Re: [Intel-gfx] [PATCH v4 07/16] drm/dp_helper: Add helpers to configure PCONs RGB-YCbCr Conversion

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

Hi Uma Shankar,

Thanks for the comments and suggestions.

Please find my response inline.

On 12/13/2020 12:40 PM, Shankar, Uma wrote:
>
>> -----Original Message-----
>> From: Nautiyal, Ankit K <ankit.k.nautiyal@intel.com>
>> Sent: Tuesday, December 8, 2020 1:22 PM
>> To: intel-gfx@lists.freedesktop.org
>> Cc: dri-devel@lists.freedesktop.org; Shankar, Uma <uma.shankar@intel.com>;
>> airlied@linux.ie; jani.nikula@linux.intel.com; ville.syrjala@linux.intel.com;
>> Kulkarni, Vandita <vandita.kulkarni@intel.com>; Sharma, Swati2
>> <swati2.sharma@intel.com>
>> Subject: [PATCH v4 07/16] drm/dp_helper: Add helpers to configure PCONs RGB-
>> YCbCr Conversion
>>
>> DP Specification for DP2.0 to HDMI2.1 Pcon specifies support for conversion of
>> colorspace from RGB to YCbCr.
>> https://groups.vesa.org/wg/DP/document/previewpdf/15651
>>
>> This patch adds the relavant registers and helper functions to get the capability
>> and set the color conversion bits for rgb->ycbcr conversion through PCON.
>>
>> Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
>> ---
>>   drivers/gpu/drm/drm_dp_helper.c | 59 +++++++++++++++++++++++++++++++++
>>   include/drm/drm_dp_helper.h     | 10 +++++-
>>   2 files changed, 68 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/drm_dp_helper.c
>> b/drivers/gpu/drm/drm_dp_helper.c index d0626f57f99c..344662d5c295 100644
>> --- a/drivers/gpu/drm/drm_dp_helper.c
>> +++ b/drivers/gpu/drm/drm_dp_helper.c
>> @@ -949,6 +949,35 @@ bool
>> drm_dp_downstream_444_to_420_conversion(const u8
>> dpcd[DP_RECEIVER_CAP_SIZE]  }
>> EXPORT_SYMBOL(drm_dp_downstream_444_to_420_conversion);
>>
>> +/**
>> + * drm_dp_downstream_rgb_to_ycbcr_conversion() - determine downstream
>> facing port
>> + *                                               RGB->YCbCr conversion capability
>> + * @dpcd: DisplayPort configuration data
>> + * @port_cap: downstream facing port capabilities
>> + *
>> + * Returns: whether the downstream facing port can convert RGB->YCbCr
>> +*/ bool drm_dp_downstream_rgb_to_ycbcr_conversion(const u8
>> +dpcd[DP_RECEIVER_CAP_SIZE],
>> +					       const u8 port_cap[4])
>> +{
>> +	if (!drm_dp_is_branch(dpcd))
>> +		return false;
>> +
>> +	if (dpcd[DP_DPCD_REV] < 0x13)
>> +		return false;
>> +
>> +	switch (port_cap[0] & DP_DS_PORT_TYPE_MASK) {
>> +	case DP_DS_PORT_TYPE_HDMI:
>> +		if ((dpcd[DP_DOWNSTREAMPORT_PRESENT] &
>> DP_DETAILED_CAP_INFO_AVAILABLE) == 0)
>> +			return false;
>> +
>> +		return port_cap[3] & DP_DS_HDMI_BT601_RGB_YCBCR_CONV;
> I guess there are other conversions also possible, like BT709 and 2020. Update those
> as well here.


Yes you are right. I will modify the function to take as input 
colorspace, also and

the function will be returning true, if the rgb->ycbcr conversion for 
the given colorspace is supported.


>
>> +	default:
>> +		return false;
>> +	}
>> +}
>> +EXPORT_SYMBOL(drm_dp_downstream_rgb_to_ycbcr_conversion);
>> +
>>   /**
>>    * drm_dp_downstream_mode() - return a mode for downstream facing port
>>    * @dev: DRM device
>> @@ -3140,3 +3169,33 @@ int drm_dp_pcon_pps_override_param(struct
>> drm_dp_aux *aux, u8 pps_param[6])
>>   	return 0;
>>   }
>>   EXPORT_SYMBOL(drm_dp_pcon_pps_override_param);
>> +
>> +/*
>> + * drm_dp_pcon_convert_rgb_to_ycbcr() - Configure the PCon to convert
>> +RGB to Ycbcr
>> + * @aux: displayPort AUX channel
>> + * @color_spc: Color space conversion type
>> + *
>> + * Returns 0 on success, else returns negative error code.
>> + */
>> +int drm_dp_pcon_convert_rgb_to_ycbcr(struct drm_dp_aux *aux, u8
>> +color_spc) {
>> +	int ret;
>> +	u8 buf;
>> +
>> +	if (color_spc != DP_CONVERSION_BT601_RGB_YCBCR_ENABLE ||
>> +	    color_spc != DP_CONVERSION_BT709_RGB_YCBCR_ENABLE ||
>> +	    color_spc != DP_CONVERSION_BT2020_RGB_YCBCR_ENABLE)
>> +		return -EINVAL;
> Yeah this is wrong, fix it.

Agreed. Will fix this in next version of the patch.

>
>> +
>> +	ret = drm_dp_dpcd_readb(aux, DP_PROTOCOL_CONVERTER_CONTROL_2,
>> &buf);
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	buf |= color_spc;
>> +	ret = drm_dp_dpcd_writeb(aux,
>> DP_PROTOCOL_CONVERTER_CONTROL_2, buf);
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	return 0;
>> +}
>> +EXPORT_SYMBOL(drm_dp_pcon_convert_rgb_to_ycbcr);
>> diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h index
>> 347b4e1a55b4..1b3d54ed7a78 100644
>> --- a/include/drm/drm_dp_helper.h
>> +++ b/include/drm/drm_dp_helper.h
>> @@ -431,6 +431,9 @@ struct drm_device;
>>   # define DP_DS_HDMI_YCBCR420_PASS_THROUGH   (1 << 2)
>>   # define DP_DS_HDMI_YCBCR444_TO_422_CONV    (1 << 3)
>>   # define DP_DS_HDMI_YCBCR444_TO_420_CONV    (1 << 4)
>> +# define DP_DS_HDMI_BT601_RGB_YCBCR_CONV    (1 << 5)
>> +# define DP_DS_HDMI_BT709_RGB_YCBCR_CONV    (1 << 6)
>> +# define DP_DS_HDMI_BT2020_RGB_YCBCR_CONV   (1 << 7)
> I think it would be good to mention the location in spec (section or table),
> will make it easier to understand/review by directly going to relevant sections in spec.

This is still Draft 1 of the spec: VESA DP-to-HDMI PCON Specification 
Standalone Document. Link in the commit message.

I will mention the current Section and Table no. nevertheless in the 
next version of the patch.

Thanks & Regards,

Ankit

>>   #define DP_MAX_DOWNSTREAM_PORTS		    0x10
>>
>> @@ -1217,7 +1220,9 @@ struct drm_device;
>>   # define DP_PCON_ENC_PPS_OVERRIDE_DISABLED      0
>>   # define DP_PCON_ENC_PPS_OVERRIDE_EN_PARAMS     1
>>   # define DP_PCON_ENC_PPS_OVERRIDE_EN_BUFFER     2
>> -
>> +# define DP_CONVERSION_BT601_RGB_YCBCR_ENABLE  (1 << 4) # define
>> +DP_CONVERSION_BT709_RGB_YCBCR_ENABLE  (1 << 5) # define
>> +DP_CONVERSION_BT2020_RGB_YCBCR_ENABLE (1 << 6)
>>
>>   /* PCON Downstream HDMI ERROR Status per Lane */
>>   #define DP_PCON_HDMI_ERROR_STATUS_LN0          0x3037
>> @@ -2178,5 +2183,8 @@ int drm_dp_pcon_dsc_bpp_incr(const u8
>> pcon_dsc_dpcd[DP_PCON_DSC_ENCODER_CAP_SIZE
>>   int drm_dp_pcon_pps_default(struct drm_dp_aux *aux);  int
>> drm_dp_pcon_pps_override_buf(struct drm_dp_aux *aux, u8 pps_buf[128]);  int
>> drm_dp_pcon_pps_override_param(struct drm_dp_aux *aux, u8 pps_param[6]);
>> +bool drm_dp_downstream_rgb_to_ycbcr_conversion(const u8
>> dpcd[DP_RECEIVER_CAP_SIZE],
>> +					       const u8 port_cap[4]);
>> +int drm_dp_pcon_convert_rgb_to_ycbcr(struct drm_dp_aux *aux, u8
>> +color_spc);
>>
>>   #endif /* _DRM_DP_HELPER_H_ */
>> --
>> 2.17.1
_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx