Re: [PATCH v5 1/2] drm/bridge: ti-sn65dsi83: Fix error handling in sn65dsi83_reset_work()

[Luca Ceresoli]

Hi Esben,

On Mon Aug 31, 2026 at 2:21 PM CEST, Esben Haabendal wrote:
> The error handling of sn65dsi83_reset_pipe() in sn65dsi83_reset_work() has
> seen a couple of changes that seems to cause a bit of confusion.
>
> While sn65dsi83_reset_work() has implemented an early exit if
> sn65dsi83_reset_pipe() fails since it was added, when a commit from Maxime
> Ripard switched to use drm_bridge_helper_reset_crtc() [1] the
> sn65dsi83_reset_pipe() function would no longer return an error code, so
> the early exit was then a no-op, and even on sn65dsi83_reset_pipe()
> failure, enable_irq() has been called.
>
> When drm_bridge_enter()/drm_bridge_exit() resource protection was added,
> the drm_bridge_exit() incidentally was always called, which is the correct
> approach. But only because the early exit in sn65dsi83_reset_pipe() was
> never hit because sn65dsi83_reset_pipe() always returns 0.
>
> In order get back to a situation where enable_irq() is not called on
> sn65dsi83_reset_pipe() failure, which should help protect against irq
> storms, we need to reintroduce a non-zero return value from
> sn65dsi83_reset_pipe() on error, and fix sn65dsi83_reset_work() so that we
> always exit the DRM bridge critical section with drm_bridge_exit().
>
> [1] commit e17fadff7ab9 ("drm/bridge: ti-sn65dsi83: Switch to drm_bridge_helper_reset_crtc")
> [2] commit d2e8d1bc840b ("drm/bridge: ti-sn65dsi83: protect device resources on unplug")
>
> Fixes: e17fadff7ab9 ("drm/bridge: ti-sn65dsi83: Switch to drm_bridge_helper_reset_crtc")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Esben Haabendal <esben@xxxxxxxxxx>

Thanks for having sorted out this complicated situation!

Now all patches are approved, so I'll apply them next week if all goes
well. Being one fix and one feature thay'll have to go to different
branches: drm-misc-fixes and drm-misc-next respectively. As I see it, the
two patches are orthogonal, so that shouldn't be a problem.

Luca

--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com