Re: [PATCH] drm/msm/dpu: Delete bonkers code

From: Stephen Boyd
Date: Fri Apr 30 2021 - 13:44:57 EST


Quoting Rob Clark (2021-04-30 10:17:39)
> From: Rob Clark <robdclark@xxxxxxxxxxxx>
>
> dpu_crtc_atomic_flush() was directly poking it's attached planes in a
> code path that ended up in dpu_plane_atomic_update(), even if the plane
> was not involved in the current atomic update. While a bit dubious,
> this worked before because plane->state would always point to something
> valid. But now using drm_atomic_get_new_plane_state() we could get a
> NULL state pointer instead, leading to:
>
> [ 20.873273] Call trace:
> [ 20.875740] dpu_plane_atomic_update+0x5c/0xed0
> [ 20.880311] dpu_plane_restore+0x40/0x88
> [ 20.884266] dpu_crtc_atomic_flush+0xf4/0x208
> [ 20.888660] drm_atomic_helper_commit_planes+0x150/0x238
> [ 20.894014] msm_atomic_commit_tail+0x1d4/0x7a0
> [ 20.898579] commit_tail+0xa4/0x168
> [ 20.902102] drm_atomic_helper_commit+0x164/0x178
> [ 20.906841] drm_atomic_commit+0x54/0x60
> [ 20.910798] drm_atomic_connector_commit_dpms+0x10c/0x118
> [ 20.916236] drm_mode_obj_set_property_ioctl+0x1e4/0x440
> [ 20.921588] drm_connector_property_set_ioctl+0x60/0x88
> [ 20.926852] drm_ioctl_kernel+0xd0/0x120
> [ 20.930807] drm_ioctl+0x21c/0x478
> [ 20.934235] __arm64_sys_ioctl+0xa8/0xe0
> [ 20.938193] invoke_syscall+0x64/0x130
> [ 20.941977] el0_svc_common.constprop.3+0x5c/0xe0
> [ 20.946716] do_el0_svc+0x80/0xa0
> [ 20.950058] el0_svc+0x20/0x30
> [ 20.953145] el0_sync_handler+0x88/0xb0
> [ 20.957014] el0_sync+0x13c/0x140
>
> The reason for the codepath seems dubious, the atomic suspend/resume
> heplers should handle the power-collapse case. If not, the CRTC's
> atomic_check() should be adding the planes to the atomic update.
>
> Reported-by: Stephen Boyd <sboyd@xxxxxxxxxx>

Maybe better to use swboyd@xxxxxxxxxxxx for this one.

> Reported-by: John Stultz <john.stultz@xxxxxxxxxx>
> Fixes: 37418bf14c13 drm: Use state helper instead of the plane state pointer

Should be

Fixes: 37418bf14c13 ("drm: Use state helper instead of the plane state pointer")

to match the preferred format.

> Signed-off-by: Rob Clark <robdclark@xxxxxxxxxxxx>

Otherwise looks good, thanks.