Re: [PATCH REGRESSION] drm/panel: simple: restore connector_type fallback

[Dmitry Baryshkov]

On Fri, Nov 21, 2025 at 02:20:48PM +0100, Ludovic Desroches wrote:
> The switch from devm_kzalloc() + drm_panel_init() to
> devm_drm_panel_alloc() introduced a regression.
> 
> Several panel descriptors do not set connector_type. For those panels,
> panel_simple_probe() used to compute a connector type (currently DPI as a
> fallback) and pass that value to drm_panel_init(). After the conversion
> to devm_drm_panel_alloc(), the call unconditionally used
> desc->connector_type instead, ignoring the computed fallback and
> potentially passing DRM_MODE_CONNECTOR_Unknown, which
> drm_panel_bridge_add() does not allow.
> 
> Move the connector_type validation / fallback logic before the
> devm_drm_panel_alloc() call and pass the computed connector_type to
> devm_drm_panel_alloc(), so panels without an explicit connector_type
> once again get the DPI default.
> 
> Signed-off-by: Ludovic Desroches <ludovic.desroches@xxxxxxxxxxxxx>
> Fixes: de04bb0089a9 ("drm/panel/panel-simple: Use the new allocation in place of devm_kzalloc()")
> ---
> Hi,
> 
> I am not sure whether this regression has already been reported or
> addressed. If it has, please feel free to drop this patch.

Would it be better to fix those panels instead? In the end, the panel
usually has only one bus.

> ---
>  drivers/gpu/drm/panel/panel-simple.c | 86 ++++++++++++++++++------------------
>  1 file changed, 43 insertions(+), 43 deletions(-)

-- 
With best wishes
Dmitry