Re: [Intel-gfx] [PATCH 05/19] drm/i915/dp: Update Bigjoiner interface bits for computing compressed bpp

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

On 7/25/2023 3:43 PM, Lisovskiy, Stanislav wrote:
> On Mon, Jul 24, 2023 at 05:49:11PM +0530, Nautiyal, Ankit K wrote:
>> Hi Stan,
>>
>> Thanks for the reviews ans suggestions. Please my response inline:
>>
>>
>> On 7/20/2023 2:59 PM, Lisovskiy, Stanislav wrote:
>>> On Thu, Jul 13, 2023 at 04:03:32PM +0530, Ankit Nautiyal wrote:
>>>> In Bigjoiner check for DSC, bigjoiner interface bits for DP for
>>>> DISPLAY > 13 is 36 (Bspec: 49259).
>>>>
>>>> v2: Corrected Display ver to 13.
>>>>
>>>> v3: Follow convention for conditional statement. (Ville)
>>>>
>>>> v4: Fix check for display ver. (Ville)
>>>>
>>>> Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
>>>> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
>>>> ---
>>>>    drivers/gpu/drm/i915/display/intel_dp.c | 3 ++-
>>>>    1 file changed, 2 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
>>>> index 19768ac658ba..c1fd448d80e1 100644
>>>> --- a/drivers/gpu/drm/i915/display/intel_dp.c
>>>> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
>>>> @@ -802,8 +802,9 @@ u16 intel_dp_dsc_get_max_compressed_bpp(struct drm_i915_private *i915,
>>>>    	bits_per_pixel = min(bits_per_pixel, max_bpp_small_joiner_ram);
>>>>    	if (bigjoiner) {
>>>> +		int bigjoiner_interface_bits = DISPLAY_VER(i915) >= 14 ? 36 : 24;
>>>>    		u32 max_bpp_bigjoiner =
>>>> -			i915->display.cdclk.max_cdclk_freq * 48 /
>>>> +			i915->display.cdclk.max_cdclk_freq * 2 * bigjoiner_interface_bits /
>>> Probably "num_vdsc_instances = intel_dsc_get_num_vdsc_instances(crtc_state);" again,
>>> instead of "2"?
>> Currently intel_dsc_get_num_vdsc_instances will give total number of
>> vdsc_engines including joined pipes.
>>
>> So with bigjoiner the function will return 4.
>>
>> This was good to calculate Pipe BW check: (Pixel clock < PPC * CDCLK
>> frequency * Number of pipes joined
>>
>> as we get PPC * number of pipes joined from
>> intel_dsc_get_num_vdsc_instances)
>>
>> Or to calculate DSC_PIC_WIDTH PPS parameter.
>>
>> But here we perhaps need intel_dsc_get_vdsc_engines_per_pipe that will just
>> return 2 if dsc_split 1 otherwise.
>>
>> Thanks & Regards,
>>
>> Ankit
> Yes, I agree, unfortunately not applicable here.
> May be yeah we need some function like that and then refactor
> also the intel_dsc_get_num_vdsc_instances to use that one..
>
> Stan

Alright, let me make the change in a separate patch and add to this series.

Thanks & Regards,

Ankit


>
>>> With that clarified,
>>>
>>> Reviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
>>>
>>>>    			intel_dp_mode_to_fec_clock(mode_clock);
>>>>    		bits_per_pixel = min(bits_per_pixel, max_bpp_bigjoiner);
>>>> -- 
>>>> 2.40.1
>>>>