Re: [PATCH 04/15] drm/i915/display: Modify debugfs for joiner to force n pipes

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

On Wed, Sep 18, 2024 at 08:13:32PM +0530, Ankit Nautiyal wrote:
> At the moment, the debugfs for joiner allows only to force enable/disable
> pipe joiner for 2 pipes. Modify it to force join 'n' number of pipes,
> where n is a valid pipe joiner configuration.
> This will help in case of ultra joiner where 4 pipes are joined.
> 
> v2:
> -Fix commit message to state that only valid joiner config can be
> forced. (Suraj)
> -Rename the identifiers to have INTEL_BIG/NONE_JOINER_PIPES. (Suraj)
> v3:
> -Avoid enum for joiner pipe counts, use bare numbers for better
> readability. (Ville)
> -Remove redundant prints from debugfs. (Ville)
> v4:
> -Return -EINVAL if joiner forced to an invalid value.
> 
> Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
> ---
>  .../drm/i915/display/intel_display_debugfs.c  | 63 ++++++++++++++++++-
>  .../drm/i915/display/intel_display_types.h    |  2 +-
>  drivers/gpu/drm/i915/display/intel_dp.c       |  2 +-
>  3 files changed, 63 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_display_debugfs.c b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> index cda3f6cf724d..5775413c6763 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> +++ b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> @@ -1504,6 +1504,65 @@ static int intel_crtc_pipe_show(struct seq_file *m, void *unused)
>  }
>  DEFINE_SHOW_ATTRIBUTE(intel_crtc_pipe);
>  
> +static int i915_joiner_show(struct seq_file *m, void *data)
> +{
> +	struct intel_connector *connector = m->private;
> +
> +	seq_printf(m, "%d\n", connector->force_joined_pipes);
> +
> +	return 0;
> +}
> +
> +static ssize_t i915_joiner_write(struct file *file,
> +				 const char __user *ubuf,
> +				 size_t len, loff_t *offp)
> +{
> +	struct seq_file *m = file->private_data;
> +	struct intel_connector *connector = m->private;
> +	struct intel_display *display = to_intel_display(connector);
> +	int force_join_pipes = 0;

'force_joined_pipes' for consistency

> +	int ret;
> +
> +	if (len == 0)
> +		return 0;
> +
> +	ret = kstrtoint_from_user(ubuf, len, 0, &force_join_pipes);
> +	if (ret < 0)
> +		return ret;
> +
> +	switch (force_join_pipes) {
> +	case 0:
> +		fallthrough;
> +	case 2:
> +		connector->force_joined_pipes = force_join_pipes;
> +		break;
> +	default:
> +		drm_dbg(display->drm, "Ignoring Invalid num of pipes %d for force joining\n",
> +			force_join_pipes);
> +		connector->force_joined_pipes = 0;

I don't think we should do any of that. Just return the error.

> +
> +		return -EINVAL;
> +	}
> +
> +	*offp += len;
> +
> +	return len;
> +}
> +
> +static int i915_joiner_open(struct inode *inode, struct file *file)
> +{
> +	return single_open(file, i915_joiner_show, inode->i_private);
> +}
> +
> +static const struct file_operations i915_joiner_fops = {
> +	.owner = THIS_MODULE,
> +	.open = i915_joiner_open,
> +	.read = seq_read,
> +	.llseek = seq_lseek,
> +	.release = single_release,
> +	.write = i915_joiner_write
> +};
> +
>  /**
>   * intel_connector_debugfs_add - add i915 specific connector debugfs files
>   * @connector: pointer to a registered intel_connector
> @@ -1554,8 +1613,8 @@ void intel_connector_debugfs_add(struct intel_connector *connector)
>  	if (HAS_BIGJOINER(i915) && intel_dp_has_joiner(intel_dp) &&
>  	    (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);
> +		debugfs_create_file("i915_joiner_force_enable", 0644, root,
> +				    connector, &i915_joiner_fops);
>  	}
>  
>  	if (connector_type == DRM_MODE_CONNECTOR_DSI ||
> diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
> index 000ab373c887..2ac2068aefa4 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> @@ -524,7 +524,7 @@ struct intel_connector {
>  
>  	struct intel_dp *mst_port;
>  
> -	bool force_bigjoiner_enable;
> +	int force_joined_pipes;
>  
>  	struct {
>  		struct drm_dp_aux *dsc_decompression_aux;
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index 19f78432cc8f..2e35a81fa6d1 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -1280,7 +1280,7 @@ bool intel_dp_need_joiner(struct intel_dp *intel_dp,
>  		return false;
>  
>  	return clock > i915->display.cdclk.max_dotclk_freq || hdisplay > 5120 ||
> -	       connector->force_bigjoiner_enable;
> +	       connector->force_joined_pipes == 2;
>  }
>  
>  bool intel_dp_has_dsc(const struct intel_connector *connector)
> -- 
> 2.45.2

-- 
Ville Syrjälä
Intel