Re: [PATCH] drm/i915/hdmi: Detect HDMI 2.0 monitors using multiple EDID capabilities

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

On Wed, Oct 17, 2018 at 04:10:34PM -0700, clinton.a.taylor@intel.com wrote:
> From: Clint Taylor <clinton.a.taylor@intel.com>
> 
> HDMI 2.0 monitors may not support SCDC and still be able to accept VICs
> above 63. Use multiple EDID capbilities to determine if the SINK is
> actually an HDMI 2.0 device. The QD980B HDMI 2.0 Analyzer generates unique
> EDIDs during CTS tests that don't contain a HDMI Forum VSDB if the block is
> not used during the test. The current HDMI AVI infoframe code only uses the
> SCDC supported information in the HDMI Forum VSDB to determine if the sink
> is HDMI 2.0. This patch adds checks for YCbCr420 Deep Color, YCbCR420 VDB,
> YCBCR420 CMDB capabilities, and pipe is YCbCr420 to the existing SCDC
> supported check to Infer SINK is HDMI 2.0.
> 
> HDMI 2.0 CTS HF1-51 test fails on the QD980B.
> 
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=107894
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Cc: Shashank Sharma <shashank.sharma@intel.com>
> 
> Signed-off-by: Clint Taylor <clinton.a.taylor@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_hdmi.c | 32 +++++++++++++++++++++++++++++++-
>  1 file changed, 31 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
> index 2c53efc..6913806 100644
> --- a/drivers/gpu/drm/i915/intel_hdmi.c
> +++ b/drivers/gpu/drm/i915/intel_hdmi.c
> @@ -458,6 +458,34 @@ static void intel_write_infoframe(struct intel_encoder *encoder,
>  					frame->any.type, buffer, len);
>  }
>  
> +static bool is_hdmi2(const struct drm_connector *connector,
> +			const struct intel_crtc_state *crtc_state)
> +{
> +	bool hdmi2 = false;
> +	bool vdb_mode = false;
> +	bool cmdb_mode = false;
> +	int i = 0;
> +
> +	/* check VDB bits for HDMI 2.0 mode */
> +	for (i = 0; i < BITS_TO_LONGS(128); i++)
> +		if (connector->display_info.hdmi.y420_vdb_modes[i])
> +			vdb_mode = true;
> +
> +	/* check CMDB bits for HDMI 2.0 mode */
> +	for (i = 0; i < BITS_TO_LONGS(128); i++)
> +		if (connector->display_info.hdmi.y420_cmdb_modes[i])
> +			cmdb_mode = true;
> +
> +	if (connector->display_info.hdmi.scdc.supported ||
> +	    connector->display_info.hdmi.y420_dc_modes ||
> +	    crtc_state->ycbcr420 || vdb_mode || cmdb_mode) {

I think we can replace all this 4:2:0 related stuff with just a
display_info->color_formats & DRM_COLOR_FORMAT_YCRCB420
check.

> +		DRM_DEBUG_KMS("Inferred HDMI2 sink present\n");
> +		hdmi2 = true;
> +	}
> +
> +	return hdmi2;
> +}
> +
>  static void intel_hdmi_set_avi_infoframe(struct intel_encoder *encoder,
>  					 const struct intel_crtc_state *crtc_state,
>  					 const struct drm_connector_state *conn_state)
> @@ -466,10 +494,12 @@ static void intel_hdmi_set_avi_infoframe(struct intel_encoder *encoder,
>  	const struct drm_display_mode *adjusted_mode =
>  		&crtc_state->base.adjusted_mode;
>  	struct drm_connector *connector = &intel_hdmi->attached_connector->base;
> -	bool is_hdmi2_sink = connector->display_info.hdmi.scdc.supported;
> +	bool is_hdmi2_sink = false;
>  	union hdmi_infoframe frame;
>  	int ret;
>  
> +	is_hdmi2_sink = is_hdmi2(connector, crtc_state);
> +
>  	ret = drm_hdmi_avi_infoframe_from_display_mode(&frame.avi,
>  						       adjusted_mode,
>  						       is_hdmi2_sink);
> -- 
> 1.9.1

-- 
Ville Syrjälä
Intel
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