Re: [PATCH v9 01/24] drm/dsc: Modify DRM helper to return complete DSC color depth capabilities

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Tue, Nov 13, 2018 at 05:52:09PM -0800, Manasi Navare wrote:
> DSC DPCD color depth register advertises its color depth capabilities
> by setting each of the bits that corresponding to a specific color
> depth. This patch defines those specific color depths and adds
> a helper to return an array of color depth capabilities.
> 
> Signed-off-by: Manasi Navare <manasi.d.navare@intel.com>
> Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
> ---
>  drivers/gpu/drm/drm_dp_helper.c | 29 +++++++++++++++++++----------
>  include/drm/drm_dp_helper.h     |  9 +++++----
>  2 files changed, 24 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
> index 6d483487f2b4..286567063960 100644
> --- a/drivers/gpu/drm/drm_dp_helper.c
> +++ b/drivers/gpu/drm/drm_dp_helper.c
> @@ -1428,17 +1428,26 @@ u8 drm_dp_dsc_sink_line_buf_depth(const u8 dsc_dpcd[DP_DSC_RECEIVER_CAP_SIZE])
>  }
>  EXPORT_SYMBOL(drm_dp_dsc_sink_line_buf_depth);
>  
> -u8 drm_dp_dsc_sink_max_color_depth(const u8 dsc_dpcd[DP_DSC_RECEIVER_CAP_SIZE])
> +void drm_dp_dsc_sink_color_depth_cap(const u8 dsc_dpcd[DP_DSC_RECEIVER_CAP_SIZE],
> +				     u8 *dsc_sink_color_depth_cap)
>  {
> +	int i, cnt = 0;
>  	u8 color_depth = dsc_dpcd[DP_DSC_DEC_COLOR_DEPTH_CAP - DP_DSC_SUPPORT];
>  
> -	if (color_depth & DP_DSC_12_BPC)
> -		return 12;
> -	if (color_depth & DP_DSC_10_BPC)
> -		return 10;
> -	if (color_depth & DP_DSC_8_BPC)
> -		return 8;
> -
> -	return 0;
> +	for (i = 1; i <= 3; i++) {
> +		if (!(color_depth & BIT(i)))
> +			continue;
> +		switch (i) {
> +		case 1:
> +			dsc_sink_color_depth_cap[cnt++] = DP_DSC_8_BPC;
> +			break;
> +		case 2:
> +			dsc_sink_color_depth_cap[cnt++] = DP_DSC_10_BPC;
> +			break;
> +		case 3:
> +			dsc_sink_color_depth_cap[cnt++] = DP_DSC_12_BPC;
> +			break;
> +		}
> +	}
>  }
> -EXPORT_SYMBOL(drm_dp_dsc_sink_max_color_depth);
> +EXPORT_SYMBOL(drm_dp_dsc_sink_color_depth_cap);
> diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
> index 3314e91f6eb3..ea3233b0a790 100644
> --- a/include/drm/drm_dp_helper.h
> +++ b/include/drm/drm_dp_helper.h
> @@ -242,9 +242,9 @@
>  # define DP_DSC_YCbCr420_Native             (1 << 4)
>  
>  #define DP_DSC_DEC_COLOR_DEPTH_CAP          0x06A
> -# define DP_DSC_8_BPC                       (1 << 1)
> -# define DP_DSC_10_BPC                      (1 << 2)
> -# define DP_DSC_12_BPC                      (1 << 3)
> +# define DP_DSC_8_BPC                       8
> +# define DP_DSC_10_BPC                      10
> +# define DP_DSC_12_BPC                      12


I'd suggest something simpler like:

int foo(u8 bpc[3])
{
	int num_bpc = 0;

	if (color_depth & DP_DSC_12_BPC)
		bpc[num_bpc++] = 12;
	if (color_depth & DP_DSC_10_BPC)
		bpc[num_bpc++] = 10;
	if (color_depth & DP_DSC_8_BPC)
		bpc[num_bpc++] = 8;

	return num_bpc;
}

>  
>  #define DP_DSC_PEAK_THROUGHPUT              0x06B
>  # define DP_DSC_THROUGHPUT_MODE_0_MASK      (0xf << 0)
> @@ -1123,7 +1123,8 @@ drm_dp_is_branch(const u8 dpcd[DP_RECEIVER_CAP_SIZE])
>  u8 drm_dp_dsc_sink_max_slice_count(const u8 dsc_dpcd[DP_DSC_RECEIVER_CAP_SIZE],
>  				   bool is_edp);
>  u8 drm_dp_dsc_sink_line_buf_depth(const u8 dsc_dpcd[DP_DSC_RECEIVER_CAP_SIZE]);
> -u8 drm_dp_dsc_sink_max_color_depth(const u8 dsc_dpc[DP_DSC_RECEIVER_CAP_SIZE]);
> +void drm_dp_dsc_sink_color_depth_cap(const u8 dsc_dpc[DP_DSC_RECEIVER_CAP_SIZE],
> +				     u8 *dsc_sink_color_depth_cap);
>  
>  static inline bool
>  drm_dp_sink_supports_dsc(const u8 dsc_dpcd[DP_DSC_RECEIVER_CAP_SIZE])
> -- 
> 2.19.1

-- 
Ville Syrjälä
Intel
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