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

[Nautiyal, Ankit K]

On 7/25/2023 4:49 PM, Nautiyal, Ankit K wrote:
>
> 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 at intel.com>
>>>>> Reviewed-by: Ville Syrjälä <ville.syrjala at 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
>
>
Since we call this function during mode valid too, so cannot directly 
use intel_dsc_get_num_vdsc_instance,

so I have put a comment for clarification about PPC in the latest version.

Regard,

Ankit


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