Re: [Intel-gfx] [PATCH 1/3] drm/i915: Reject bigjoiner if the pipe doesn't support it

[Jani Nikula <jani.nikula@linux.intel.com>]

On Fri, 21 Jan 2022, Ville Syrjala <ville.syrjala@linux.intel.com> wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
> Check that our crtc can in fact be the bigjoiner master before
> we let the modeset proceed with bigjoiner enabled.
>
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_display.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> index 0964b2403e2d..36e547bd0cbe 100644
> --- a/drivers/gpu/drm/i915/display/intel_display.c
> +++ b/drivers/gpu/drm/i915/display/intel_display.c
> @@ -4102,6 +4102,14 @@ static u8 bigjoiner_pipes(struct drm_i915_private *i915)
>  		return 0;
>  }
>  
> +static u8 bigjoiner_master_pipes(struct drm_i915_private *i915)
> +{
> +	u8 pipes = bigjoiner_pipes(i915);
> +
> +	/* last pipe can not be master */
> +	return pipes & (pipes >> 1);
> +}
> +
>  static bool transcoder_ddi_func_is_enabled(struct drm_i915_private *dev_priv,
>  					   enum transcoder cpu_transcoder)
>  {
> @@ -7600,6 +7608,7 @@ static int intel_atomic_check_bigjoiner(struct intel_atomic_state *state,
>  					struct intel_crtc_state *old_crtc_state,
>  					struct intel_crtc_state *new_crtc_state)
>  {
> +	struct drm_i915_private *i915 = to_i915(state->base.dev);
>  	struct intel_crtc_state *slave_crtc_state, *master_crtc_state;
>  	struct intel_crtc *slave_crtc, *master_crtc;
>  
> @@ -7615,6 +7624,13 @@ static int intel_atomic_check_bigjoiner(struct intel_atomic_state *state,
>  	if (!new_crtc_state->bigjoiner)
>  		return 0;
>  
> +	if ((bigjoiner_master_pipes(i915) & BIT(crtc->pipe)) == 0) {

Feels like the check should be in
intel_dsc_get_bigjoiner_{secondary,primary}.

They already contain the check that the next/prev pipe exists, which
(silly me) I thought was enough.

BR,
Jani.

> +		drm_dbg_kms(&i915->drm,
> +			    "[CRTC:%d:%s] Bigjoiner not available on this pipe\n",
> +			    crtc->base.base.id, crtc->base.name);
> +		return -EINVAL;
> +	}
> +
>  	slave_crtc = intel_dsc_get_bigjoiner_secondary(crtc);
>  	if (!slave_crtc) {
>  		DRM_DEBUG_KMS("[CRTC:%d:%s] Big joiner configuration requires "

-- 
Jani Nikula, Intel Open Source Graphics Center