Re: [PATCH 10/23] drm/i915/dp: Allow big joiner modes in intel_dp_mode_valid()

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On Tue, Sep 24, 2019 at 10:30:39PM -0700, Matt Roper wrote:
> On Fri, Sep 20, 2019 at 01:42:22PM +0200, Maarten Lankhorst wrote:
> > Small changes to intel_dp_mode_valid(), allow listing modes that
> > can only be supported in the bigjoiner configuration, which is
> > not supported yet.
> > 
> > Also unexport a few functions only used internally in intel_dp.c
> > 
> > Signed-off-by: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
> > ---
> >  drivers/gpu/drm/i915/display/intel_dp.c | 98 +++++++++++++++++++------
> >  1 file changed, 75 insertions(+), 23 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> > index 2fceb71f7f70..046e1662d1e3 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> > @@ -247,7 +247,7 @@ intel_dp_max_data_rate(int max_link_clock, int max_lanes)
> >  }
> >  
> >  static int
> > -intel_dp_downstream_max_dotclock(struct intel_dp *intel_dp)
> > +intel_dp_downstream_max_dotclock(struct intel_dp *intel_dp, bool allow_bigjoiner)
> >  {
> >  	struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp);
> >  	struct intel_encoder *encoder = &intel_dig_port->base;
> > @@ -257,6 +257,9 @@ intel_dp_downstream_max_dotclock(struct intel_dp *intel_dp)
> >  
> >  	int type = intel_dp->downstream_ports[0] & DP_DS_PORT_TYPE_MASK;
> >  
> > +	if (allow_bigjoiner && INTEL_GEN(dev_priv) >= 11)
> > +		max_dotclk *= 2;
> > +
> 
> Should we be checking if the specific pipe can do big joiner on the
> platform (gen11 vs gen12 differences) and also omitting eDP from
> consideration?
> 
> 
> >  	if (type != DP_DS_PORT_TYPE_VGA)
> >  		return max_dotclk;
> >  
> > @@ -505,8 +508,10 @@ u32 intel_dp_fec_to_mode_clock(u32 fec_clock)
> >  		       1000000U);
> >  }
> >  
> > -static u16 intel_dp_dsc_get_output_bpp(u32 link_clock, u32 lane_count,
> > -				       u32 mode_clock, u32 mode_hdisplay)
> > +static u16 intel_dp_dsc_get_output_bpp(struct drm_i915_private *dev_priv,
> > +				       u32 link_clock, u32 lane_count,
> > +				       u32 mode_clock, u32 mode_hdisplay,
> > +				       bool bigjoiner)
> >  {
> >  	u32 bits_per_pixel, max_bpp_small_joiner_ram;
> >  	int i;
> > @@ -523,6 +528,10 @@ static u16 intel_dp_dsc_get_output_bpp(u32 link_clock, u32 lane_count,
> >  
> >  	/* Small Joiner Check: output bpp <= joiner RAM (bits) / Horiz. width */
> >  	max_bpp_small_joiner_ram = DP_DSC_MAX_SMALL_JOINER_RAM_BUFFER / mode_hdisplay;
> > +
> > +	if (bigjoiner)
> > +		max_bpp_small_joiner_ram *= 2;
> > +
> 
> This change is correct, but while confirming in the bspec I noticed that
> we may have the wrong DP_DSC_MAX_SMALL_JOINER_RAM_BUFFER value for
> gen11+.  It indicates 6144 for GLK, CNL, but 7680 for ICL+ (and double
> that to 15360 when using big joiner).

Sorry, meant to say wrong value for < gen11.  The current 61440 value we
use is 8 bits * 7680, so it's correct for gen11+, but too big for
GLK/CNL.

I just sent a simple patch to make the value platform-specific:
        https://patchwork.freedesktop.org/series/67195/


Matt

> 
> Bspec: 20388
> Bspec: 49259
> 
> >  	DRM_DEBUG_KMS("Max small joiner bpp: %u\n", max_bpp_small_joiner_ram);
> >  
> >  	/*
> > @@ -531,6 +540,15 @@ static u16 intel_dp_dsc_get_output_bpp(u32 link_clock, u32 lane_count,
> >  	 */
> >  	bits_per_pixel = min(bits_per_pixel, max_bpp_small_joiner_ram);
> >  
> > +	if (bigjoiner) {
> > +		u32 max_bpp_bigjoiner =
> > +			dev_priv->max_cdclk_freq * 48 /
> > +			intel_dp_mode_to_fec_clock(mode_clock);
> 
> Minor nitpick, but just to match the bspec (PPC * CDCLK * 24 bits /
> pixel clock), I'd keep the 2 PPC and 24 bit factors separate here.
> 
> > +
> > +		DRM_DEBUG_KMS("Max big joiner bpp: %u\n", max_bpp_bigjoiner);
> > +		bits_per_pixel = min(bits_per_pixel, max_bpp_bigjoiner);
> > +	}
> > +
> >  	/* Error out if the max bpp is less than smallest allowed valid bpp */
> >  	if (bits_per_pixel < valid_dsc_bpp[0]) {
> >  		DRM_DEBUG_KMS("Unsupported BPP %u, min %u\n",
> > @@ -553,7 +571,8 @@ static u16 intel_dp_dsc_get_output_bpp(u32 link_clock, u32 lane_count,
> >  }
> >  
> >  static u8 intel_dp_dsc_get_slice_count(struct intel_dp *intel_dp,
> > -				       int mode_clock, int mode_hdisplay)
> > +				       int mode_clock, int mode_hdisplay,
> > +				       bool bigjoiner)
> >  {
> >  	u8 min_slice_count, i;
> >  	int max_slice_width;
> > @@ -578,12 +597,20 @@ static u8 intel_dp_dsc_get_slice_count(struct intel_dp *intel_dp,
> >  
> >  	/* Find the closest match to the valid slice count values */
> >  	for (i = 0; i < ARRAY_SIZE(valid_dsc_slicecount); i++) {
> > -		if (valid_dsc_slicecount[i] >
> > -		    drm_dp_dsc_sink_max_slice_count(intel_dp->dsc_dpcd,
> > -						    false))
> > +		u8 test_slice_count = bigjoiner ?
> > +			2 * valid_dsc_slicecount[i] :
> > +			valid_dsc_slicecount[i];
> > +
> > +		if (test_slice_count >
> > +		    drm_dp_dsc_sink_max_slice_count(intel_dp->dsc_dpcd, false))
> >  			break;
> > -		if (min_slice_count  <= valid_dsc_slicecount[i])
> > -			return valid_dsc_slicecount[i];
> > +
> > +		/* big joiner needs small joiner to be enabled */
> > +		if (bigjoiner && test_slice_count < 4)
> > +			continue;
> > +
> > +		if (min_slice_count <= test_slice_count)
> > +			return test_slice_count;
> >  	}
> >  
> >  	DRM_DEBUG_KMS("Unsupported Slice Count %d\n", min_slice_count);
> > @@ -603,11 +630,15 @@ intel_dp_mode_valid(struct drm_connector *connector,
> >  	int max_dotclk;
> >  	u16 dsc_max_output_bpp = 0;
> >  	u8 dsc_slice_count = 0;
> > +	bool dsc = false, bigjoiner = false;
> >  
> >  	if (mode->flags & DRM_MODE_FLAG_DBLSCAN)
> >  		return MODE_NO_DBLESCAN;
> >  
> > -	max_dotclk = intel_dp_downstream_max_dotclock(intel_dp);
> > +	if (mode->flags & DRM_MODE_FLAG_DBLCLK)
> > +		return MODE_H_ILLEGAL;
> > +
> > +	max_dotclk = intel_dp_downstream_max_dotclock(intel_dp, false);
> >  
> >  	if (intel_dp_is_edp(intel_dp) && fixed_mode) {
> >  		if (mode->hdisplay > fixed_mode->hdisplay)
> > @@ -619,6 +650,18 @@ intel_dp_mode_valid(struct drm_connector *connector,
> >  		target_clock = fixed_mode->clock;
> >  	}
> >  
> > +	if (mode->clock < 10000)
> > +		return MODE_CLOCK_LOW;
> > +
> > +	if (target_clock > max_dotclk) {
> > +		max_dotclk = intel_dp_downstream_max_dotclock(intel_dp, true);
> > +
> > +		if (target_clock > max_dotclk)
> > +			return MODE_CLOCK_HIGH;
> > +
> > +		bigjoiner = true;
> > +	}
> > +
> >  	max_link_clock = intel_dp_max_link_rate(intel_dp);
> >  	max_lanes = intel_dp_max_lane_count(intel_dp);
> >  
> > @@ -639,26 +682,32 @@ intel_dp_mode_valid(struct drm_connector *connector,
> >  								true);
> >  		} else if (drm_dp_sink_supports_fec(intel_dp->fec_capable)) {
> >  			dsc_max_output_bpp =
> > -				intel_dp_dsc_get_output_bpp(max_link_clock,
> > +				intel_dp_dsc_get_output_bpp(dev_priv,
> > +							    max_link_clock,
> >  							    max_lanes,
> >  							    target_clock,
> > -							    mode->hdisplay) >> 4;
> > +							    mode->hdisplay,
> > +							    bigjoiner) >> 4;
> >  			dsc_slice_count =
> >  				intel_dp_dsc_get_slice_count(intel_dp,
> >  							     target_clock,
> > -							     mode->hdisplay);
> > +							     mode->hdisplay,
> > +							     bigjoiner);
> >  		}
> > +
> > +		dsc = dsc_max_output_bpp && dsc_slice_count;
> >  	}
> >  
> > -	if ((mode_rate > max_rate && !(dsc_max_output_bpp && dsc_slice_count)) ||
> > -	    target_clock > max_dotclk)
> > +	/* big joiner configuration needs DSC */
> > +	if (bigjoiner && !dsc) {
> > +		DRM_DEBUG_KMS("Link clock needs bigjoiner, but DSC or FEC not available\n");
> >  		return MODE_CLOCK_HIGH;
> > +	}
> 
> Somewhere in this function we probably also need to make sure that the
> big joiner is available on the pipe and that we're not using eDP.
> 
> 
> Matt
> 
> >  
> > -	if (mode->clock < 10000)
> > -		return MODE_CLOCK_LOW;
> > -
> > -	if (mode->flags & DRM_MODE_FLAG_DBLCLK)
> > -		return MODE_H_ILLEGAL;
> > +	if (mode_rate > max_rate && !dsc) {
> > +		DRM_DEBUG_KMS("Cannot drive without DSC\n");
> > +		return MODE_CLOCK_HIGH;
> > +	}
> >  
> >  	return intel_mode_valid_max_plane_size(dev_priv, mode);
> >  }
> > @@ -2068,14 +2117,17 @@ static int intel_dp_dsc_compute_config(struct intel_dp *intel_dp,
> >  		u8 dsc_dp_slice_count;
> >  
> >  		dsc_max_output_bpp =
> > -			intel_dp_dsc_get_output_bpp(pipe_config->port_clock,
> > +			intel_dp_dsc_get_output_bpp(dev_priv,
> > +						    pipe_config->port_clock,
> >  						    pipe_config->lane_count,
> >  						    adjusted_mode->crtc_clock,
> > -						    adjusted_mode->crtc_hdisplay);
> > +						    adjusted_mode->crtc_hdisplay,
> > +						    false);
> >  		dsc_dp_slice_count =
> >  			intel_dp_dsc_get_slice_count(intel_dp,
> >  						     adjusted_mode->crtc_clock,
> > -						     adjusted_mode->crtc_hdisplay);
> > +						     adjusted_mode->crtc_hdisplay,
> > +						     false);
> >  		if (!dsc_max_output_bpp || !dsc_dp_slice_count) {
> >  			DRM_DEBUG_KMS("Compressed BPP/Slice Count not supported\n");
> >  			return -EINVAL;
> > -- 
> > 2.20.1
> > 
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
> > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 
> -- 
> Matt Roper
> Graphics Software Engineer
> VTT-OSGC Platform Enablement
> Intel Corporation
> (916) 356-2795
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Matt Roper
Graphics Software Engineer
VTT-OSGC Platform Enablement
Intel Corporation
(916) 356-2795
_______________________________________________
Intel-gfx mailing list
Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
https://lists.freedesktop.org/mailman/listinfo/intel-gfx




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