Re: [PATCH RFC v2 16/24] drm/mipi-dsi: notify about DSI attach

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] drm: commit message contradicts ATTACHED event semantics
--

commit 3106f1037d08f7d82066d0ccd2f170f5facd1bf0
Author: Luca Ceresoli <luca.ceresoli@bootlin.com>

drm/mipi-dsi: notify about DSI attach

This commit introduces an event notification when a DSI device is attached to
its host. This is added in preparation for DRM bridge hotplug support.

>     In preparation to support DRM bridge hotplug, let the drm_mipi_dsi code
>     emit an event when a DSI device is attached to the corresponding DSI host,
>     so that this event can trigger the actions needed to deconfigure the
>     pipeline and unregister the connector as appropriate.

[Severity: Medium]
Does this commit message contradict the ATTACHED event semantics used in
mipi_dsi_attach() in drivers/gpu/drm/drm_mipi_dsi.c?

The commit message explicitly claims the DRM_MIPI_DSI_ATTACHED event is
intended to trigger actions to "deconfigure the pipeline and unregister the
connector". However, since this event is emitted when a device is attached,
shouldn't it be used to configure the pipeline and register the connector
(which is what the hotplug helper actually does)?

The teardown path is structurally safe because error unwinding (via devres)
calls drm_bridge_remove(), which detaches the bridge from the encoder and
emits DRM_BRIDGE_DETACHED. The hotplug helper correctly listens to
DRM_BRIDGE_DETACHED to unregister the connector, meaning the lifecycle is
perfectly symmetrical without needing a dedicated DRM_MIPI_DSI_DETACHED
event.

Could the commit message be updated to reflect that this event triggers
configuration and registration rather than deconfiguration and
unregistration?

> diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c
> index 3ac1dd5ad640a..eaa474da4a519 100644
> --- a/drivers/gpu/drm/drm_mipi_dsi.c
> +++ b/drivers/gpu/drm/drm_mipi_dsi.c
[ ... ]
> @@ -386,6 +387,8 @@ int mipi_dsi_attach(struct mipi_dsi_device *dsi)
>  
>  	dsi->attached = true;
>  
> +	drm_event_notifier_notify(DRM_MIPI_DSI_ATTACHED, dsi);
> +
>  	return 0;
>  }

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261001-drm-bridge-hotplug-v2-0-8e34986dcb68@bootlin.com?part=16