[Intel-gfx] [PATCH v4 3/3] drm/i915/dp: Expose connector VRR info via debugfs

[Daniel Vetter]

On Mon, Apr 13, 2020 at 10:08:07PM -0700, Manasi Navare wrote:
> From: Bhanuprakash Modem <bhanuprakash.modem at intel.com>
> 
> [Why]
> It's useful to know the min and max vrr range for IGT testing.
> 
> [How]
> Expose the min and max vfreq for the connector via a debugfs file
> on the connector, "i915_vrr_info".
> 
> Example usage: cat /sys/kernel/debug/dri/0/DP-1/i915_vrr_info
> 
> v3:
> * Remove the unnecessary debug print (Manasi)
> v2:
> * Fix the typo in max_vfreq (Manasi)
> * Change the name of node to i915_vrr_info so we can add
> other vrr info for more debug info (Manasi)
> * Change the VRR capable to display Yes or No (Manasi)
> * Fix indentation checkpatch errors (Manasi)
> 
> Signed-off-by: Bhanuprakash Modem <bhanuprakash.modem at intel.com>
> Signed-off-by: Manasi Navare <manasi.d.navare at intel.com>
> Cc: Jani Nikula <jani.nikula at linux.intel.com>
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Tested-by: Manasi Navare <manasi.d.navare at intel.com>

So if I'm understanding things correctly AMD butchered the VRR stuff and
only exposes it when:

- VRR_ENABLED is set
- _and_ you're using the legacy page_flip path, atomic flip doesn't
  support it
- _and_ the PAGE_FLIP_ASYNC flag is set.

That's pretty bonkers uapi, and I think before we add a new driver we need
to figure out how to make this work. Works case we might need a revert
hammer for the amdgpu side and new VRR properties so we're not tricking
any existing userspace into something where stuff then would break.

But I'm hoping we can do a bit more clever than that. Or maybe I'm just
wrong on how amdgpu vrr works.

Adding amd folks.
-Daniel

> ---
>  .../drm/i915/display/intel_display_debugfs.c  | 22 ++++++++++++++++++-
>  1 file changed, 21 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_display_debugfs.c b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> index bdeea2e02642..35b229ab4d19 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> +++ b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> @@ -2096,6 +2096,21 @@ static const struct file_operations i915_dsc_fec_support_fops = {
>  	.write = i915_dsc_fec_support_write
>  };
>  
> +static int i915_vrr_info_show(struct seq_file *m, void *data)
> +{
> +	struct drm_connector *connector = m->private;
> +
> +	if (connector->status != connector_status_connected)
> +		return -ENODEV;
> +
> +	seq_printf(m, "Vrr_capable: %s\n", yesno(intel_dp_is_vrr_capable(connector)));
> +	seq_printf(m, "Min: %u\n", (u8)connector->display_info.monitor_range.min_vfreq);
> +	seq_printf(m, "Max: %u\n", (u8)connector->display_info.monitor_range.max_vfreq);
> +
> +	return 0;
> +}
> +DEFINE_SHOW_ATTRIBUTE(i915_vrr_info);
> +
>  /**
>   * intel_connector_debugfs_add - add i915 specific connector debugfs files
>   * @connector: pointer to a registered drm_connector
> @@ -2130,9 +2145,14 @@ int intel_connector_debugfs_add(struct drm_connector *connector)
>  
>  	if (INTEL_GEN(dev_priv) >= 10 &&
>  	    (connector->connector_type == DRM_MODE_CONNECTOR_DisplayPort ||
> -	     connector->connector_type == DRM_MODE_CONNECTOR_eDP))
> +	     connector->connector_type == DRM_MODE_CONNECTOR_eDP)) {
>  		debugfs_create_file("i915_dsc_fec_support", S_IRUGO, root,
>  				    connector, &i915_dsc_fec_support_fops);
>  
> +		if (INTEL_GEN(dev_priv) >= 12)
> +			debugfs_create_file("i915_vrr_info", S_IRUGO,
> +					    root, connector, &i915_vrr_info_fops);
> +	}
> +
>  	return 0;
>  }
> -- 
> 2.19.1
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch