It's possible to change which CRTC is in use for a given connector/encoder/bridge while we're in self-refresh without fully disabling the connector/encoder/bridge along the way. This can confuse the bridge encoder/bridge, because (a) it needs to track the SR state (trying to perform "active" operations while the panel is still in SR can be Bad(TM)); and (b) it tracks the SR state via the CRTC state (and after the switch, the previous SR state is lost).
Thus, we need to either somehow carry the self-refresh state over to the new CRTC, or else force an encoder/bridge self-refresh transition during such a switch.
I choose the latter, so we disable the encoder (and exit PSR) before attaching it to the new CRTC (where we can continue to assume a clean (non-self-refresh) state).
This fixes PSR issues seen on Rockchip RK3399 systems with drivers/gpu/drm/bridge/analogix/analogix_dp_core.c.
Change in v2:
- Drop "->enable" condition; this could possibly be "->active" to reflect the intended hardware state, but it also is a little over-specific. We want to make a transition through "disabled" any time we're exiting PSR at the same time as a CRTC switch. (Thanks Liu Ying)
Cc: Liu Ying victor.liu@oss.nxp.com Cc: stable@vger.kernel.org Fixes: 1452c25b0e60 ("drm: Add helpers to kick off self refresh mode in drivers") Signed-off-by: Brian Norris briannorris@chromium.org --- drivers/gpu/drm/drm_atomic_helper.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c index 9603193d2fa1..987e4b212e9f 100644 --- a/drivers/gpu/drm/drm_atomic_helper.c +++ b/drivers/gpu/drm/drm_atomic_helper.c @@ -1011,9 +1011,19 @@ crtc_needs_disable(struct drm_crtc_state *old_state, return drm_atomic_crtc_effectively_active(old_state);
/* - * We need to run through the crtc_funcs->disable() function if the CRTC - * is currently on, if it's transitioning to self refresh mode, or if - * it's in self refresh mode and needs to be fully disabled. + * We need to disable bridge(s) and CRTC if we're transitioning out of + * self-refresh and changing CRTCs at the same time, because the + * bridge tracks self-refresh status via CRTC state. + */ + if (old_state->self_refresh_active && + old_state->crtc != new_state->crtc) + return true; + + /* + * We also need to run through the crtc_funcs->disable() function if + * the CRTC is currently on, if it's transitioning to self refresh + * mode, or if it's in self refresh mode and needs to be fully + * disabled. */ return old_state->active || (old_state->self_refresh_active && !new_state->active) ||
On Mon, 2022-02-28 at 12:25 -0800, Brian Norris wrote:
It's possible to change which CRTC is in use for a given connector/encoder/bridge while we're in self-refresh without fully disabling the connector/encoder/bridge along the way. This can confuse the bridge encoder/bridge, because (a) it needs to track the SR state (trying to perform "active" operations while the panel is still in SR can be Bad(TM)); and (b) it tracks the SR state via the CRTC state (and after the switch, the previous SR state is lost).
Thus, we need to either somehow carry the self-refresh state over to the new CRTC, or else force an encoder/bridge self-refresh transition during such a switch.
I choose the latter, so we disable the encoder (and exit PSR) before attaching it to the new CRTC (where we can continue to assume a clean (non-self-refresh) state).
This fixes PSR issues seen on Rockchip RK3399 systems with drivers/gpu/drm/bridge/analogix/analogix_dp_core.c.
Change in v2:
- Drop "->enable" condition; this could possibly be "->active" to reflect the intended hardware state, but it also is a little over-specific. We want to make a transition through "disabled" any time we're exiting PSR at the same time as a CRTC switch.
Cool. I don't see any particular issue regarding the drop.
Liu Ying
(Thanks Liu Ying)
Cc: Liu Ying victor.liu@oss.nxp.com Cc: stable@vger.kernel.org Fixes: 1452c25b0e60 ("drm: Add helpers to kick off self refresh mode in drivers") Signed-off-by: Brian Norris briannorris@chromium.org
drivers/gpu/drm/drm_atomic_helper.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c index 9603193d2fa1..987e4b212e9f 100644 --- a/drivers/gpu/drm/drm_atomic_helper.c +++ b/drivers/gpu/drm/drm_atomic_helper.c @@ -1011,9 +1011,19 @@ crtc_needs_disable(struct drm_crtc_state *old_state, return drm_atomic_crtc_effectively_active(old_state); /*
* We need to run through the crtc_funcs->disable() function if the CRTC* is currently on, if it's transitioning to self refresh mode, or if* it's in self refresh mode and needs to be fully disabled.
* We need to disable bridge(s) and CRTC if we're transitioning out of* self-refresh and changing CRTCs at the same time, because the* bridge tracks self-refresh status via CRTC state.*/- if (old_state->self_refresh_active &&
old_state->crtc != new_state->crtc)return true;- /*
* We also need to run through the crtc_funcs->disable() function if* the CRTC is currently on, if it's transitioning to self refresh* mode, or if it's in self refresh mode and needs to be fully* disabled.
linux-stable-mirror@lists.linaro.org
-
Brian Norris -
Liu Ying