[Intel-gfx] [PATCH 5/5] drm/i915: Add support for new aspect ratios

[Daniel Vetter]

On Fri, Mar 25, 2016 at 01:47:35PM +0530, Shashank Sharma wrote:
> HDMI 2.0/CEA-861-F introduces two new aspect ratios:
> - 64:27
> - 256:135
> 
> This patch adds support for these aspect ratios in
> I915 driver, at various places.
> 
> Signed-off-by: Shashank Sharma <shashank.sharma at intel.com>

Ok, we discussed this a bit internally and I had some questions. Reading
this series patches make sense up to this one, but here I have a few
questions/comments.

> ---
>  drivers/gpu/drm/drm_modes.c       | 12 ++++++++++++
>  drivers/gpu/drm/i915/intel_hdmi.c |  6 ++++++
>  drivers/gpu/drm/i915/intel_sdvo.c |  6 ++++++
>  3 files changed, 24 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c
> index 6e66136..11f219a 100644
> --- a/drivers/gpu/drm/drm_modes.c
> +++ b/drivers/gpu/drm/drm_modes.c
> @@ -1482,6 +1482,12 @@ void drm_mode_convert_to_umode(struct drm_mode_modeinfo *out,
>  	case HDMI_PICTURE_ASPECT_16_9:
>  		out->flags |= DRM_MODE_FLAG_PAR16_9;
>  		break;
> +	case HDMI_PICTURE_ASPECT_64_27:
> +		out->flags |= DRM_MODE_FLAG_PAR64_27;
> +		break;
> +	case DRM_MODE_PICTURE_ASPECT_256_135:
> +		out->flags |= DRM_MODE_FLAG_PAR256_135;
> +		break;
>  	case HDMI_PICTURE_ASPECT_NONE:
>  	case HDMI_PICTURE_ASPECT_RESERVED:
>  	default:
> @@ -1544,6 +1550,12 @@ int drm_mode_convert_umode(struct drm_display_mode *out,
>  	case DRM_MODE_FLAG_PAR16_9:
>  		out->picture_aspect_ratio |= HDMI_PICTURE_ASPECT_16_9;
>  		break;
> +	case DRM_MODE_FLAG_PAR64_27:
> +		out->picture_aspect_ratio |= HDMI_PICTURE_ASPECT_64_27;
> +		break;
> +	case DRM_MODE_FLAG_PAR256_135:
> +		out->picture_aspect_ratio |= HDMI_PICTURE_ASPECT_256_135;
> +		break;
>  	default:
>  		out->picture_aspect_ratio = HDMI_PICTURE_ASPECT_NONE;
>  	}

Above two parts is core enabling, I guess those should be squashed into
the preceeding patch?

> diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
> index e2dab48..bc8e2c8 100644
> --- a/drivers/gpu/drm/i915/intel_hdmi.c
> +++ b/drivers/gpu/drm/i915/intel_hdmi.c
> @@ -1545,6 +1545,12 @@ intel_hdmi_set_property(struct drm_connector *connector,
>  		case DRM_MODE_PICTURE_ASPECT_16_9:
>  			intel_hdmi->aspect_ratio = HDMI_PICTURE_ASPECT_16_9;
>  			break;
> +		case DRM_MODE_PICTURE_ASPECT_64_27:
> +			intel_hdmi->aspect_ratio = HDMI_PICTURE_ASPECT_64_27;
> +			break;
> +		case DRM_MODE_PICTURE_ASPECT_256_135:
> +			intel_hdmi->aspect_ratio = HDMI_PICTURE_ASPECT_256_135;
> +			break;
>  		default:
>  			return -EINVAL;
>  		}
> diff --git a/drivers/gpu/drm/i915/intel_sdvo.c b/drivers/gpu/drm/i915/intel_sdvo.c
> index fae64bc..370e4f9 100644
> --- a/drivers/gpu/drm/i915/intel_sdvo.c
> +++ b/drivers/gpu/drm/i915/intel_sdvo.c
> @@ -2071,6 +2071,12 @@ intel_sdvo_set_property(struct drm_connector *connector,
>  		case DRM_MODE_PICTURE_ASPECT_16_9:
>  			intel_sdvo->aspect_ratio = HDMI_PICTURE_ASPECT_16_9;
>  			break;
> +		case DRM_MODE_PICTURE_ASPECT_64_27:
> +			intel_sdvo->aspect_ratio = HDMI_PICTURE_ASPECT_64_27;
> +			break;
> +		case DRM_MODE_PICTURE_ASPECT_256_135:
> +			intel_sdvo->aspect_ratio = HDMI_PICTURE_ASPECT_256_135;
> +			break;
>  		default:
>  			return -EINVAL;
>  		}

The trouble with the aspect_ratio prop as currently implemented is that we
currently unconditionally overwrite adjusted_mode->picture_aspect_ratio
with it.

But your patches here move the aspect ratio handling into
drm_mode_modeinfo (uabi) and drm_display_mode (kernel-internal), where it
imo belongs. But we need to figure out how to the interaction with the
property correctly. What's probably needed is a new value in the
aspect_ratio enum called "default", which selects the aspect_ratio from
the mode. Only when userspace overrides (NONE, or one of the CEA aspect
ratios) would we obey the aspect_ratio of the property. Otherwise the
aspect ratio stored in the mode would be lost.

The other bit that I can't find in this series is making sure we compute
the VIC correctly for the new modes. Or does that magically work correctly
since we compare the full mode when selecting VICs?

Thanks, Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch