[PATCH 05/26] drm/i915/dp: Add helpers for Compressed BPP and Slice Count for DSC
Manasi Navare
manasi.d.navare at intel.com
Thu Sep 13 21:55:48 UTC 2018
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 */
+#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)
+{
+ 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)
+{
+ 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)
{
--
2.18.0
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