[RFC 04/13] drm/i915: Capture max frl rate for PCON in dfp cap structure

[Shankar, Uma]

> -----Original Message-----
> From: Nautiyal, Ankit K <ankit.k.nautiyal at intel.com>
> Sent: Thursday, October 15, 2020 4:23 PM
> To: intel-gfx at lists.freedesktop.org
> Cc: dri-devel at lists.freedesktop.org; Shankar, Uma <uma.shankar at intel.com>;
> Kulkarni, Vandita <vandita.kulkarni at intel.com>; ville.syrjala at linux.intel.com;
> Sharma, Swati2 <swati2.sharma at intel.com>
> Subject: [RFC 04/13] drm/i915: Capture max frl rate for PCON in dfp cap structure
> 
> HDMI2.1 PCON advertises Max FRL bandwidth supported by the PCON and by the
> sink.
> 
> This patch captures these in dfp cap structure in intel_dp and uses these to
> prune connector modes that cannot be supported by the PCON and sink FRL
> bandwidth.
> 
> Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal at intel.com>
> ---
>  .../drm/i915/display/intel_display_types.h    |  1 +
>  drivers/gpu/drm/i915/display/intel_dp.c       | 33 +++++++++++++++++--
>  2 files changed, 32 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h
> b/drivers/gpu/drm/i915/display/intel_display_types.h
> index 0b5df8e44966..e2f58d0575a2 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> @@ -1398,6 +1398,7 @@ struct intel_dp {
>  	struct {
>  		int min_tmds_clock, max_tmds_clock;
>  		int max_dotclock;
> +		int pcon_max_frl, sink_max_frl;

Append it with bw or rate.

>  		u8 max_bpc;
>  		bool ycbcr_444_to_420;
>  	} dfp;
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c
> b/drivers/gpu/drm/i915/display/intel_dp.c
> index 0902a9aeeda1..cd6934f28f32 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -683,6 +683,24 @@ intel_dp_mode_valid_downstream(struct
> intel_connector *connector,
>  	const struct drm_display_info *info = &connector->base.display_info;
>  	int tmds_clock;
> 
> +	/* If PCON and HDMI2.1 sink both support FRL MODE, check FRL

Use multi line comment style.

> +	 * bandwidth constraints.
> +	 */
> +	if (intel_dp->dfp.pcon_max_frl) {
> +		int target_bw;
> +		int max_frl_bw;
> +		int bpp = intel_dp_mode_min_output_bpp(&connector->base,
> mode);
> +
> +		target_bw = bpp * DIV_ROUND_UP(target_clock, 1000000);

To avoid any roundup errors, it would be good to multiple max_frl_bw by 1000000 than dividing target_clock

> +
> +		max_frl_bw = min(intel_dp->dfp.pcon_max_frl,
> +				 intel_dp->dfp.sink_max_frl);
> +		if (target_bw > max_frl_bw)
> +			return MODE_CLOCK_HIGH;
> +
> +		return MODE_OK;
> +	}
> +
>  	if (intel_dp->dfp.max_dotclock &&
>  	    target_clock > intel_dp->dfp.max_dotclock)
>  		return MODE_CLOCK_HIGH;
> @@ -6383,13 +6401,21 @@ intel_dp_update_dfp(struct intel_dp *intel_dp,
>  						 intel_dp->downstream_ports,
>  						 edid);
> 
> +	intel_dp->dfp.pcon_max_frl =
> +		drm_dp_get_pcon_max_frl_bw(intel_dp->dpcd,
> +					   intel_dp->downstream_ports);
> +
> +	intel_dp->dfp.sink_max_frl =
> +drm_dp_get_hdmi_max_frl_bw(&intel_dp->aux);
> +
>  	drm_dbg_kms(&i915->drm,
> -		    "[CONNECTOR:%d:%s] DFP max bpc %d, max dotclock %d,
> TMDS clock %d-%d\n",
> +		    "[CONNECTOR:%d:%s] DFP max bpc %d, max dotclock %d,
> TMDS clock
> +%d-%d, PCON Max FRL BW %dGbps, Sink Max FRL BW %dGbps\n",
>  		    connector->base.base.id, connector->base.name,
>  		    intel_dp->dfp.max_bpc,
>  		    intel_dp->dfp.max_dotclock,
>  		    intel_dp->dfp.min_tmds_clock,
> -		    intel_dp->dfp.max_tmds_clock);
> +		    intel_dp->dfp.max_tmds_clock,
> +		    intel_dp->dfp.pcon_max_frl,
> +		    intel_dp->dfp.sink_max_frl);
>  }
> 
>  static void
> @@ -6479,6 +6505,9 @@ intel_dp_unset_edid(struct intel_dp *intel_dp)
>  	intel_dp->dfp.min_tmds_clock = 0;
>  	intel_dp->dfp.max_tmds_clock = 0;
> 
> +	intel_dp->dfp.pcon_max_frl = 0;
> +	intel_dp->dfp.sink_max_frl = 0;
> +
>  	intel_dp->dfp.ycbcr_444_to_420 = false;
>  	connector->base.ycbcr_420_allowed = false;  }
> --
> 2.17.1