On Tue, May 16, 2023 at 01:43:44PM +0300, Lisovskiy, Stanislav wrote:
> 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@xxxxxxxxx>
> > ---
> > 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.
I dislike defines like that. They are single use so don't actually
do anything in terms of avoiding typoes and other accidental
mismatches, and people always seem put them in some random place
(eg. top of file) so then it takes extra work to find them.
The best approach IMO is to just use functions with good names.
Eg. in this case we could just have a full set of clear functions:
dsc_{sink,source}_{min,max}_bpp() or something along those line.
> 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@xxxxxxxxx>
>
> > + 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
> >
--
Ville Syrjälä
Intel
