Add helpers to query the DP DSC sink device's per-slice throughput as well as a DSC branch device's overall throughput and line-width capabilities.
v2 (Ville): - Rename pixel_clock to peak_pixel_rate, document what the value means in case of MST tiled displays. - Fix name of drm_dp_dsc_branch_max_slice_throughput() to drm_dp_dsc_sink_max_slice_throughput(). v3: - Fix the DSC branch device minimum valid line width value from 2560 to 5120 pixels. - Fix drm_dp_dsc_sink_max_slice_throughput()'s pixel_clock parameter name to peak_pixel_rate in header file. - Add handling for throughput mode 0 granular delta, defined by DP Standard v2.1a. Cc: [email protected] Suggested-by: Ville Syrjälä <[email protected]> Signed-off-by: Imre Deak <[email protected]> --- drivers/gpu/drm/display/drm_dp_helper.c | 156 ++++++++++++++++++++++++ include/drm/display/drm_dp.h | 3 + include/drm/display/drm_dp_helper.h | 5 + 3 files changed, 164 insertions(+) diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c index 1c74fe9459ad9..6084ca7fbe263 100644 --- a/drivers/gpu/drm/display/drm_dp_helper.c +++ b/drivers/gpu/drm/display/drm_dp_helper.c @@ -2844,6 +2844,162 @@ int drm_dp_dsc_sink_supported_input_bpcs(const u8 dsc_dpcd[DP_DSC_RECEIVER_CAP_S } EXPORT_SYMBOL(drm_dp_dsc_sink_supported_input_bpcs); +/* + * See DP Standard v2.1a 2.8.4 Minimum Slices/Display, Table 2-159 and + * Appendix L.1 Derivation of Slice Count Requirements. + */ +static int dsc_sink_min_slice_throughput(int peak_pixel_rate) +{ + if (peak_pixel_rate >= 4800000) + return 600000; + else if (peak_pixel_rate >= 2700000) + return 400000; + else + return 340000; +} + +/** + * drm_dp_dsc_sink_max_slice_throughput() - Get a DSC sink's maximum pixel throughput per slice + * @dsc_dpcd: DSC sink's capabilities from DPCD + * @peak_pixel_rate: Cumulative peak pixel rate in kHz + * @is_rgb_yuv444: The mode is either RGB or YUV444 + * + * Return the DSC sink device's maximum pixel throughput per slice, based on + * the device's @dsc_dpcd capabilities, the @peak_pixel_rate of the transferred + * stream(s) and whether the output format @is_rgb_yuv444 or yuv422/yuv420. + * + * Note that @peak_pixel_rate is the total pixel rate transferred to the same + * DSC/display sink. For instance to calculate a tile's slice count of an MST + * multi-tiled display sink (not considering here the required + * rounding/alignment of slice count):: + * + * @peak_pixel_rate = tile_pixel_rate * tile_count + * total_slice_count = @peak_pixel_rate / drm_dp_dsc_sink_max_slice_throughput(@peak_pixel_rate) + * tile_slice_count = total_slice_count / tile_count + * + * Returns: + * The maximum pixel throughput per slice supported by the DSC sink device + * in kPixels/sec. + */ +int drm_dp_dsc_sink_max_slice_throughput(const u8 dsc_dpcd[DP_DSC_RECEIVER_CAP_SIZE], + int peak_pixel_rate, bool is_rgb_yuv444) +{ + int throughput; + int delta = 0; + int base; + + throughput = dsc_dpcd[DP_DSC_PEAK_THROUGHPUT - DP_DSC_SUPPORT]; + + if (is_rgb_yuv444) { + throughput = (throughput & DP_DSC_THROUGHPUT_MODE_0_MASK) >> + DP_DSC_THROUGHPUT_MODE_0_SHIFT; + + delta = ((dsc_dpcd[DP_DSC_RC_BUF_BLK_SIZE - DP_DSC_SUPPORT]) & + DP_DSC_THROUGHPUT_MODE_0_DELTA_MASK) >> + DP_DSC_THROUGHPUT_MODE_0_DELTA_SHIFT; /* in units of 2 MPixels/sec */ + delta *= 2000; + } else { + throughput = (throughput & DP_DSC_THROUGHPUT_MODE_1_MASK) >> + DP_DSC_THROUGHPUT_MODE_1_SHIFT; + } + + switch (throughput) { + case 0: + return dsc_sink_min_slice_throughput(peak_pixel_rate); + case 1: + base = 340000; + break; + case 2 ... 14: + base = 400000 + 50000 * (throughput - 2); + break; + case 15: + base = 170000; + break; + default: + WARN(1, "Missing case %d\n", throughput); + base = 340000; + break; + } + + return base + delta; +} +EXPORT_SYMBOL(drm_dp_dsc_sink_max_slice_throughput); + +static u8 dsc_branch_dpcd_cap(const u8 dpcd[DP_DSC_BRANCH_CAP_SIZE], int reg) +{ + return dpcd[reg - DP_DSC_BRANCH_OVERALL_THROUGHPUT_0]; +} + +/** + * drm_dp_dsc_branch_max_overall_throughput() - Branch device's max overall DSC pixel throughput + * @dsc_branch_dpcd: DSC branch capabilities from DPCD + * @is_rgb_yuv444: The mode is either RGB or YUV444 + * + * Return the branch device's maximum overall DSC pixel throughput, based on + * the device's DPCD DSC branch capabilities, and whether the output + * format @is_rgb_yuv444 or yuv422/yuv420. + * + * Returns: + * - 0: The maximum overall throughput capability is not indicated by + * the device separately and it must be determined from the per-slice + * max throughput (see @drm_dp_dsc_branch_slice_max_throughput()) + * and the maximum slice count supported by the device. + * - > 0: The maximum overall DSC pixel throughput supported by the branch + * device in kPixels/sec. + */ +int drm_dp_dsc_branch_max_overall_throughput(const u8 dsc_branch_dpcd[DP_DSC_BRANCH_CAP_SIZE], + bool is_rgb_yuv444) +{ + int throughput; + + if (is_rgb_yuv444) + throughput = dsc_branch_dpcd_cap(dsc_branch_dpcd, + DP_DSC_BRANCH_OVERALL_THROUGHPUT_0); + else + throughput = dsc_branch_dpcd_cap(dsc_branch_dpcd, + DP_DSC_BRANCH_OVERALL_THROUGHPUT_1); + + switch (throughput) { + case 0: + return 0; + case 1: + return 680000; + default: + return 600000 + 50000 * throughput; + } +} +EXPORT_SYMBOL(drm_dp_dsc_branch_max_overall_throughput); + +/** + * drm_dp_dsc_branch_max_line_width() - Branch device's max DSC line width + * @dsc_branch_dpcd: DSC branch capabilities from DPCD + * + * Return the branch device's maximum overall DSC line width, based on + * the device's @dsc_branch_dpcd capabilities. + * + * Returns: + * - 0: The maximum line width is not indicated by the device + * separately and it must be determined from the maximum + * slice count and slice-width supported by the device. + * - %-EINVAL: The device indicates an invalid maximum line width + * (< 5120 pixels). + * - >= 5120: The maximum line width in pixels. + */ +int drm_dp_dsc_branch_max_line_width(const u8 dsc_branch_dpcd[DP_DSC_BRANCH_CAP_SIZE]) +{ + int line_width = dsc_branch_dpcd_cap(dsc_branch_dpcd, DP_DSC_BRANCH_MAX_LINE_WIDTH); + + switch (line_width) { + case 0: + return 0; + case 1 ... 15: + return -EINVAL; + default: + return line_width * 320; + } +} +EXPORT_SYMBOL(drm_dp_dsc_branch_max_line_width); + static int drm_dp_read_lttpr_regs(struct drm_dp_aux *aux, const u8 dpcd[DP_RECEIVER_CAP_SIZE], int address, u8 *buf, int buf_size) diff --git a/include/drm/display/drm_dp.h b/include/drm/display/drm_dp.h index cf318e3ddb5c5..e4eebabab9759 100644 --- a/include/drm/display/drm_dp.h +++ b/include/drm/display/drm_dp.h @@ -258,6 +258,8 @@ # define DP_DSC_RC_BUF_BLK_SIZE_4 0x1 # define DP_DSC_RC_BUF_BLK_SIZE_16 0x2 # define DP_DSC_RC_BUF_BLK_SIZE_64 0x3 +# define DP_DSC_THROUGHPUT_MODE_0_DELTA_SHIFT 3 /* DP 2.1a, in units of 2 MPixels/sec */ +# define DP_DSC_THROUGHPUT_MODE_0_DELTA_MASK (0x1f << DP_DSC_THROUGHPUT_MODE_0_DELTA_SHIFT) #define DP_DSC_RC_BUF_SIZE 0x063 @@ -1686,6 +1688,7 @@ enum drm_dp_phy { #define DP_BRANCH_OUI_HEADER_SIZE 0xc #define DP_RECEIVER_CAP_SIZE 0xf #define DP_DSC_RECEIVER_CAP_SIZE 0x10 /* DSC Capabilities 0x60 through 0x6F */ +#define DP_DSC_BRANCH_CAP_SIZE 3 #define EDP_PSR_RECEIVER_CAP_SIZE 2 #define EDP_DISPLAY_CTL_CAP_SIZE 5 #define DP_LTTPR_COMMON_CAP_SIZE 8 diff --git a/include/drm/display/drm_dp_helper.h b/include/drm/display/drm_dp_helper.h index e438c44409952..df2f24b950e4c 100644 --- a/include/drm/display/drm_dp_helper.h +++ b/include/drm/display/drm_dp_helper.h @@ -211,6 +211,11 @@ u8 drm_dp_dsc_sink_max_slice_count(const u8 dsc_dpcd[DP_DSC_RECEIVER_CAP_SIZE], u8 drm_dp_dsc_sink_line_buf_depth(const u8 dsc_dpcd[DP_DSC_RECEIVER_CAP_SIZE]); int drm_dp_dsc_sink_supported_input_bpcs(const u8 dsc_dpc[DP_DSC_RECEIVER_CAP_SIZE], u8 dsc_bpc[3]); +int drm_dp_dsc_sink_max_slice_throughput(const u8 dsc_dpcd[DP_DSC_RECEIVER_CAP_SIZE], + int peak_pixel_rate, bool is_rgb_yuv444); +int drm_dp_dsc_branch_max_overall_throughput(const u8 dsc_branch_dpcd[DP_DSC_BRANCH_CAP_SIZE], + bool is_rgb_yuv444); +int drm_dp_dsc_branch_max_line_width(const u8 dsc_branch_dpcd[DP_DSC_BRANCH_CAP_SIZE]); static inline bool drm_dp_sink_supports_dsc(const u8 dsc_dpcd[DP_DSC_RECEIVER_CAP_SIZE]) -- 2.49.1
