Re: [PATCH 3/3] drm/i915: Check HDMI TMDS clock rate from DPCD

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

On Tue, May 03, 2016 at 02:46:38PM +0300, Mika Kahola wrote:
> Read TMDS clock rate from DPCD for HDMI to filter out
> modes that might require higher TMDS clock rate than
> supported.
> 
> Signed-off-by: Mika Kahola <mika.kahola@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_dp.c   | 3 +++
>  drivers/gpu/drm/i915/intel_drv.h  | 1 +
>  drivers/gpu/drm/i915/intel_hdmi.c | 7 ++++---
>  3 files changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 74a04ce..0fd078c 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -4591,6 +4591,9 @@ static void intel_dp_get_dfp(struct intel_dp *intel_dp)
>  		if (intel_dp->dfp.type & DP_DS_PORT_TYPE_VGA) {
>  			intel_dp->dfp.dot_clk = dfp_info[1] * 8 * 1000;
>  			DRM_DEBUG_KMS("max pixel rate for VGA is %d kHz\n", intel_dp->dfp.dot_clk);
> +		} else if (!(intel_dp->dfp.type & DP_DS_PORT_TYPE_WIRELESS)) {
> +			intel_dp->dfp.tmds_clk = DIV_ROUND_CLOSEST(dfp_info[1] * 25 * 1000, 10);
> +			DRM_DEBUG_KMS("max TMDS clock is %d kHz\n", intel_dp->dfp.tmds_clk);
>  		}
>  	}
>  }
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index 9798a59..8bf97da 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -799,6 +799,7 @@ struct intel_dp_dfp {
>  	int type;
>  	bool detailed_cap_info;
>  	int dot_clk; /* pixel rate for VGA dongles */
> +	int tmds_clk;
>  };
>  
>  struct intel_dp {
> diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
> index e1012d6..70e8e17 100644
> --- a/drivers/gpu/drm/i915/intel_hdmi.c
> +++ b/drivers/gpu/drm/i915/intel_hdmi.c
> @@ -1170,13 +1170,14 @@ static void pch_post_disable_hdmi(struct intel_encoder *encoder)
>  static int hdmi_port_clock_limit(struct intel_hdmi *hdmi, bool respect_dvi_limit)
>  {
>  	struct drm_device *dev = intel_hdmi_to_dev(hdmi);
> +	int tmds_clock = hdmi_to_dig_port(hdmi)->dp.dfp.tmds_clk;
>  
>  	if ((respect_dvi_limit && !hdmi->has_hdmi_sink) || IS_G4X(dev))
> -		return 165000;
> +		return (tmds_clock > 0 ? min(165000, tmds_clock) : 165000);
>  	else if (IS_HASWELL(dev) || INTEL_INFO(dev)->gen >= 8)
> -		return 300000;
> +		return (tmds_clock > 0 ? min(300000, tmds_clock) : 300000);
>  	else
> -		return 225000;
> +		return (tmds_clock > 0 ? min(225000, tmds_clock) : 225000);

Changing limits for native HDMI ports isn't going to do much when
dealing with active DP dongles.

>  }
>  
>  static enum drm_mode_status
> -- 
> 1.9.1
> 
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-- 
Ville Syrjälä
Intel OTC
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