From: Brian Norris briannorris@chromium.org
commit 2bdba9d4a3baa758c2ca7f5b37b35c7b3391dc42 upstream.
If we disable vblank when entering self-refresh, vblank APIs (like DRM_IOCTL_WAIT_VBLANK) no longer work. But user space is not aware when we enter self-refresh, so this appears to be an API violation -- that DRM_IOCTL_WAIT_VBLANK fails with EINVAL whenever the display is idle and enters self-refresh.
The downstream driver used by many of these systems never used to disable vblank for PSR, and in fact, even upstream, we didn't do that until radically redesigning the state machine in commit 6c836d965bad ("drm/rockchip: Use the helpers for PSR").
Thus, it seems like a reasonable API fix to simply restore that behavior, and leave vblank enabled.
Note that this appears to potentially unbalance the drm_crtc_vblank_{off,on}() calls in some cases, but: (a) drm_crtc_vblank_on() documents this as OK and (b) if I do the naive balancing, I find state machine issues such that we're not in sync properly; so it's easier to take advantage of (a).
This issue was exposed by IGT's kms_vblank tests, and reported by KernelCI. The bug has been around a while (longer than KernelCI noticed), but was only exposed once self-refresh was bugfixed more recently, and so KernelCI could properly test it. Some other notes in:
https://lore.kernel.org/dri-devel/Y6OCg9BPnJvimQLT@google.com/ Re: renesas/master bisection: igt-kms-rockchip.kms_vblank.pipe-A-wait-forked on rk3399-gru-kevin
== Backporting notes: ==
Marking as 'Fixes' commit 6c836d965bad ("drm/rockchip: Use the helpers for PSR"), but it probably depends on commit bed030a49f3e ("drm/rockchip: Don't fully disable vop on self refresh") as well.
We also need the previous patch ("drm/atomic: Allow vblank-enabled + self-refresh "disable""), of course.
v3: * no update
v2: * skip unnecessary lock/unlock
Fixes: 6c836d965bad ("drm/rockchip: Use the helpers for PSR") Cc: stable@vger.kernel.org Reported-by: "kernelci.org bot" bot@kernelci.org Link: https://lore.kernel.org/dri-devel/Y5itf0+yNIQa6fU4@sirena.org.uk/ Signed-off-by: Brian Norris briannorris@chromium.org Signed-off-by: Sean Paul seanpaul@chromium.org Link: https://patchwork.freedesktop.org/patch/msgid/20230109171809.v3.2.Ic07cba4ab... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/gpu/drm/rockchip/rockchip_drm_vop.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
--- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c @@ -717,13 +717,13 @@ static void vop_crtc_atomic_disable(stru if (crtc->state->self_refresh_active) rockchip_drm_set_win_enabled(crtc, false);
+ if (crtc->state->self_refresh_active) + goto out; + mutex_lock(&vop->vop_lock);
drm_crtc_vblank_off(crtc);
- if (crtc->state->self_refresh_active) - goto out; - /* * Vop standby will take effect at end of current frame, * if dsp hold valid irq happen, it means standby complete. @@ -757,9 +757,9 @@ static void vop_crtc_atomic_disable(stru vop_core_clks_disable(vop); pm_runtime_put(vop->dev);
-out: mutex_unlock(&vop->vop_lock);
+out: if (crtc->state->event && !crtc->state->active) { spin_lock_irq(&crtc->dev->event_lock); drm_crtc_send_vblank_event(crtc, crtc->state->event);