[PATCH v4 16/16] drm/i915: Enable PCON configuration for Color Conversion for TGL

[Nautiyal, Ankit K]

On 12/13/2020 12:59 PM, Shankar, Uma wrote:
>
>> -----Original Message-----
>> From: Nautiyal, Ankit K <ankit.k.nautiyal at intel.com>
>> Sent: Tuesday, December 8, 2020 1:22 PM
>> To: intel-gfx at lists.freedesktop.org
>> Cc: dri-devel at lists.freedesktop.org; Shankar, Uma <uma.shankar at intel.com>;
>> airlied at linux.ie; jani.nikula at linux.intel.com; ville.syrjala at linux.intel.com;
>> Kulkarni, Vandita <vandita.kulkarni at intel.com>; Sharma, Swati2
>> <swati2.sharma at intel.com>
>> Subject: [PATCH v4 16/16] drm/i915: Enable PCON configuration for Color
>> Conversion for TGL
> Append display here.


Noted. Will change in the next version of the patch.

>> This patch enables PCON configuration for color space conversion for
>> TGL+ platfrom. This will help in supporting 8k at 60 YUV420 modes common
>> in HDMI 8k panels, through a capable PCON.
>> Also allow 8k at 60 YUV420 modes, only if PCON claims to support the color space
>> conversion.
>>
>> Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal at intel.com>
>> ---
>>   drivers/gpu/drm/i915/display/intel_ddi.c | 1 +
>> drivers/gpu/drm/i915/display/intel_dp.c  | 5 +++++
>>   2 files changed, 6 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c
>> b/drivers/gpu/drm/i915/display/intel_ddi.c
>> index 721a47bbc009..ed6b8ea85408 100644
>> --- a/drivers/gpu/drm/i915/display/intel_ddi.c
>> +++ b/drivers/gpu/drm/i915/display/intel_ddi.c
>> @@ -3644,6 +3644,7 @@ static void tgl_ddi_pre_enable_dp(struct
>> intel_atomic_state *state,
>>   	if (!is_mst)
>>   		intel_dp_set_power(intel_dp, DP_SET_POWER_D0);
>>
>> +	intel_dp_configure_protocol_converter(intel_dp);
> Both the changes seems to be unrelated, it would be good to put configuration
> of protocol convertor in earlier patches and just pruning logic here.
> Also the description of patch needs to change to clearly call this out.


Alright. Will split the pruning logic into a separate patch.


>
>>   	intel_dp_sink_set_decompression_state(intel_dp, crtc_state, true);
>>   	/*
>>   	 * DDI FEC: "anticipates enabling FEC encoding sets the FEC_READY bit
>> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c
>> b/drivers/gpu/drm/i915/display/intel_dp.c
>> index b3f1190d8150..86289c925612 100644
>> --- a/drivers/gpu/drm/i915/display/intel_dp.c
>> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
>> @@ -720,6 +720,11 @@ intel_dp_mode_valid_downstream(struct
>> intel_connector *connector,
>>   	const struct drm_display_info *info = &connector->base.display_info;
>>   	int tmds_clock;
>>
>> +	/* Allow 8k YUV420 modes, only if PCON supports RGB->YUV conversion
>> */
>> +	if (mode->hdisplay == 7680 && drm_mode_is_420_only(info, mode) &&
>> +	    !intel_dp->dfp.rgb_to_ycbcr)
> I think this will be a platform limitation, as there may be platforms which can
> do that on the SOC side as well. So would be good to limit to those platforms where
> pcon conversion is the only option in order to support this configuration, instead of doing
> it for all platforms.

We do have a flag  ycbcr_420_allowed which gets set for Gen > 5 and also 
if DP sink has ycbcr420 passthrough or ycbcr444->420 conversion support.

So theoretically we should be able to convert RGB->YCbCR for Gen > 5.

But I am not sure, if we need some changes when we use big joiner.

With Realtek HDMI2.1 dongle, I was able to get RGB->YCbCr and 444->420 
conversion for 8k at 60 YUV420 through PCON.

Probably need to revisit this again.

Thanks & Regards,

Ankit

>
>> +		return MODE_NO_420;
>> +
>>   	/*
>>   	 * If PCON and HDMI2.1 sink both support FRL MODE, check FRL
>>   	 * bandwidth constraints.
>> --
>> 2.17.1