[PATCH 1/2] drm/i915: Prevent HW access during init from SDVO TV get_modes hook

[Hogander, Jouni]

On Tue, 2024-02-06 at 17:39 +0200, Imre Deak wrote:
> Prevent accessing the HW from the SDVO/TV get_modes connector hook.
> Returning 0 from the hook will make the caller -
> drm_helper_probe_single_connector_modes() - keep the previously
> detected
> mode list of the connector.

I don't see where this is done? Not sure if looking at wrong place, but
I see it tries using some override edid and in case that fails as well
uses drm_add_modes_noedid?

> 
> Signed-off-by: Imre Deak <imre.deak at intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_sdvo.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_sdvo.c
> b/drivers/gpu/drm/i915/display/intel_sdvo.c
> index 2571ef5a1b211..ccea0efbd136f 100644
> --- a/drivers/gpu/drm/i915/display/intel_sdvo.c
> +++ b/drivers/gpu/drm/i915/display/intel_sdvo.c
> @@ -2287,6 +2287,7 @@ static const struct drm_display_mode
> sdvo_tv_modes[] = {
>  static int intel_sdvo_get_tv_modes(struct drm_connector *connector)

I see intel_sdvo_get_tv_modes is called from intel_sdvo_get_modes. Why
there is no need to do the same in intel_sdvo_get_lvds_modes and
intel_sdvo_get_ddc_modes as well?

BR,

Jouni Högander

>  {
>         struct intel_sdvo *intel_sdvo =
> intel_attached_sdvo(to_intel_connector(connector));
> +       struct drm_i915_private *i915 = to_i915(intel_sdvo-
> >base.base.dev);
>         struct intel_sdvo_connector *intel_sdvo_connector =
>                 to_intel_sdvo_connector(connector);
>         const struct drm_connector_state *conn_state = connector-
> >state;
> @@ -2298,6 +2299,9 @@ static int intel_sdvo_get_tv_modes(struct
> drm_connector *connector)
>         DRM_DEBUG_KMS("[CONNECTOR:%d:%s]\n",
>                       connector->base.id, connector->name);
>  
> +       if (!intel_display_driver_check_access(i915))
> +               return 0;
> +
>         /*
>          * Read the list of supported input resolutions for the
> selected TV
>          * format.