Re: [PATCH v2 1/2] drm/i915/mso: using joiner is not possible with eDP MSO

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Fri, Jun 14, 2024 at 01:16:03PM +0300, Jani Nikula wrote:
> It's not possible to use the joiner at the same time with eDP MSO. When
> a panel needs MSO, it's not optional, so MSO trumps joiner.
> 
> While just reporting false for intel_dp_has_joiner() should be
> sufficient, also skip creation of the joiner force enable debugfs to
> better handle this in testing.
> 
> Cc: stable@vger.kernel.org
> Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
> Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/1668
> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_display_debugfs.c | 8 ++++++--
>  drivers/gpu/drm/i915/display/intel_dp.c              | 4 ++++
>  2 files changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_display_debugfs.c b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> index 91757fed9c6d..5eb31404436c 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> +++ b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> @@ -1546,8 +1546,12 @@ void intel_connector_debugfs_add(struct intel_connector *connector)
>  	if (DISPLAY_VER(i915) >= 11 &&
>  	    (connector_type == DRM_MODE_CONNECTOR_DisplayPort ||
>  	     connector_type == DRM_MODE_CONNECTOR_eDP)) {
> -		debugfs_create_bool("i915_bigjoiner_force_enable", 0644, root,
> -				    &connector->force_bigjoiner_enable);
> +		struct intel_dp *intel_dp = intel_attached_dp(connector);

That won't give you anything on MST. Dunno if there's any point in
trying to do anything here anyway. We don't account for the other
intel_dp_has_joiner() restrictions here either.

> +
> +		/* eDP MSO is not compatible with joiner */
> +		if (!intel_dp->mso_link_count)
> +			debugfs_create_bool("i915_bigjoiner_force_enable", 0644, root,
> +					    &connector->force_bigjoiner_enable);
>  	}
>  
>  	if (connector_type == DRM_MODE_CONNECTOR_DSI ||
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index 9a9bb0f5b7fe..ab33c9de393a 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -465,6 +465,10 @@ bool intel_dp_has_joiner(struct intel_dp *intel_dp)
>  	struct intel_encoder *encoder = &intel_dig_port->base;
>  	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
>  
> +	/* eDP MSO is not compatible with joiner */
> +	if (intel_dp->mso_link_count)
> +		return false;
> +

This part looks fine.

>  	return DISPLAY_VER(dev_priv) >= 12 ||
>  		(DISPLAY_VER(dev_priv) == 11 &&
>  		 encoder->port != PORT_A);
> -- 
> 2.39.2

-- 
Ville Syrjälä
Intel