[PATCH v4 05/25] drm/i915/dp: Add helpers for Compressed BPP and Slice Count for DSC
Singh, Gaurav K
gaurav.k.singh at intel.com
Fri Sep 14 05:57:56 UTC 2018
On 9/12/2018 6:25 AM, Manasi Navare wrote:
> This patch adds helpers for calculating the maximum compressed BPP
> supported with small joiner.
> This also adds a helper for calculating the slice count in case
> of small joiner.
> These are inside intel_dp since they take into account hardware
> limitations.
>
> v6:
> * Take mode_clock and mode_hdisplay as input arguments
> so that this can be called in intel_dp_mode_valid (Manasi)
> v5:
> * Get the max slice width from DPCD
> * Check against Min_Slice_width of 2560 (Anusha)
> v4:
> * #defines for PPR in slice count helper (Gaurav)
> v3:
> * Simply logic for bpp (DK)
> * Limit the valid slice count by max supported by Sink (Manasi)
> v2:
> * Change the small joiner RAM buffer constant as bspec changed (Manasi)
> * rename it as SMALL_JOINER since we are not enabling big joiner yet (Anusha)
>
> Cc: Gaurav K Singh<gaurav.k.singh at intel.com>
> Cc: Jani Nikula<jani.nikula at linux.intel.com>
> Cc: Ville Syrjala<ville.syrjala at linux.intel.com>
> Cc: Anusha Srivatsa<anusha.srivatsa at intel.com>
> Cc: Dhinakaran Pandiyan<dhinakaran.pandiyan at intel.com>
> Signed-off-by: Manasi Navare<manasi.d.navare at intel.com>
> Reviewed-by: Anusha Srivatsa<anusha.srivatsa at intel.com>
> ---
> drivers/gpu/drm/i915/intel_dp.c | 104 +++++++++++++++++++++++++++++++
> drivers/gpu/drm/i915/intel_drv.h | 4 ++
> 2 files changed, 108 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 1dfcceb55182..719c2e426c28 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -45,6 +45,17 @@
>
> #define DP_DPRX_ESI_LEN 14
>
> +/* DP DSC small joiner has 2 FIFOs each of 640 x 6 bytes */
> +#define DP_DSC_MAX_SMALL_JOINER_RAM_BUFFER 61440
> +
> +/* DP DSC throughput values used for slice count calculations KPixels/s */
> +#define DP_DSC_PEAK_PIXEL_RATE 2720000
> +#define DP_DSC_MAX_ENC_THROUGHPUT_0 340000
> +#define DP_DSC_MAX_ENC_THROUGHPUT_1 400000
> +
> +/* DP DSC FEC Overhead factor = (100 - 2.4)/100 */
This comment is misleading to get the value of 976
> +#define DP_DSC_FEC_OVERHEAD_FACTOR 976
> +
> /* Compliance test status bits */
> #define INTEL_DP_RESOLUTION_SHIFT_MASK 0
> #define INTEL_DP_RESOLUTION_PREFERRED (1 << INTEL_DP_RESOLUTION_SHIFT_MASK)
> @@ -93,6 +104,14 @@ static const struct dp_link_dpll chv_dpll[] = {
> { .p1 = 4, .p2 = 1, .n = 1, .m1 = 2, .m2 = 0x6c00000 } },
> };
>
> +/* Constants for DP DSC configurations */
> +static const u8 valid_dsc_bpp[] = {6, 8, 10, 12, 15};
> +
> +/* With Single pipe configuration, HW is capable of supporting maximum
> + * of 4 slices per line.
> + */
> +static const u8 valid_dsc_slicecount[] = {1, 2, 4};
> +
> /**
> * intel_dp_is_edp - is the given port attached to an eDP panel (either CPU or PCH)
> * @intel_dp: DP struct
> @@ -4080,6 +4099,91 @@ intel_dp_get_sink_irq_esi(struct intel_dp *intel_dp, u8 *sink_irq_vector)
> DP_DPRX_ESI_LEN;
> }
>
> +uint16_t intel_dp_dsc_get_output_bpp(int link_clock, uint8_t lane_count,
> + int mode_clock, int mode_hdisplay)
Can we use u16 here. I know that for functions defined earlier in this
file, we have used uint16_t. But since we are adding new functions, we
can follow u16 or u8 accordingly.
> +{
> + u16 bits_per_pixel, max_bpp_small_joiner_ram;
> + int i;
> +
> + /*
> + * Available Link Bandwidth(Kbits/sec) = (NumberOfLanes)*
> + * (LinkSymbolClock)* 8 * ((100-FECOverhead)/100)*(TimeSlotsPerMTP)
> + * FECOverhead = 2.4%, for SST -> TimeSlotsPerMTP is 1,
> + * for MST -> TimeSlotsPerMTP has to be calculated
> + */
> + bits_per_pixel = (link_clock * lane_count * 8 *
> + DP_DSC_FEC_OVERHEAD_FACTOR) /
> + mode_clock;
> +
> + /* Small Joiner Check: output bpp <= joiner RAM (bits) / Horiz. width */
> + max_bpp_small_joiner_ram = DP_DSC_MAX_SMALL_JOINER_RAM_BUFFER /
> + mode_hdisplay;
> +
> + /*
> + * Greatest allowed DSC BPP = MIN (output BPP from avaialble Link BW
> + * check, output bpp from small joiner RAM check)
> + */
> + bits_per_pixel = min(bits_per_pixel, max_bpp_small_joiner_ram);
> +
> + /* Error out if the max bpp is less than smallest allowed valid bpp */
> + if (bits_per_pixel < valid_dsc_bpp[0]) {
> + DRM_DEBUG_KMS("Unsupported BPP %d\n", bits_per_pixel);
> + return 0;
> + }
> +
> + /* Find the nearest match in the array of known BPPs from VESA */
> + for (i = 0; i < ARRAY_SIZE(valid_dsc_bpp) - 1; i++) {
> + if (bits_per_pixel < valid_dsc_bpp[i + 1])
> + break;
> + }
> + bits_per_pixel = valid_dsc_bpp[i];
> +
> + /*
> + * Compressed BPP in U6.4 format so multiply by 16, for Gen 11,
> + * fractional part is 0
> + */
> + return bits_per_pixel << 4;
> +}
> +
> +uint8_t intel_dp_dsc_get_slice_count(struct intel_dp *intel_dp,
> + int mode_clock,
> + int mode_hdisplay)
Same comment as above.
> +{
> + u8 min_slice_count, i;
> + int max_slice_width;
> +
> + if (mode_clock <= DP_DSC_PEAK_PIXEL_RATE)
> + min_slice_count = DIV_ROUND_UP(mode_clock,
> + DP_DSC_MAX_ENC_THROUGHPUT_0);
> + else
> + min_slice_count = DIV_ROUND_UP(mode_clock,
> + DP_DSC_MAX_ENC_THROUGHPUT_1);
> +
> + max_slice_width = drm_dp_dsc_sink_max_slice_width(intel_dp->dsc_dpcd);
> + if (max_slice_width < DP_DSC_MIN_SLICE_WIDTH_VALUE) {
> + DRM_DEBUG_KMS("Unsupported slice width %d by DP DSC Sink device\n",
> + max_slice_width);
> + return 0;
> + }
> + /* Also take into account max slice width */
> + min_slice_count = min_t(uint8_t, min_slice_count,
> + DIV_ROUND_UP(mode_hdisplay,
> + max_slice_width));
> +
> + /* Find the closest match to the valid slice count values */
> + for (i = 0; i < ARRAY_SIZE(valid_dsc_slicecount); i++) {
> + if (valid_dsc_slicecount[i] >
> + drm_dp_dsc_sink_max_slice_count(intel_dp->dsc_dpcd,
> + false))
> + break;
> + if (min_slice_count <= valid_dsc_slicecount[i])
> + return valid_dsc_slicecount[i];
> + }
> +
> + DRM_DEBUG_KMS("Unsupported Slice Count %d\n", min_slice_count);
> + return 0;
> +}
> +
> static uint8_t intel_dp_autotest_link_training(struct intel_dp *intel_dp)
> {
> int status = 0;
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index 0828fcb7af90..c56e3092be25 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -1744,6 +1744,10 @@ bool intel_dp_source_supports_hbr2(struct intel_dp *intel_dp);
> bool intel_dp_source_supports_hbr3(struct intel_dp *intel_dp);
> bool
> intel_dp_get_link_status(struct intel_dp *intel_dp, uint8_t link_status[DP_LINK_STATUS_SIZE]);
> +uint16_t intel_dp_dsc_get_output_bpp(int link_clock, uint8_t lane_count,
> + int mode_clock, int mode_hdisplay);
> +uint8_t intel_dp_dsc_get_slice_count(struct intel_dp *intel_dp, int mode_clock,
> + int mode_hdisplay);
>
> static inline unsigned int intel_dp_unused_lane_mask(int lane_count)
> {
Otherwise, the patch looks good to me.
Reviewed-by: Gaurav K Singh <gaurav.k.singh at intel.com>
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