[PATCH RESEND v2 1/3] drm/encoder: register per-encoder debugfs dir

[Maxime Ripard]

Hi Mark,

On Tue, Dec 05, 2023 at 04:13:41PM +0000, Mark Brown wrote:
> On Sun, Dec 03, 2023 at 02:53:13PM +0300, Dmitry Baryshkov wrote:
> 
> > Each of connectors and CRTCs used by the DRM device provides debugfs
> > directory, which is used by several standard debugfs files and can
> > further be extended by the driver. Add such generic debugfs directories
> > for encoder.
> 
> Today's -next fails to boot an imx_v6_v7_defconfig on at least the UDOO
> dual and quad platforms, based on i.MX6DL and i.MX6Q respectively.
> multi_v7_defconfig looks fine on the same boards, it's just the i.MX
> specific config that's failing.  Nothing else in my CI appears impacted.
> We get a NULL pointer defererence while bringing up the display
> subsystem:
> 
> [    1.392715] imx-drm display-subsystem: bound imx-ipuv3-crtc.7 (ops 0xc0f9a490)
> [    1.400013] imx-drm display-subsystem: bound 120000.hdmi (ops 0xc0f9af80)
> [    1.407193] 8<--- cut here ---
> [    1.410256] Unable to handle kernel NULL pointer dereference at virtual address 00000010 when read
> 
> ...
> 
> [    1.891882]  drm_debugfs_encoder_add from drm_encoder_register_all+0x20/0x60
> [    1.898954]  drm_encoder_register_all from drm_modeset_register_all+0x34/0x70
> [    1.906116]  drm_modeset_register_all from drm_dev_register+0x140/0x288
> [    1.912765]  drm_dev_register from imx_drm_bind+0xd0/0x128
> [    1.918284]  imx_drm_bind from try_to_bring_up_aggregate_device+0x164/0x1c4
> [    1.925275]  try_to_bring_up_aggregate_device from __component_add+0x90/0x13c
> 
> Full log at:
> 
>    https://lava.sirena.org.uk/scheduler/job/308781
> 
> A bisect identfied this patch (in -next as caf525ed45b4960b4) as being
> the commit that introduced the issue, bisect log below.  I've not done
> any other investigation but the commit does seem plausibly related to
> the backtrace in the oops.

I think it's the same issue than the one fixed by:
https://lore.kernel.org/all/20231205130631.3456986-1-m.szyprowski@samsung.com/

Maxime
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