[PATCH 12/13] drm/i915/dp: Get optimal link config to have best compressed bpp
Lisovskiy, Stanislav
stanislav.lisovskiy at intel.com
Tue May 16 10:43:44 UTC 2023
On Fri, May 12, 2023 at 11:54:16AM +0530, Ankit Nautiyal wrote:
> Currently, we take the max lane, rate and pipe bpp, to get the maximum
> compressed bpp possible. We then set the output bpp to this value.
> This patch provides support to have max bpp, min rate and min lanes,
> that can support the min compressed bpp.
>
> v2:
> -Avoid ending up with compressed bpp, same as pipe bpp. (Stan)
> -Fix the checks for limits->max/min_bpp while iterating over list of
> valid DSC bpcs. (Stan)
>
> v3:
> -Refactor the code to have pipe bpp/compressed bpp computation and slice
> count calculation separately for different cases.
>
> v4:
> -Separate the pipe_bpp calculation for eDP and DP.
>
> Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal at intel.com>
> ---
> drivers/gpu/drm/i915/display/intel_dp.c | 305 +++++++++++++++++++-----
> 1 file changed, 245 insertions(+), 60 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index 39e2bf3d738d..578320220c9a 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -1642,6 +1642,209 @@ static bool intel_dp_dsc_supports_format(struct intel_dp *intel_dp,
> return drm_dp_dsc_sink_supports_format(intel_dp->dsc_dpcd, sink_dsc_format);
> }
>
> +static bool is_dsc_bw_sufficient(int link_rate, int lane_count, int compressed_bpp,
> + const struct drm_display_mode *adjusted_mode)
> +{
> + int mode_rate = intel_dp_link_required(adjusted_mode->crtc_clock, compressed_bpp);
> + int link_avail = intel_dp_max_data_rate(link_rate, lane_count);
> +
> + return mode_rate <= link_avail;
> +}
> +
> +static int dsc_compute_link_config(struct intel_dp *intel_dp,
> + struct intel_crtc_state *pipe_config,
> + struct link_config_limits *limits,
> + int pipe_bpp,
> + u16 compressed_bpp,
> + int timeslots)
> +{
> + const struct drm_display_mode *adjusted_mode =
> + &pipe_config->hw.adjusted_mode;
> + int link_rate, lane_count;
> + int dsc_max_bpp;
> + struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
> + int i;
> +
> + for (i = 0; i < intel_dp->num_common_rates; i++) {
> + link_rate = intel_dp_common_rate(intel_dp, i);
> + if (link_rate < limits->min_rate || link_rate > limits->max_rate)
> + continue;
> +
> + for (lane_count = limits->min_lane_count;
> + lane_count <= limits->max_lane_count;
> + lane_count <<= 1) {
> + dsc_max_bpp = intel_dp_dsc_get_max_compressed_bpp(dev_priv,
> + link_rate,
> + lane_count,
> + adjusted_mode->crtc_clock,
> + adjusted_mode->crtc_hdisplay,
> + pipe_config->bigjoiner_pipes,
> + pipe_config->output_format,
> + pipe_bpp, timeslots);
> + /*
> + * According to DSC 1.2a Section 4.1.1 Table 4.1 the maximum
> + * supported PPS value can be 63.9375 and with the further
> + * mention that bpp should be programmed double the target bpp
> + * restricting our target bpp to be 31.9375 at max
> + */
> + if (pipe_config->output_format == INTEL_OUTPUT_FORMAT_YCBCR420)
> + dsc_max_bpp = min_t(u16, dsc_max_bpp, 31);
> +
> + if (compressed_bpp > dsc_max_bpp)
> + continue;
> +
> + if (!is_dsc_bw_sufficient(link_rate, lane_count,
> + compressed_bpp, adjusted_mode))
> + continue;
> +
> + pipe_config->lane_count = lane_count;
> + pipe_config->port_clock = link_rate;
> +
> + return 0;
> + }
> + }
> +
> + return -EINVAL;
> +}
> +
> +static
> +u16 intel_dp_dsc_max_sink_compressed_bppx16(struct intel_dp *intel_dp,
> + struct intel_crtc_state *pipe_config,
> + int bpc)
> +{
> + u16 max_bppx16 = drm_edp_dsc_sink_output_bpp(intel_dp->dsc_dpcd);
> +
> + if (max_bppx16)
> + return max_bppx16;
> + /*
> + * If support not given in DPCD 67h, 68h use the Maximum Allowed bit rate
> + * values as given in spec Table 2-157 DP v2.0
> + */
> + switch (pipe_config->output_format) {
> + case INTEL_OUTPUT_FORMAT_RGB:
> + case INTEL_OUTPUT_FORMAT_YCBCR444:
> + return (3 * bpc) << 4;
> + case INTEL_OUTPUT_FORMAT_YCBCR420:
> + return (3 * (bpc / 2)) << 4;
> + default:
> + MISSING_CASE(pipe_config->output_format);
> + break;
> + }
> +
> + return 0;
> +}
> +
> +static u16 intel_dp_dsc_min_compressed_bppx16(struct intel_crtc_state *pipe_config)
> +{
> + switch (pipe_config->output_format) {
> + case INTEL_OUTPUT_FORMAT_RGB:
> + case INTEL_OUTPUT_FORMAT_YCBCR444:
> + return 8 << 4;
> + case INTEL_OUTPUT_FORMAT_YCBCR420:
> + return 6 << 4;
> + default:
> + MISSING_CASE(pipe_config->output_format);
> + break;
> + }
> +
> + return 0;
> +}
> +
> +static int dsc_compute_compressed_bpp(struct intel_dp *intel_dp,
> + struct intel_crtc_state *pipe_config,
> + struct link_config_limits *limits,
> + int pipe_bpp,
> + int timeslots)
> +{
> + struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
> + u16 compressed_bpp;
> + int dsc_min_bpp, dsc_src_max_bpp, dsc_sink_max_bpp, dsc_max_bpp;
> + int ret;
> +
> + dsc_min_bpp = max(intel_dp_dsc_min_compressed_bppx16(pipe_config) >> 4, 8);
> + if (DISPLAY_VER(dev_priv) <= 12)
> + dsc_src_max_bpp = 23;
> + else
> + dsc_src_max_bpp = 27;
I would may be added some comment about what are those "23/27" numbers or
may be even created some self-explanatory #define constants for those.
Otherwise in a couple of years, even we ourselves might not be able to recall
immediately where those numbers are taken from.
Otherwise looks good to me,
Reviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy at intel.com>
> + dsc_sink_max_bpp =
> + intel_dp_dsc_max_sink_compressed_bppx16(intel_dp,
> + pipe_config, pipe_bpp / 3) >> 4;
> +
> + dsc_max_bpp = dsc_sink_max_bpp ? min(dsc_sink_max_bpp, dsc_src_max_bpp) : dsc_src_max_bpp;
> +
> + /* Compressed BPP should be less than the Input DSC bpp */
> + dsc_max_bpp = min(dsc_max_bpp, pipe_bpp - 1);
> +
> + for (compressed_bpp = dsc_max_bpp;
> + compressed_bpp >= dsc_min_bpp;
> + compressed_bpp--) {
> + ret = dsc_compute_link_config(intel_dp,
> + pipe_config,
> + limits,
> + pipe_bpp,
> + compressed_bpp,
> + timeslots);
> + if (ret == 0) {
> + pipe_config->dsc.compressed_bpp = compressed_bpp;
> + return 0;
> + }
> + }
> +
> + return -EINVAL;
> +}
> +
> +static int intel_dp_dsc_compute_pipe_bpp(struct intel_dp *intel_dp,
> + struct intel_crtc_state *pipe_config,
> + struct drm_connector_state *conn_state,
> + struct link_config_limits *limits,
> + int timeslots)
> +{
> + struct drm_i915_private *i915 = dp_to_i915(intel_dp);
> + u8 dsc_bpc[3] = {0};
> + u8 dsc_max_bpc, dsc_max_bpp;
> + u8 dsc_min_bpc, dsc_min_bpp;
> + u8 max_req_bpc = conn_state->max_requested_bpc;
> + int i, bpp, ret;
> + int num_bpc = drm_dp_dsc_sink_supported_input_bpcs(intel_dp->dsc_dpcd,
> + dsc_bpc);
> +
> + /* Max DSC Input BPC for ICL is 10 and for TGL+ is 12 */
> + if (DISPLAY_VER(i915) >= 12)
> + dsc_max_bpc = min_t(u8, 12, max_req_bpc);
> + else
> + dsc_max_bpc = min_t(u8, 10, max_req_bpc);
> +
> + dsc_max_bpp = min(dsc_max_bpc * 3, limits->max_bpp);
> +
> + /* Min DSC Input BPC for ICL+ is 8 */
> + dsc_min_bpc = 8;
> + dsc_min_bpp = max(dsc_min_bpc * 3, limits->min_bpp);
> +
> + /*
> + * Get the maximum DSC bpc that will be supported by any valid
> + * link configuration and compressed bpp.
> + */
> + for (i = 0; i < num_bpc; i++) {
> + bpp = dsc_bpc[i] * 3;
> +
> + if (bpp < dsc_min_bpp)
> + break;
> +
> + if (bpp > dsc_max_bpp)
> + continue;
> +
> + ret = dsc_compute_compressed_bpp(intel_dp, pipe_config,
> + limits, bpp, timeslots);
> + if (ret == 0) {
> + pipe_config->pipe_bpp = bpp;
> +
> + return 0;
> + }
> + }
> +
> + return -EINVAL;
> +}
> +
> static
> bool is_dsc_pipe_bpp_sufficient(int pipe_bpp)
> {
> @@ -1649,6 +1852,31 @@ bool is_dsc_pipe_bpp_sufficient(int pipe_bpp)
> return (pipe_bpp < 8 * 3);
> }
>
> +static int intel_edp_dsc_compute_pipe_bpp(struct intel_dp *intel_dp,
> + struct intel_crtc_state *pipe_config,
> + struct drm_connector_state *conn_state,
> + struct link_config_limits *limits)
> +{
> + /* For eDP use max bpp that can be supported with DSC. */
> + int pipe_bpp = intel_dp_dsc_compute_max_bpp(intel_dp,
> + conn_state->max_requested_bpc);
> + struct drm_i915_private *i915 = dp_to_i915(intel_dp);
> +
> + if (!is_dsc_pipe_bpp_sufficient(pipe_bpp)) {
> + drm_dbg_kms(&i915->drm,
> + "No DSC support for less than 8bpc\n");
> + return -EINVAL;
> + }
> + pipe_config->pipe_bpp = pipe_bpp;
> + pipe_config->port_clock = limits->max_rate;
> + pipe_config->lane_count = limits->max_lane_count;
> + pipe_config->dsc.compressed_bpp =
> + min_t(u16, drm_edp_dsc_sink_output_bpp(intel_dp->dsc_dpcd) >> 4,
> + pipe_config->pipe_bpp);
> +
> + return 0;
> +}
> +
> int intel_dp_dsc_compute_config(struct intel_dp *intel_dp,
> struct intel_crtc_state *pipe_config,
> struct drm_connector_state *conn_state,
> @@ -1671,6 +1899,12 @@ int intel_dp_dsc_compute_config(struct intel_dp *intel_dp,
> if (!intel_dp_dsc_supports_format(intel_dp, pipe_config->output_format))
> return -EINVAL;
>
> + /*
> + * compute pipe bpp is set to false for DP MST DSC case
> + * and compressed_bpp is calculated same time once
> + * vpci timeslots are allocated, because overall bpp
> + * calculation procedure is bit different for MST case.
> + */
> if (compute_pipe_bpp) {
> int pipe_bpp;
> int forced_bpp = intel_dp->force_dsc_bpc * 3;
> @@ -1683,31 +1917,25 @@ int intel_dp_dsc_compute_config(struct intel_dp *intel_dp,
> forced_bpp && !is_dsc_pipe_bpp_sufficient(forced_bpp),
> "Cannot force dsc bpc:%d, due to dsc bpc limits\n",
> intel_dp->force_dsc_bpc);
> -
> - pipe_bpp = intel_dp_dsc_compute_max_bpp(intel_dp,
> - conn_state->max_requested_bpc);
> -
> - if (!is_dsc_pipe_bpp_sufficient(pipe_bpp)) {
> - drm_dbg_kms(&dev_priv->drm, "No DSC support for less than 8bpc\n");
> - return -EINVAL;
> + if (intel_dp_is_edp(intel_dp))
> + ret = intel_edp_dsc_compute_pipe_bpp(intel_dp, pipe_config,
> + conn_state, limits);
> + else
> + ret = intel_dp_dsc_compute_pipe_bpp(intel_dp, pipe_config,
> + conn_state, limits, timeslots);
> + if (ret) {
> + drm_dbg_kms(&dev_priv->drm,
> + "No Valid pipe bpp for given mode ret = %d\n", ret);
> + return ret;
> }
> }
> -
> - pipe_config->pipe_bpp = pipe_bpp;
> }
>
> - /*
> - * For now enable DSC for max link rate, max lane count.
> - * Optimize this later for the minimum possible link rate/lane count
> - * with DSC enabled for the requested mode.
> - */
> pipe_config->port_clock = limits->max_rate;
> pipe_config->lane_count = limits->max_lane_count;
>
> + /* Calculate Slice count */
> if (intel_dp_is_edp(intel_dp)) {
> - pipe_config->dsc.compressed_bpp =
> - min_t(u16, drm_edp_dsc_sink_output_bpp(intel_dp->dsc_dpcd) >> 4,
> - pipe_config->pipe_bpp);
> pipe_config->dsc.slice_count =
> drm_dp_dsc_sink_max_slice_count(intel_dp->dsc_dpcd,
> true);
> @@ -1717,37 +1945,8 @@ int intel_dp_dsc_compute_config(struct intel_dp *intel_dp,
> return -EINVAL;
> }
> } else {
> - u16 dsc_max_compressed_bpp = 0;
> u8 dsc_dp_slice_count;
>
> - if (compute_pipe_bpp) {
> - dsc_max_compressed_bpp =
> - intel_dp_dsc_get_max_compressed_bpp(dev_priv,
> - pipe_config->port_clock,
> - pipe_config->lane_count,
> - adjusted_mode->crtc_clock,
> - adjusted_mode->crtc_hdisplay,
> - pipe_config->bigjoiner_pipes,
> - pipe_config->output_format,
> - pipe_config->pipe_bpp,
> - timeslots);
> - /*
> - * According to DSC 1.2a Section 4.1.1 Table 4.1 the maximum
> - * supported PPS value can be 63.9375 and with the further
> - * mention that bpp should be programmed double the target bpp
> - * restricting our target bpp to be 31.9375 at max
> - */
> - if (pipe_config->output_format == INTEL_OUTPUT_FORMAT_YCBCR420)
> - dsc_max_compressed_bpp = min_t(u16,
> - dsc_max_compressed_bpp,
> - 31);
> -
> - if (!dsc_max_compressed_bpp) {
> - drm_dbg_kms(&dev_priv->drm,
> - "Compressed BPP not supported\n");
> - return -EINVAL;
> - }
> - }
> dsc_dp_slice_count =
> intel_dp_dsc_get_slice_count(intel_dp,
> adjusted_mode->crtc_clock,
> @@ -1759,20 +1958,6 @@ int intel_dp_dsc_compute_config(struct intel_dp *intel_dp,
> return -EINVAL;
> }
>
> - /*
> - * compute pipe bpp is set to false for DP MST DSC case
> - * and compressed_bpp is calculated same time once
> - * vpci timeslots are allocated, because overall bpp
> - * calculation procedure is bit different for MST case.
> - */
> - if (compute_pipe_bpp) {
> - u16 output_bpp = intel_dp_output_bpp(pipe_config->output_format,
> - pipe_config->pipe_bpp);
> -
> - pipe_config->dsc.compressed_bpp = min_t(u16,
> - dsc_max_compressed_bpp,
> - output_bpp);
> - }
> pipe_config->dsc.slice_count = dsc_dp_slice_count;
> }
> /*
> --
> 2.25.1
>
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