Re: [PATCH 03/19] drm/i915/display_debugfs: Allow force joiner only if supported

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

On Wed, Sep 11, 2024 at 06:43:33PM +0530, Ankit Nautiyal wrote:
> Currently joiner is only supported for DP encoder.
> Allow force joiner only for DP for supported platforms.
> 
> Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
> ---
>  .../drm/i915/display/intel_display_debugfs.c  | 20 ++++++++++++++++---
>  1 file changed, 17 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_display_debugfs.c b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> index d7651f6f80e1..7ceaf01a884a 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> +++ b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> @@ -1520,6 +1520,9 @@ static ssize_t i915_joiner_write(struct file *file,
>  	struct seq_file *m = file->private_data;
>  	struct intel_connector *connector = m->private;
>  	struct intel_display *display = to_intel_display(connector);
> +	struct intel_encoder *intel_encoder = intel_attached_encoder(connector);

That won't work for MST. You'll want to use intel_attached_dp().

> +	struct intel_dp *intel_dp;
> +	int connector_type = connector->base.connector_type;
>  	int force_join_pipes = 0;
>  	int ret;
>  
> @@ -1530,16 +1533,27 @@ static ssize_t i915_joiner_write(struct file *file,
>  	if (ret < 0)
>  		return ret;
>  
> +	/* Currently joiner is only supported for eDP/DP */
> +	if (connector_type != DRM_MODE_CONNECTOR_DisplayPort &&
> +	    connector_type != DRM_MODE_CONNECTOR_eDP)
> +		return 0;

We shouldn't be adding the debugfs file to a non-DP connector so this
seems redundant.

> +
> +	intel_dp = enc_to_intel_dp(intel_encoder);
> +
> +	connector->force_joined_pipes = 0;
> +
>  	switch (force_join_pipes) {
>  	case 0:
> -		fallthrough;
> +		break;
>  	case 2:
> -		connector->force_joined_pipes = force_join_pipes;
> +		if (intel_dp_has_joiner(intel_dp))
> +			connector->force_joined_pipes = force_join_pipes;
> +		else
> +			drm_dbg(display->drm, "Force joiner not supported for the config\n");

That should return an error. Hmm, or perhaps even better to not
even create the debugfs file in the first place?

>  		break;
>  	default:
>  		drm_dbg(display->drm, "Ignoring Invalid num of pipes %d for force joining\n",
>  			force_join_pipes);
> -		connector->force_joined_pipes = 0;
>  	}
>  
>  	*offp += len;
> -- 
> 2.45.2

-- 
Ville Syrjälä
Intel