clocks and timing * signals) feeding it is running when this callback is called. This * callback must enable the display link feeding the next bridge in the * chain if there is one. * - * If the preceding element is a &drm_bridge, then this is called after - * that bridge is enabled via one of: - * - * - &drm_bridge_funcs.enable - * - &drm_bridge_funcs.atomic_enable - * - * If the preceding element of the bridge is a display controller, then - * this callback is called after the CRTC is enabled via one of: - * - * - &drm_crtc_helper_funcs.atomic_enable - * - &drm_crtc_helper_funcs.commit - * - * and the encoder is enabled via one of: - * - * - &drm_encoder_helper_funcs.atomic_enable - * - &drm_encoder_helper_funcs.enable - * - drm_encoder_helper_funcs.commit - * * The @enable callback is optional. * * NOTE: @@ -359,30 +302,17 @@ struct drm_bridge_funcs { /** * @atomic_pre_enable: * - * The display pipe (i.e. clocks and timing signals) feeding this bridge - * will not yet be running when the @atomic_pre_enable is called. - * - * This callback should perform all the necessary actions to prepare the - * bridge to accept signals from the preceding element. - * - * If the preceding element is a &drm_bridge, then this is called before - * that bridge is pre-enabled (unless marked otherwise by - * @pre_enable_prev_first flag) via one of: - * - * - &drm_bridge_funcs.pre_enable - * - &drm_bridge_funcs.atomic_pre_enable + * This callback should enable the bridge. It is called right before + * the preceding element in the display pipe is enabled. If the + * preceding element is a bridge this means it's called before that + * bridge's @atomic_pre_enable or @pre_enable function. If the preceding + * element is a &drm_encoder it's called right before the encoder's + * &drm_encoder_helper_funcs.atomic_enable hook. * - * If the preceding element of the bridge is a display controller, then - * this callback is called before the CRTC is enabled via one of: - * - * - &drm_crtc_helper_funcs.atomic_enable - * - &drm_crtc_helper_funcs.commit - * - * and the encoder is enabled via one of: - * - * - &drm_encoder_helper_funcs.atomic_enable - * - &drm_encoder_helper_funcs.enable - * - &drm_encoder_helper_funcs.commit + * The display pipe (i.e. clocks and timing signals) feeding this bridge + * will not yet be running when this callback is called. The bridge must + * not enable the display link feeding the next bridge in the chain (if + * there is one) when this callback is called. * * The @atomic_pre_enable callback is optional. */ @@ -392,31 +322,18 @@ struct drm_bridge_funcs { /** * @atomic_enable: * - * The @atomic_enable callback should enable the bridge. + * This callback should enable the bridge. It is called right after + * the preceding element in the display pipe is enabled. If the + * preceding element is a bridge this means it's called after that + * bridge's @atomic_enable or @enable function. If the preceding element + * is a &drm_encoder it's called right after the encoder's + * &drm_encoder_helper_funcs.atomic_enable hook. * * The bridge can assume that the display pipe (i.e. clocks and timing * signals) feeding it is running when this callback is called. This * callback must enable the display link feeding the next bridge in the * chain if there is one. * - * If the preceding element is a &drm_bridge, then this is called after - * that bridge is enabled via one of: - * - * - &drm_bridge_funcs.enable - * - &drm_bridge_funcs.atomic_enable - * - * If the preceding element of the bridge is a display controller, then - * this callback is called after the CRTC is enabled via one of: - * - * - &drm_crtc_helper_funcs.atomic_enable - * - &drm_crtc_helper_funcs.commit - * - * and the encoder is enabled via one of: - * - * - &drm_encoder_helper_funcs.atomic_enable - * - &drm_encoder_helper_funcs.enable - * - drm_encoder_helper_funcs.commit - * * The @atomic_enable callback is optional. */ void (*atomic_enable)(struct drm_bridge *bridge, @@ -424,32 +341,16 @@ struct drm_bridge_funcs { /** * @atomic_disable: * - * The @atomic_disable callback should disable the bridge. + * This callback should disable the bridge. It is called right before + * the preceding element in the display pipe is disabled. If the + * preceding element is a bridge this means it's called before that + * bridge's @atomic_disable or @disable vfunc. If the preceding element + * is a &drm_encoder it's called right before the + * &drm_encoder_helper_funcs.atomic_disable hook. * * The bridge can assume that the display pipe (i.e. clocks and timing * signals) feeding it is still running when this callback is called. * - * If the preceding element is a &drm_bridge, then this is called before - * that bridge is disabled via one of: - * - * - &drm_bridge_funcs.disable - * - &drm_bridge_funcs.atomic_disable - * - * If the preceding element of the bridge is a display controller, then - * this callback is called before the encoder is disabled via one of: - * - * - &drm_encoder_helper_funcs.atomic_disable - * - &drm_encoder_helper_funcs.prepare - * - &drm_encoder_helper_funcs.disable - * - &drm_encoder_helper_funcs.dpms - * - * and the CRTC is disabled via one of: - * - * - &drm_crtc_helper_funcs.prepare - * - &drm_crtc_helper_funcs.atomic_disable - * - &drm_crtc_helper_funcs.disable - * - &drm_crtc_helper_funcs.dpms. - * * The @atomic_disable callback is optional. */ void (*atomic_disable)(struct drm_bridge *bridge, @@ -458,34 +359,16 @@ struct drm_bridge_funcs { /** * @atomic_post_disable: * - * The bridge must assume that the display pipe (i.e. clocks and timing - * signals) feeding this bridge is no longer running when the - * @atomic_post_disable is called. - * - * This callback should perform all the actions required by the hardware - * after it has stopped receiving signals from the preceding element. + * This callback should disable the bridge. It is called right after the + * preceding element in the display pipe is disabled. If the preceding + * element is a bridge this means it's called after that bridge's + * @atomic_post_disable or @post_disable function. If the preceding + * element is a &drm_encoder it's called right after the encoder's + * &drm_encoder_helper_funcs.atomic_disable hook. * - * If the preceding element is a &drm_bridge, then this is called after - * that bridge is post-disabled (unless marked otherwise by the - * @pre_enable_prev_first flag) via one of: - * - * - &drm_bridge_funcs.post_disable - * - &drm_bridge_funcs.atomic_post_disable - * - * If the preceding element of the bridge is a display controller, then - * this callback is called after the encoder is disabled via one of: - * - * - &drm_encoder_helper_funcs.atomic_disable - * - &drm_encoder_helper_funcs.prepare - * - &drm_encoder_helper_funcs.disable - * - &drm_encoder_helper_funcs.dpms - * - * and the CRTC is disabled via one of: - * - * - &drm_crtc_helper_funcs.prepare - * - &drm_crtc_helper_funcs.atomic_disable - * - &drm_crtc_helper_funcs.disable - * - &drm_crtc_helper_funcs.dpms + * The bridge must assume that the display pipe (i.e. clocks and timing + * signals) feeding it is no longer running when this callback is + * called. * * The @atomic_post_disable callback is optional. */
This reverts commit f5b1819193667bf62c3c99d3921b9429997a14b2.
As the original commit (c9b1150a68d9 ("drm/atomic-helper: Re-order bridge chain pre-enable and post-disable")) causing the issue has been reverted, let's revert the fix for mediatek.
Signed-off-by: Tomi Valkeinen tomi.valkeinen@ideasonboard.com Cc: stable@vger.kernel.org # v6.17+ --- drivers/gpu/drm/mediatek/mtk_dsi.c | 6 ------ 1 file changed, 6 deletions(-)
diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c index 0e2bcd5f67b7..d7726091819c 100644 --- a/drivers/gpu/drm/mediatek/mtk_dsi.c +++ b/drivers/gpu/drm/mediatek/mtk_dsi.c @@ -1002,12 +1002,6 @@ static int mtk_dsi_host_attach(struct mipi_dsi_host *host, return PTR_ERR(dsi->next_bridge); }
- /* - * set flag to request the DSI host bridge be pre-enabled before device bridge - * in the chain, so the DSI host is ready when the device bridge is pre-enabled - */ - dsi->next_bridge->pre_enable_prev_first = true; - drm_bridge_add(&dsi->bridge);
ret = component_add(host->dev, &mtk_dsi_component_ops);
TI's OLDI and DSI encoders need to be set up before the crtc is enabled, but the DRM helpers will enable the crtc first. This causes various issues on TI platforms, like visual artifacts or crtc sync lost warnings.
Thus drm_atomic_helper_commit_modeset_enables() and drm_atomic_helper_commit_modeset_disables() cannot be used, as they enable the crtc before bridges' pre-enable, and disable the crtc after bridges' post-disable.
Open code the drm_atomic_helper_commit_modeset_enables() and drm_atomic_helper_commit_modeset_disables(), and first call the bridges' pre-enables, then crtc enable, then bridges' post-enable (and vice versa for disable).
Signed-off-by: Tomi Valkeinen tomi.valkeinen@ideasonboard.com Cc: stable@vger.kernel.org # v6.17+ --- drivers/gpu/drm/tidss/tidss_kms.c | 30 +++++++++++++++++++++++++++--- 1 file changed, 27 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/tidss/tidss_kms.c b/drivers/gpu/drm/tidss/tidss_kms.c index 86eb5d97410b..8bb93194e5ac 100644 --- a/drivers/gpu/drm/tidss/tidss_kms.c +++ b/drivers/gpu/drm/tidss/tidss_kms.c @@ -26,9 +26,33 @@ static void tidss_atomic_commit_tail(struct drm_atomic_state *old_state)
tidss_runtime_get(tidss);
- drm_atomic_helper_commit_modeset_disables(ddev, old_state); - drm_atomic_helper_commit_planes(ddev, old_state, DRM_PLANE_COMMIT_ACTIVE_ONLY); - drm_atomic_helper_commit_modeset_enables(ddev, old_state); + /* + * TI's OLDI and DSI encoders need to be set up before the crtc is + * enabled. Thus drm_atomic_helper_commit_modeset_enables() and + * drm_atomic_helper_commit_modeset_disables() cannot be used here, as + * they enable the crtc before bridges' pre-enable, and disable the crtc + * after bridges' post-disable. + * + * Open code the functions here and first call the bridges' pre-enables, + * then crtc enable, then bridges' post-enable (and vice versa for + * disable). + */ + + drm_atomic_helper_commit_encoder_bridge_disable(ddev, old_state); + drm_atomic_helper_commit_crtc_disable(ddev, old_state); + drm_atomic_helper_commit_encoder_bridge_post_disable(ddev, old_state); + + drm_atomic_helper_update_legacy_modeset_state(ddev, old_state); + drm_atomic_helper_calc_timestamping_constants(old_state); + drm_atomic_helper_commit_crtc_set_mode(ddev, old_state); + + drm_atomic_helper_commit_planes(ddev, old_state, + DRM_PLANE_COMMIT_ACTIVE_ONLY); + + drm_atomic_helper_commit_encoder_bridge_pre_enable(ddev, old_state); + drm_atomic_helper_commit_crtc_enable(ddev, old_state); + drm_atomic_helper_commit_encoder_bridge_enable(ddev, old_state); + drm_atomic_helper_commit_writebacks(ddev, old_state);
drm_atomic_helper_commit_hw_done(old_state); drm_atomic_helper_wait_for_flip_done(ddev, old_state);
From: Linus Walleij linusw@kernel.org
Export and namespace those not prefixed with drm_* so it becomes possible to write custom commit tail functions in individual drivers using the helper infrastructure.
Tested-by: Marek Vasut marek.vasut+renesas@mailbox.org Reviewed-by: Maxime Ripard mripard@kernel.org Signed-off-by: Linus Walleij linusw@kernel.org [Tomi: Resolved conflicts, fixed indentation] Signed-off-by: Tomi Valkeinen tomi.valkeinen@ideasonboard.com Cc: stable@vger.kernel.org # v6.17+ --- drivers/gpu/drm/drm_atomic_helper.c | 122 +++++++++++++++++++++++++++++------- include/drm/drm_atomic_helper.h | 22 +++++++ 2 files changed, 121 insertions(+), 23 deletions(-)
diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c index ef97f37560b2..5beea645035f 100644 --- a/drivers/gpu/drm/drm_atomic_helper.c +++ b/drivers/gpu/drm/drm_atomic_helper.c @@ -1162,8 +1162,18 @@ crtc_needs_disable(struct drm_crtc_state *old_state, new_state->self_refresh_active; }
-static void -encoder_bridge_disable(struct drm_device *dev, struct drm_atomic_state *state) +/** + * drm_atomic_helper_commit_encoder_bridge_disable - disable bridges and encoder + * @dev: DRM device + * @state: the driver state object + * + * Loops over all connectors in the current state and if the CRTC needs + * it, disables the bridge chain all the way, then disables the encoder + * afterwards. + */ +void +drm_atomic_helper_commit_encoder_bridge_disable(struct drm_device *dev, + struct drm_atomic_state *state) { struct drm_connector *connector; struct drm_connector_state *old_conn_state, *new_conn_state; @@ -1229,9 +1239,18 @@ encoder_bridge_disable(struct drm_device *dev, struct drm_atomic_state *state) } } } +EXPORT_SYMBOL(drm_atomic_helper_commit_encoder_bridge_disable);
-static void -crtc_disable(struct drm_device *dev, struct drm_atomic_state *state) +/** + * drm_atomic_helper_commit_crtc_disable - disable CRTSs + * @dev: DRM device + * @state: the driver state object + * + * Loops over all CRTCs in the current state and if the CRTC needs + * it, disables it. + */ +void +drm_atomic_helper_commit_crtc_disable(struct drm_device *dev, struct drm_atomic_state *state) { struct drm_crtc *crtc; struct drm_crtc_state *old_crtc_state, *new_crtc_state; @@ -1282,9 +1301,18 @@ crtc_disable(struct drm_device *dev, struct drm_atomic_state *state) drm_crtc_vblank_put(crtc); } } +EXPORT_SYMBOL(drm_atomic_helper_commit_crtc_disable);
-static void -encoder_bridge_post_disable(struct drm_device *dev, struct drm_atomic_state *state) +/** + * drm_atomic_helper_commit_encoder_bridge_post_disable - post-disable encoder bridges + * @dev: DRM device + * @state: the driver state object + * + * Loops over all connectors in the current state and if the CRTC needs + * it, post-disables all encoder bridges. + */ +void +drm_atomic_helper_commit_encoder_bridge_post_disable(struct drm_device *dev, struct drm_atomic_state *state) { struct drm_connector *connector; struct drm_connector_state *old_conn_state, *new_conn_state; @@ -1335,15 +1363,16 @@ encoder_bridge_post_disable(struct drm_device *dev, struct drm_atomic_state *sta drm_bridge_put(bridge); } } +EXPORT_SYMBOL(drm_atomic_helper_commit_encoder_bridge_post_disable);
static void disable_outputs(struct drm_device *dev, struct drm_atomic_state *state) { - encoder_bridge_disable(dev, state); + drm_atomic_helper_commit_encoder_bridge_disable(dev, state);
- encoder_bridge_post_disable(dev, state); + drm_atomic_helper_commit_encoder_bridge_post_disable(dev, state);
- crtc_disable(dev, state); + drm_atomic_helper_commit_crtc_disable(dev, state); }
/** @@ -1446,8 +1475,17 @@ void drm_atomic_helper_calc_timestamping_constants(struct drm_atomic_state *stat } EXPORT_SYMBOL(drm_atomic_helper_calc_timestamping_constants);
-static void -crtc_set_mode(struct drm_device *dev, struct drm_atomic_state *state) +/** + * drm_atomic_helper_commit_crtc_set_mode - set the new mode + * @dev: DRM device + * @state: the driver state object + * + * Loops over all connectors in the current state and if the mode has + * changed, change the mode of the CRTC, then call down the bridge + * chain and change the mode in all bridges as well. + */ +void +drm_atomic_helper_commit_crtc_set_mode(struct drm_device *dev, struct drm_atomic_state *state) { struct drm_crtc *crtc; struct drm_crtc_state *new_crtc_state; @@ -1508,6 +1546,7 @@ crtc_set_mode(struct drm_device *dev, struct drm_atomic_state *state) drm_bridge_put(bridge); } } +EXPORT_SYMBOL(drm_atomic_helper_commit_crtc_set_mode);
/** * drm_atomic_helper_commit_modeset_disables - modeset commit to disable outputs @@ -1531,12 +1570,21 @@ void drm_atomic_helper_commit_modeset_disables(struct drm_device *dev, drm_atomic_helper_update_legacy_modeset_state(dev, state); drm_atomic_helper_calc_timestamping_constants(state);
- crtc_set_mode(dev, state); + drm_atomic_helper_commit_crtc_set_mode(dev, state); } EXPORT_SYMBOL(drm_atomic_helper_commit_modeset_disables);
-static void drm_atomic_helper_commit_writebacks(struct drm_device *dev, - struct drm_atomic_state *state) +/** + * drm_atomic_helper_commit_writebacks - issue writebacks + * @dev: DRM device + * @state: atomic state object being committed + * + * This loops over the connectors, checks if the new state requires + * a writeback job to be issued and in that case issues an atomic + * commit on each connector. + */ +void drm_atomic_helper_commit_writebacks(struct drm_device *dev, + struct drm_atomic_state *state) { struct drm_connector *connector; struct drm_connector_state *new_conn_state; @@ -1555,9 +1603,18 @@ static void drm_atomic_helper_commit_writebacks(struct drm_device *dev, } } } +EXPORT_SYMBOL(drm_atomic_helper_commit_writebacks);
-static void -encoder_bridge_pre_enable(struct drm_device *dev, struct drm_atomic_state *state) +/** + * drm_atomic_helper_commit_encoder_bridge_pre_enable - pre-enable bridges + * @dev: DRM device + * @state: atomic state object being committed + * + * This loops over the connectors and if the CRTC needs it, pre-enables + * the entire bridge chain. + */ +void +drm_atomic_helper_commit_encoder_bridge_pre_enable(struct drm_device *dev, struct drm_atomic_state *state) { struct drm_connector *connector; struct drm_connector_state *new_conn_state; @@ -1588,9 +1645,18 @@ encoder_bridge_pre_enable(struct drm_device *dev, struct drm_atomic_state *state drm_bridge_put(bridge); } } +EXPORT_SYMBOL(drm_atomic_helper_commit_encoder_bridge_pre_enable);
-static void -crtc_enable(struct drm_device *dev, struct drm_atomic_state *state) +/** + * drm_atomic_helper_commit_crtc_enable - enables the CRTCs + * @dev: DRM device + * @state: atomic state object being committed + * + * This loops over CRTCs in the new state, and of the CRTC needs + * it, enables it. + */ +void +drm_atomic_helper_commit_crtc_enable(struct drm_device *dev, struct drm_atomic_state *state) { struct drm_crtc *crtc; struct drm_crtc_state *old_crtc_state; @@ -1619,9 +1685,18 @@ crtc_enable(struct drm_device *dev, struct drm_atomic_state *state) } } } +EXPORT_SYMBOL(drm_atomic_helper_commit_crtc_enable);
-static void -encoder_bridge_enable(struct drm_device *dev, struct drm_atomic_state *state) +/** + * drm_atomic_helper_commit_encoder_bridge_enable - enables the bridges + * @dev: DRM device + * @state: atomic state object being committed + * + * This loops over all connectors in the new state, and of the CRTC needs + * it, enables the entire bridge chain. + */ +void +drm_atomic_helper_commit_encoder_bridge_enable(struct drm_device *dev, struct drm_atomic_state *state) { struct drm_connector *connector; struct drm_connector_state *new_conn_state; @@ -1664,6 +1739,7 @@ encoder_bridge_enable(struct drm_device *dev, struct drm_atomic_state *state) drm_bridge_put(bridge); } } +EXPORT_SYMBOL(drm_atomic_helper_commit_encoder_bridge_enable);
/** * drm_atomic_helper_commit_modeset_enables - modeset commit to enable outputs @@ -1682,11 +1758,11 @@ encoder_bridge_enable(struct drm_device *dev, struct drm_atomic_state *state) void drm_atomic_helper_commit_modeset_enables(struct drm_device *dev, struct drm_atomic_state *state) { - crtc_enable(dev, state); + drm_atomic_helper_commit_crtc_enable(dev, state);
- encoder_bridge_pre_enable(dev, state); + drm_atomic_helper_commit_encoder_bridge_pre_enable(dev, state);
- encoder_bridge_enable(dev, state); + drm_atomic_helper_commit_encoder_bridge_enable(dev, state);
drm_atomic_helper_commit_writebacks(dev, state); } diff --git a/include/drm/drm_atomic_helper.h b/include/drm/drm_atomic_helper.h index 53382fe93537..e154ee4f0696 100644 --- a/include/drm/drm_atomic_helper.h +++ b/include/drm/drm_atomic_helper.h @@ -60,6 +60,12 @@ int drm_atomic_helper_check_plane_state(struct drm_plane_state *plane_state, int drm_atomic_helper_check_planes(struct drm_device *dev, struct drm_atomic_state *state); int drm_atomic_helper_check_crtc_primary_plane(struct drm_crtc_state *crtc_state); +void drm_atomic_helper_commit_encoder_bridge_disable(struct drm_device *dev, + struct drm_atomic_state *state); +void drm_atomic_helper_commit_crtc_disable(struct drm_device *dev, + struct drm_atomic_state *state); +void drm_atomic_helper_commit_encoder_bridge_post_disable(struct drm_device *dev, + struct drm_atomic_state *state); int drm_atomic_helper_check(struct drm_device *dev, struct drm_atomic_state *state); void drm_atomic_helper_commit_tail(struct drm_atomic_state *state); @@ -89,8 +95,24 @@ drm_atomic_helper_update_legacy_modeset_state(struct drm_device *dev, void drm_atomic_helper_calc_timestamping_constants(struct drm_atomic_state *state);
+void drm_atomic_helper_commit_crtc_set_mode(struct drm_device *dev, + struct drm_atomic_state *state); + void drm_atomic_helper_commit_modeset_disables(struct drm_device *dev, struct drm_atomic_state *state); + +void drm_atomic_helper_commit_writebacks(struct drm_device *dev, + struct drm_atomic_state *state); + +void drm_atomic_helper_commit_encoder_bridge_pre_enable(struct drm_device *dev, + struct drm_atomic_state *state); + +void drm_atomic_helper_commit_crtc_enable(struct drm_device *dev, + struct drm_atomic_state *state); + +void drm_atomic_helper_commit_encoder_bridge_enable(struct drm_device *dev, + struct drm_atomic_state *state); + void drm_atomic_helper_commit_modeset_enables(struct drm_device *dev, struct drm_atomic_state *old_state);
On Fri, Dec 5, 2025 at 10:52 AM Tomi Valkeinen tomi.valkeinen@ideasonboard.com wrote:
Changing the enable/disable sequence in commit c9b1150a68d9 ("drm/atomic-helper: Re-order bridge chain pre-enable and post-disable") has caused regressions on multiple platforms: R-Car, MCDE, Rockchip.
This is an alternate series to Linus' series:
https://lore.kernel.org/all/20251202-mcde-drm-regression-thirdfix-v6-0-f1bff...
This series first reverts the original commit and reverts a fix for mediatek which is no longer needed. It then exposes helper functions from DRM core, and finally implements the new sequence only in the tidss driver.
There is one more fix in upstream for the original commit, commit 5d91394f2361 ("drm/exynos: fimd: Guard display clock control with runtime PM calls"), but I have not reverted that one as it looks like a valid patch in its own.
I added Cc stable v6.17+ to all patches, but I didn't add Fixes tags, as I wasn't sure what should they point to. But I could perhaps add Fixes: <original commit> to all of these.
Signed-off-by: Tomi Valkeinen tomi.valkeinen@ideasonboard.com
The series: Reviewed-by: Linus Walleij linusw@kernel.org Tested-by: Linus Walleij linusw@kernel.org
In my opinion Laurent is the more senior maintainer and my trust level in him is the highest of all the maintainers, so I think we should apply this revert series if Laurent ACKs that this is what he thinks is best for DRI.
Yours, Linus Walleij
On 05.12.2025 10:51, Tomi Valkeinen wrote:
Changing the enable/disable sequence in commit c9b1150a68d9 ("drm/atomic-helper: Re-order bridge chain pre-enable and post-disable") has caused regressions on multiple platforms: R-Car, MCDE, Rockchip.
This is an alternate series to Linus' series:
https://lore.kernel.org/all/20251202-mcde-drm-regression-thirdfix-v6-0-f1bff...
This series first reverts the original commit and reverts a fix for mediatek which is no longer needed. It then exposes helper functions from DRM core, and finally implements the new sequence only in the tidss driver.
There is one more fix in upstream for the original commit, commit 5d91394f2361 ("drm/exynos: fimd: Guard display clock control with runtime PM calls"), but I have not reverted that one as it looks like a valid patch in its own.
Right, that patch is a fix on its own, the changes in the atomic sequence just revealed the issue.
I added Cc stable v6.17+ to all patches, but I didn't add Fixes tags, as I wasn't sure what should they point to. But I could perhaps add Fixes: <original commit> to all of these.
Signed-off-by: Tomi Valkeinen tomi.valkeinen@ideasonboard.com
Linus Walleij (1): drm/atomic-helper: Export and namespace some functions
Tomi Valkeinen (3): Revert "drm/atomic-helper: Re-order bridge chain pre-enable and post-disable" Revert "drm/mediatek: dsi: Fix DSI host and panel bridge pre-enable order" drm/tidss: Fix enable/disable order
drivers/gpu/drm/drm_atomic_helper.c | 122 ++++++++++++++---- drivers/gpu/drm/mediatek/mtk_dsi.c | 6 - drivers/gpu/drm/tidss/tidss_kms.c | 30 ++++- include/drm/drm_atomic_helper.h | 22 ++++ include/drm/drm_bridge.h | 249 ++++++++++-------------------------- 5 files changed, 214 insertions(+), 215 deletions(-)
base-commit: 88e721ab978a86426aa08da520de77430fa7bb84 change-id: 20251205-drm-seq-fix-b4ed1f56604b
Best regards
On Fri, 5 Dec 2025 11:51:47 +0200, Tomi Valkeinen wrote:
Changing the enable/disable sequence in commit c9b1150a68d9 ("drm/atomic-helper: Re-order bridge chain pre-enable and post-disable") has caused regressions on multiple platforms: R-Car, MCDE, Rockchip.
This is an alternate series to Linus' series:
[ ... ]
Reviewed-by: Maxime Ripard mripard@kernel.org
Thanks! Maxime
Hi Tomi,
Thank you for posting this series.
It makes sense to change the order in tidss _commit_tail(), than to undo the order changes in the regressed drivers.
On 05/12/2025 09:51, Tomi Valkeinen wrote:
This reverts commit c9b1150a68d9362a0827609fc0dc1664c0d8bfe1.
Changing the enable/disable sequence has caused regressions on multiple platforms: R-Car, MCDE, Rockchip. A series (see link below) was sent to fix these, but it was decided that it's better to revert the original patch and change the enable/disable sequence only in the tidss driver.
Reverting this commit breaks tidss's DSI and OLDI outputs, which will be fixed in the following commits.
Signed-off-by: Tomi Valkeinen tomi.valkeinen@ideasonboard.com Link: https://lore.kernel.org/all/20251202-mcde-drm-regression-thirdfix-v6-0-f1bff... Fixes: c9b1150a68d9 ("drm/atomic-helper: Re-order bridge chain pre-enable and post-disable") Cc: stable@vger.kernel.org # v6.17+
drivers/gpu/drm/drm_atomic_helper.c | 8 +- include/drm/drm_bridge.h | 249 ++++++++++-------------------------- 2 files changed, 70 insertions(+), 187 deletions(-)
Reviewed-by: Aradhya Bhatia aradhya.bhatia@linux.dev
On 05/12/2025 09:51, Tomi Valkeinen wrote:
From: Linus Walleij linusw@kernel.org
Export and namespace those not prefixed with drm_* so it becomes possible to write custom commit tail functions in individual drivers using the helper infrastructure.
Tested-by: Marek Vasut marek.vasut+renesas@mailbox.org Reviewed-by: Maxime Ripard mripard@kernel.org Signed-off-by: Linus Walleij linusw@kernel.org [Tomi: Resolved conflicts, fixed indentation] Signed-off-by: Tomi Valkeinen tomi.valkeinen@ideasonboard.com Cc: stable@vger.kernel.org # v6.17+
drivers/gpu/drm/drm_atomic_helper.c | 122 +++++++++++++++++++++++++++++------- include/drm/drm_atomic_helper.h | 22 +++++++ 2 files changed, 121 insertions(+), 23 deletions(-)
Reviewed-by: Aradhya Bhatia aradhya.bhatia@linux.dev
On 05/12/2025 09:51, Tomi Valkeinen wrote:
TI's OLDI and DSI encoders need to be set up before the crtc is enabled, but the DRM helpers will enable the crtc first. This causes various issues on TI platforms, like visual artifacts or crtc sync lost warnings.
Thus drm_atomic_helper_commit_modeset_enables() and drm_atomic_helper_commit_modeset_disables() cannot be used, as they enable the crtc before bridges' pre-enable, and disable the crtc after bridges' post-disable.
Open code the drm_atomic_helper_commit_modeset_enables() and drm_atomic_helper_commit_modeset_disables(), and first call the bridges' pre-enables, then crtc enable, then bridges' post-enable (and vice versa for disable).
Signed-off-by: Tomi Valkeinen tomi.valkeinen@ideasonboard.com Cc: stable@vger.kernel.org # v6.17+
drivers/gpu/drm/tidss/tidss_kms.c | 30 +++++++++++++++++++++++++++--- 1 file changed, 27 insertions(+), 3 deletions(-)
Reviewed-by: Aradhya Bhatia aradhya.bhatia@linux.dev
Hi,
On 05/12/2025 11:51, Tomi Valkeinen wrote:
Changing the enable/disable sequence in commit c9b1150a68d9 ("drm/atomic-helper: Re-order bridge chain pre-enable and post-disable") has caused regressions on multiple platforms: R-Car, MCDE, Rockchip.
This is an alternate series to Linus' series:
https://lore.kernel.org/all/20251202-mcde-drm-regression-thirdfix-v6-0-f1bff...
This series first reverts the original commit and reverts a fix for mediatek which is no longer needed. It then exposes helper functions from DRM core, and finally implements the new sequence only in the tidss driver.
There is one more fix in upstream for the original commit, commit 5d91394f2361 ("drm/exynos: fimd: Guard display clock control with runtime PM calls"), but I have not reverted that one as it looks like a valid patch in its own.
I added Cc stable v6.17+ to all patches, but I didn't add Fixes tags, as I wasn't sure what should they point to. But I could perhaps add Fixes: <original commit> to all of these.
There has been no comments, so I assume this is the way to go.
Should we merge this series as a fix for 6.18 rcs?
Tomi
On Fri, Dec 12, 2025 at 3:21 PM Tomi Valkeinen tomi.valkeinen@ideasonboard.com wrote:
On 05/12/2025 11:51, Tomi Valkeinen wrote:
Changing the enable/disable sequence in commit c9b1150a68d9 ("drm/atomic-helper: Re-order bridge chain pre-enable and post-disable") has caused regressions on multiple platforms: R-Car, MCDE, Rockchip.
This is an alternate series to Linus' series:
https://lore.kernel.org/all/20251202-mcde-drm-regression-thirdfix-v6-0-f1bff...
This series first reverts the original commit and reverts a fix for mediatek which is no longer needed. It then exposes helper functions from DRM core, and finally implements the new sequence only in the tidss driver.
There is one more fix in upstream for the original commit, commit 5d91394f2361 ("drm/exynos: fimd: Guard display clock control with runtime PM calls"), but I have not reverted that one as it looks like a valid patch in its own.
I added Cc stable v6.17+ to all patches, but I didn't add Fixes tags, as I wasn't sure what should they point to. But I could perhaps add Fixes: <original commit> to all of these.
There has been no comments, so I assume this is the way to go.
Should we merge this series as a fix for 6.18 rcs?
Too late now, so let's merge it as a fix for v6.19 rcs!
Yours, Linus Walleij
Hi,
On 14/12/2025 13:14, Linus Walleij wrote:
On Fri, Dec 12, 2025 at 3:21 PM Tomi Valkeinen tomi.valkeinen@ideasonboard.com wrote:
On 05/12/2025 11:51, Tomi Valkeinen wrote:
Changing the enable/disable sequence in commit c9b1150a68d9 ("drm/atomic-helper: Re-order bridge chain pre-enable and post-disable") has caused regressions on multiple platforms: R-Car, MCDE, Rockchip.
This is an alternate series to Linus' series:
https://lore.kernel.org/all/20251202-mcde-drm-regression-thirdfix-v6-0-f1bff...
This series first reverts the original commit and reverts a fix for mediatek which is no longer needed. It then exposes helper functions from DRM core, and finally implements the new sequence only in the tidss driver.
There is one more fix in upstream for the original commit, commit 5d91394f2361 ("drm/exynos: fimd: Guard display clock control with runtime PM calls"), but I have not reverted that one as it looks like a valid patch in its own.
I added Cc stable v6.17+ to all patches, but I didn't add Fixes tags, as I wasn't sure what should they point to. But I could perhaps add Fixes: <original commit> to all of these.
There has been no comments, so I assume this is the way to go.
Should we merge this series as a fix for 6.18 rcs?
Too late now, so let's merge it as a fix for v6.19 rcs!
Ah, right. Indeed, I meant v6.19 rcs.
Tomi
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