> -----Original Message-----
> From: Intel-gfx <intel-gfx-boun...@lists.freedesktop.org> On Behalf Of Imre
> Deak
> Sent: Tuesday, October 24, 2023 6:39 AM
> To: intel-gfx@lists.freedesktop.org
> Subject: [Intel-gfx] [PATCH 29/29] drm/i915: Query compressed bpp properly
> using correct DPCD and DP Spec info
>
> From: Stanislav Lisovskiy <stanislav.lisovs...@intel.com>
>
> Currently we seem to be using wrong DPCD register for reading compressed
> bpps, reading min/max input bpc instead of compressed bpp.
> Fix that, so that we now apply min/max compressed bpp limitations we get
> from DP Spec Table 2-157 DP v2.0 and/or correspondent DPCD register
> DP_DSC_MAX_BITS_PER_PIXEL_LOW/HIGH.
>
> This might also allow us to get rid of an ugly compressed bpp recalculation,
> which we had to add to make some MST hubs usable.
>
> v2: - Fix operator precedence
> v3: - Added debug info about compressed bpps
> v4: - Don't try to intersect Sink input bpp and compressed bpps.
> v5: - Decrease step while looking for suitable compressed bpp to
> accommodate.
> v6: - Use helper for getting min and max compressed_bpp (Ankit)
> v7: - Fix checkpatch warning (Ankit)
>
> Signed-off-by: Stanislav Lisovskiy <stanislav.lisovs...@intel.com>
> Signed-off-by: Ankit Nautiyal <ankit.k.nauti...@intel.com>
> ---
Reviewed-by: Arun R Murthy <arun.r.mur...@intel.com>
Thanks and Regards,
Arun R Murthy
-------------------
> drivers/gpu/drm/i915/display/intel_dp.c | 20 +++++---
> drivers/gpu/drm/i915/display/intel_dp.h | 4 ++
> drivers/gpu/drm/i915/display/intel_dp_mst.c | 54 ++++++++++-----------
> 3 files changed, 41 insertions(+), 37 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c
> b/drivers/gpu/drm/i915/display/intel_dp.c
> index 969f19484c53c..c926478621753 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -1811,7 +1811,7 @@ u16
> intel_dp_dsc_max_sink_compressed_bppx16(const struct intel_connector
> *connec
> return 0;
> }
>
> -static int dsc_sink_min_compressed_bpp(struct intel_crtc_state *pipe_config)
> +int intel_dp_dsc_sink_min_compressed_bpp(struct intel_crtc_state
> +*pipe_config)
> {
> /* From Mandatory bit rate range Support Table 2-157 (DP v2.0) */
> switch (pipe_config->output_format) {
> @@ -1828,9 +1828,9 @@ static int dsc_sink_min_compressed_bpp(struct
> intel_crtc_state *pipe_config)
> return 0;
> }
>
> -static int dsc_sink_max_compressed_bpp(const struct intel_connector
> *connector,
> - struct intel_crtc_state *pipe_config,
> - int bpc)
> +int intel_dp_dsc_sink_max_compressed_bpp(const struct intel_connector
> *connector,
> + struct intel_crtc_state *pipe_config,
> + int bpc)
> {
> return intel_dp_dsc_max_sink_compressed_bppx16(connector,
> pipe_config, bpc) >> 4;
> @@ -1944,12 +1944,14 @@ static int dsc_compute_compressed_bpp(struct
> intel_dp *intel_dp,
> int dsc_joiner_max_bpp;
>
> dsc_src_min_bpp = dsc_src_min_compressed_bpp();
> - dsc_sink_min_bpp = dsc_sink_min_compressed_bpp(pipe_config);
> + dsc_sink_min_bpp =
> intel_dp_dsc_sink_min_compressed_bpp(pipe_config);
> dsc_min_bpp = max(dsc_src_min_bpp, dsc_sink_min_bpp);
> dsc_min_bpp = max(dsc_min_bpp, to_bpp_int_roundup(limits-
> >link.min_bpp_x16));
>
> dsc_src_max_bpp = dsc_src_max_compressed_bpp(intel_dp);
> - dsc_sink_max_bpp = dsc_sink_max_compressed_bpp(connector,
> pipe_config, pipe_bpp / 3);
> + dsc_sink_max_bpp =
> intel_dp_dsc_sink_max_compressed_bpp(connector,
> + pipe_config,
> + pipe_bpp / 3);
> dsc_max_bpp = dsc_sink_max_bpp ? min(dsc_sink_max_bpp,
> dsc_src_max_bpp) : dsc_src_max_bpp;
>
> dsc_joiner_max_bpp = get_max_compressed_bpp_with_joiner(i915,
> adjusted_mode->clock, @@ -2104,12 +2106,14 @@ static int
> intel_edp_dsc_compute_pipe_bpp(struct intel_dp *intel_dp,
> pipe_config->lane_count = limits->max_lane_count;
>
> dsc_src_min_bpp = dsc_src_min_compressed_bpp();
> - dsc_sink_min_bpp = dsc_sink_min_compressed_bpp(pipe_config);
> + dsc_sink_min_bpp =
> intel_dp_dsc_sink_min_compressed_bpp(pipe_config);
> dsc_min_bpp = max(dsc_src_min_bpp, dsc_sink_min_bpp);
> dsc_min_bpp = max(dsc_min_bpp, to_bpp_int_roundup(limits-
> >link.min_bpp_x16));
>
> dsc_src_max_bpp = dsc_src_max_compressed_bpp(intel_dp);
> - dsc_sink_max_bpp = dsc_sink_max_compressed_bpp(connector,
> pipe_config, pipe_bpp / 3);
> + dsc_sink_max_bpp =
> intel_dp_dsc_sink_max_compressed_bpp(connector,
> + pipe_config,
> + pipe_bpp / 3);
> dsc_max_bpp = dsc_sink_max_bpp ? min(dsc_sink_max_bpp,
> dsc_src_max_bpp) : dsc_src_max_bpp;
> dsc_max_bpp = min(dsc_max_bpp, to_bpp_int(limits-
> >link.max_bpp_x16));
>
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.h
> b/drivers/gpu/drm/i915/display/intel_dp.h
> index 75ffab92bba41..af535b3f03ae9 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.h
> +++ b/drivers/gpu/drm/i915/display/intel_dp.h
> @@ -126,6 +126,10 @@ u16 intel_dp_dsc_get_max_compressed_bpp(struct
> drm_i915_private *i915,
> enum intel_output_format
> output_format,
> u32 pipe_bpp,
> u32 timeslots);
> +int intel_dp_dsc_sink_min_compressed_bpp(struct intel_crtc_state
> +*pipe_config); int intel_dp_dsc_sink_max_compressed_bpp(const struct
> intel_connector *connector,
> + struct intel_crtc_state *pipe_config,
> + int bpc);
> u8 intel_dp_dsc_get_slice_count(const struct intel_connector *connector,
> int mode_clock, int mode_hdisplay,
> bool bigjoiner);
> diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> index d6c52906ac6c3..457ace825d931 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> @@ -157,6 +157,9 @@ static int intel_dp_mst_find_vcpi_slots_for_bpp(struct
> intel_encoder *encoder,
> crtc_state->port_clock,
> crtc_state->lane_count);
>
> + drm_dbg_kms(&i915->drm, "Looking for slots in range min bpp %d max
> bpp %d\n",
> + min_bpp, max_bpp);
> +
> for (bpp = max_bpp; bpp >= min_bpp; bpp -= step) {
> struct intel_link_m_n remote_m_n;
> int link_bpp;
> @@ -246,8 +249,7 @@ static int intel_dp_dsc_mst_compute_link_config(struct
> intel_encoder *encoder,
> u8 dsc_bpc[3] = {};
> int min_bpp, max_bpp, sink_min_bpp, sink_max_bpp;
> u8 dsc_max_bpc;
> - bool need_timeslot_recalc = false;
> - u32 last_compressed_bpp;
> + int min_compressed_bpp, max_compressed_bpp;
>
> /* Max DSC Input BPC for ICL is 10 and for TGL+ is 12 */
> if (DISPLAY_VER(i915) >= 12)
> @@ -283,38 +285,32 @@ static int
> intel_dp_dsc_mst_compute_link_config(struct intel_encoder *encoder,
> if (max_bpp > sink_max_bpp)
> max_bpp = sink_max_bpp;
>
> - min_bpp = max(min_bpp, to_bpp_int_roundup(limits-
> >link.min_bpp_x16));
> - max_bpp = min(max_bpp, to_bpp_int(limits->link.max_bpp_x16));
> + max_compressed_bpp =
> intel_dp_dsc_sink_max_compressed_bpp(connector,
> + crtc_state,
> + max_bpp /
> 3);
> + max_compressed_bpp = min(max_compressed_bpp,
> + to_bpp_int(limits->link.max_bpp_x16));
>
> - slots = intel_dp_mst_find_vcpi_slots_for_bpp(encoder, crtc_state,
> max_bpp,
> - min_bpp, limits,
> - conn_state, 2 * 3, true);
> + min_compressed_bpp =
> intel_dp_dsc_sink_min_compressed_bpp(crtc_state);
> + min_compressed_bpp = max(min_compressed_bpp,
> + to_bpp_int_roundup(limits-
> >link.min_bpp_x16));
> +
> + drm_dbg_kms(&i915->drm, "DSC Sink supported compressed min bpp
> %d compressed max bpp %d\n",
> + min_compressed_bpp, max_compressed_bpp);
> +
> + /* Align compressed bpps according to our own constraints */
> + max_compressed_bpp = intel_dp_dsc_nearest_valid_bpp(i915,
> max_compressed_bpp,
> + crtc_state-
> >pipe_bpp);
> + min_compressed_bpp = intel_dp_dsc_nearest_valid_bpp(i915,
> min_compressed_bpp,
> + crtc_state-
> >pipe_bpp);
> +
> + slots = intel_dp_mst_find_vcpi_slots_for_bpp(encoder, crtc_state,
> max_compressed_bpp,
> + min_compressed_bpp,
> limits,
> + conn_state, 1, true);
>
> if (slots < 0)
> return slots;
>
> - last_compressed_bpp = crtc_state->dsc.compressed_bpp;
> -
> - crtc_state->dsc.compressed_bpp =
> intel_dp_dsc_nearest_valid_bpp(i915,
> -
> last_compressed_bpp,
> -
> crtc_state->pipe_bpp);
> -
> - if (crtc_state->dsc.compressed_bpp != last_compressed_bpp)
> - need_timeslot_recalc = true;
> -
> - /*
> - * Apparently some MST hubs dislike if vcpi slots are not matching
> precisely
> - * the actual compressed bpp we use.
> - */
> - if (need_timeslot_recalc) {
> - slots = intel_dp_mst_find_vcpi_slots_for_bpp(encoder,
> crtc_state,
> - crtc_state-
> >dsc.compressed_bpp,
> - crtc_state-
> >dsc.compressed_bpp,
> - limits, conn_state,
> 2 * 3, true);
> - if (slots < 0)
> - return slots;
> - }
> -
> return 0;
> }
> static int intel_dp_mst_update_slots(struct intel_encoder *encoder,
> --
> 2.39.2
