Re: [Intel-gfx] [PATCH 2/2] drm/i915/dp: Use current cdclk for DSC Bigjoiner BW check

["Nautiyal, Ankit K" <ankit.k.nautiyal@intel.com>]

On 3/29/2023 4:23 PM, Ville Syrjälä wrote:
> On Wed, Mar 29, 2023 at 04:06:21PM +0530, Nautiyal, Ankit K wrote:
>> On 3/29/2023 3:27 PM, Ville Syrjälä wrote:
>>> On Wed, Mar 29, 2023 at 02:14:49PM +0530, Ankit Nautiyal wrote:
>>>> As per Bspec, Big Joiner BW check is:
>>>> Output bpp <= PPC * CDCLK frequency * Big joiner interface bits /
>>>> Pixel clock
>>>>
>>>> Currently we always use max_cdclk in the check for both modevalid
>>>> and compute config steps.
>>>>
>>>> During modevalid use max_cdclk_freq for the check.
>>>> During compute config step use current cdclk for the check.
>>> Nak. cdclk is computed much later based on what is actually needed.
>>> The cdclk freq you are using here is essentially a random number.
>> Oh I didn't realise that, perhaps I was lucky when I tested this.
>>
>> So this check where CDCLK is mentioned, actually expects max_cdclk_freq?
>>
>> If it doesnt then, we might have a compressed_bpp value, that might be
>> violating the big joiner bw check.
>>
>> Should this be handled while computing cdclk?
> Yes. I suggest adding something like intel_vdsc_min_cdclk() that
> handles all of it.


I can try that out.

Will also add *Pipe BW check*: Pixel clock < PPC * CDCLK frequency * 
Number of pipes joined, which seems to be missing.

So with pipe bw_check cdclk should be >  Pixel clock / (PPC * Number of 
pipes joined)

In addition, as per bigjoiner check it should be >= compressed_bpp / 
(PPC * bigjoiner interface bits).

Regards,

Ankit

>> Regards,
>>
>> Ankit
>>
>>>> Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
>>>> ---
>>>>    drivers/gpu/drm/i915/display/intel_dp.c     | 9 ++++++---
>>>>    drivers/gpu/drm/i915/display/intel_dp.h     | 1 +
>>>>    drivers/gpu/drm/i915/display/intel_dp_mst.c | 1 +
>>>>    3 files changed, 8 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
>>>> index 3fe651a8f5d0..d6600de1ab49 100644
>>>> --- a/drivers/gpu/drm/i915/display/intel_dp.c
>>>> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
>>>> @@ -711,6 +711,7 @@ u32 intel_dp_dsc_nearest_valid_bpp(struct drm_i915_private *i915, u32 bpp, u32 p
>>>>    u16 intel_dp_dsc_get_output_bpp(struct drm_i915_private *i915,
>>>>    				u32 link_clock, u32 lane_count,
>>>>    				u32 mode_clock, u32 mode_hdisplay,
>>>> +				unsigned int cdclk,
>>>>    				bool bigjoiner,
>>>>    				u32 pipe_bpp,
>>>>    				u32 timeslots)
>>>> @@ -757,9 +758,9 @@ u16 intel_dp_dsc_get_output_bpp(struct drm_i915_private *i915,
>>>>    
>>>>    	if (bigjoiner) {
>>>>    		int bigjoiner_interface_bits = DISPLAY_VER(i915) <= 12 ? 24 : 36;
>>>> -		u32 max_bpp_bigjoiner =
>>>> -			i915->display.cdclk.max_cdclk_freq * 2 * bigjoiner_interface_bits /
>>>> -			intel_dp_mode_to_fec_clock(mode_clock);
>>>> +
>>>> +		u32 max_bpp_bigjoiner = cdclk * 2 * bigjoiner_interface_bits /
>>>> +					intel_dp_mode_to_fec_clock(mode_clock);
>>>>    
>>>>    		bits_per_pixel = min(bits_per_pixel, max_bpp_bigjoiner);
>>>>    	}
>>>> @@ -1073,6 +1074,7 @@ intel_dp_mode_valid(struct drm_connector *_connector,
>>>>    							    max_lanes,
>>>>    							    target_clock,
>>>>    							    mode->hdisplay,
>>>> +							    dev_priv->display.cdclk.max_cdclk_freq,
>>>>    							    bigjoiner,
>>>>    							    pipe_bpp, 64) >> 4;
>>>>    			dsc_slice_count =
>>>> @@ -1580,6 +1582,7 @@ int intel_dp_dsc_compute_config(struct intel_dp *intel_dp,
>>>>    							    pipe_config->lane_count,
>>>>    							    adjusted_mode->crtc_clock,
>>>>    							    adjusted_mode->crtc_hdisplay,
>>>> +							    dev_priv->display.cdclk.hw.cdclk,
>>>>    							    pipe_config->bigjoiner_pipes,
>>>>    							    pipe_bpp,
>>>>    							    timeslots);
>>>> diff --git a/drivers/gpu/drm/i915/display/intel_dp.h b/drivers/gpu/drm/i915/display/intel_dp.h
>>>> index ef39e4f7a329..d150bfe8abf4 100644
>>>> --- a/drivers/gpu/drm/i915/display/intel_dp.h
>>>> +++ b/drivers/gpu/drm/i915/display/intel_dp.h
>>>> @@ -106,6 +106,7 @@ int intel_dp_dsc_compute_bpp(struct intel_dp *intel_dp, u8 dsc_max_bpc);
>>>>    u16 intel_dp_dsc_get_output_bpp(struct drm_i915_private *i915,
>>>>    				u32 link_clock, u32 lane_count,
>>>>    				u32 mode_clock, u32 mode_hdisplay,
>>>> +				unsigned int cdclk,
>>>>    				bool bigjoiner,
>>>>    				u32 pipe_bpp,
>>>>    				u32 timeslots);
>>>> diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c
>>>> index a860cbc5dbea..266e31b78729 100644
>>>> --- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
>>>> +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
>>>> @@ -925,6 +925,7 @@ intel_dp_mst_mode_valid_ctx(struct drm_connector *connector,
>>>>    							    max_lanes,
>>>>    							    target_clock,
>>>>    							    mode->hdisplay,
>>>> +							    dev_priv->display.cdclk.max_cdclk_freq,
>>>>    							    bigjoiner,
>>>>    							    pipe_bpp, 64) >> 4;
>>>>    			dsc_slice_count =
>>>> -- 
>>>> 2.25.1