> Subject: [PATCH 2/8] drm/i915/display: Store compressed bpp in U6.4 format
>
> From: Ankit Nautiyal <ankit.k.nautiyal@xxxxxxxxx>
>
> DSC parameter bits_per_pixel is stored in U6.4 format.
> The 4 bits represent the fractional part of the bpp.
> Currently we use compressed_bpp member of dsc structure to store only the
> integral part of the bits_per_pixel.
> To store the full bits_per_pixel along with the fractional part, compressed_bpp
> is changed to store bpp in U6.4 formats. Intergral part is retrieved by simply
> right shifting the member compressed_bpp by 4.
>
> v2:
> -Use to_bpp_int, to_bpp_frac_dec, to_bpp_x16 helpers while dealing with
> compressed bpp. (Suraj) -Fix comment styling. (Suraj)
>
> Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/display/icl_dsi.c | 10 ++++----
> drivers/gpu/drm/i915/display/intel_audio.c | 2 +-
> drivers/gpu/drm/i915/display/intel_bios.c | 4 +--
> drivers/gpu/drm/i915/display/intel_cdclk.c | 2 +-
> drivers/gpu/drm/i915/display/intel_display.c | 2 +-
> .../drm/i915/display/intel_display_types.h | 18 ++++++++++++-
> drivers/gpu/drm/i915/display/intel_dp.c | 25 +++++++++++--------
> drivers/gpu/drm/i915/display/intel_dp_mst.c | 18 ++++++-------
> drivers/gpu/drm/i915/display/intel_vdsc.c | 4 +--
> 9 files changed, 52 insertions(+), 33 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/icl_dsi.c
> b/drivers/gpu/drm/i915/display/icl_dsi.c
> index ad6488e9c2b2..df98f35bbcda 100644
> --- a/drivers/gpu/drm/i915/display/icl_dsi.c
> +++ b/drivers/gpu/drm/i915/display/icl_dsi.c
> @@ -330,7 +330,7 @@ static int afe_clk(struct intel_encoder *encoder,
> int bpp;
>
> if (crtc_state->dsc.compression_enable)
> - bpp = crtc_state->dsc.compressed_bpp;
> + bpp = to_bpp_int(crtc_state->dsc.compressed_bpp_x16);
> else
> bpp = mipi_dsi_pixel_format_to_bpp(intel_dsi->pixel_format);
>
> @@ -860,7 +860,7 @@ gen11_dsi_set_transcoder_timings(struct
> intel_encoder *encoder,
> * compressed and non-compressed bpp.
> */
> if (crtc_state->dsc.compression_enable) {
> - mul = crtc_state->dsc.compressed_bpp;
> + mul = to_bpp_int(crtc_state->dsc.compressed_bpp_x16);
> div = mipi_dsi_pixel_format_to_bpp(intel_dsi->pixel_format);
> }
>
> @@ -884,7 +884,7 @@ gen11_dsi_set_transcoder_timings(struct
> intel_encoder *encoder,
> int bpp, line_time_us, byte_clk_period_ns;
>
> if (crtc_state->dsc.compression_enable)
> - bpp = crtc_state->dsc.compressed_bpp;
> + bpp = to_bpp_int(crtc_state-
> >dsc.compressed_bpp_x16);
> else
> bpp = mipi_dsi_pixel_format_to_bpp(intel_dsi-
> >pixel_format);
>
> @@ -1451,8 +1451,8 @@ static void gen11_dsi_get_timings(struct
> intel_encoder *encoder,
> struct drm_display_mode *adjusted_mode =
> &pipe_config->hw.adjusted_mode;
>
> - if (pipe_config->dsc.compressed_bpp) {
> - int div = pipe_config->dsc.compressed_bpp;
> + if (pipe_config->dsc.compressed_bpp_x16) {
> + int div = to_bpp_int(pipe_config->dsc.compressed_bpp_x16);
> int mul = mipi_dsi_pixel_format_to_bpp(intel_dsi-
> >pixel_format);
>
> adjusted_mode->crtc_htotal =
> diff --git a/drivers/gpu/drm/i915/display/intel_audio.c
> b/drivers/gpu/drm/i915/display/intel_audio.c
> index 19605264a35c..aa93ccd6c2aa 100644
> --- a/drivers/gpu/drm/i915/display/intel_audio.c
> +++ b/drivers/gpu/drm/i915/display/intel_audio.c
> @@ -528,7 +528,7 @@ static unsigned int calc_hblank_early_prog(struct
> intel_encoder *encoder,
> h_active = crtc_state->hw.adjusted_mode.crtc_hdisplay;
> h_total = crtc_state->hw.adjusted_mode.crtc_htotal;
> pixel_clk = crtc_state->hw.adjusted_mode.crtc_clock;
> - vdsc_bpp = crtc_state->dsc.compressed_bpp;
> + vdsc_bpp = to_bpp_int(crtc_state->dsc.compressed_bpp_x16);
> cdclk = i915->display.cdclk.hw.cdclk;
> /* fec= 0.972261, using rounding multiplier of 1000000 */
> fec_coeff = 972261;
> diff --git a/drivers/gpu/drm/i915/display/intel_bios.c
> b/drivers/gpu/drm/i915/display/intel_bios.c
> index 858c959f7bab..7b6d299fbcf2 100644
> --- a/drivers/gpu/drm/i915/display/intel_bios.c
> +++ b/drivers/gpu/drm/i915/display/intel_bios.c
> @@ -3384,8 +3384,8 @@ static void fill_dsc(struct intel_crtc_state *crtc_state,
>
> crtc_state->pipe_bpp = bpc * 3;
>
> - crtc_state->dsc.compressed_bpp = min(crtc_state->pipe_bpp,
> - VBT_DSC_MAX_BPP(dsc-
> >max_bpp));
> + crtc_state->dsc.compressed_bpp_x16 = to_bpp_x16(min(crtc_state-
> >pipe_bpp,
> +
> VBT_DSC_MAX_BPP(dsc->max_bpp)));
>
> /*
> * FIXME: This is ugly, and slice count should take DSC engine diff --git
> a/drivers/gpu/drm/i915/display/intel_cdclk.c
> b/drivers/gpu/drm/i915/display/intel_cdclk.c
> index ad5251ba6fe1..06a1e99a2762 100644
> --- a/drivers/gpu/drm/i915/display/intel_cdclk.c
> +++ b/drivers/gpu/drm/i915/display/intel_cdclk.c
> @@ -2567,7 +2567,7 @@ static int intel_vdsc_min_cdclk(const struct
> intel_crtc_state *crtc_state)
> * => CDCLK >= compressed_bpp * Pixel clock / 2 * Bigjoiner
> Interface bits
> */
> int bigjoiner_interface_bits = DISPLAY_VER(i915) > 13 ? 36 : 24;
> - int min_cdclk_bj = (crtc_state->dsc.compressed_bpp *
> pixel_clock) /
> + int min_cdclk_bj = (to_bpp_int(crtc_state-
> >dsc.compressed_bpp_x16) *
> +pixel_clock) /
> (2 * bigjoiner_interface_bits);
>
> min_cdclk = max(min_cdclk, min_cdclk_bj); diff --git
> a/drivers/gpu/drm/i915/display/intel_display.c
> b/drivers/gpu/drm/i915/display/intel_display.c
> index 83e1bc858b9f..afcbdd4f105a 100644
> --- a/drivers/gpu/drm/i915/display/intel_display.c
> +++ b/drivers/gpu/drm/i915/display/intel_display.c
> @@ -5365,7 +5365,7 @@ intel_pipe_config_compare(const struct
> intel_crtc_state *current_config,
>
> PIPE_CONF_CHECK_I(dsc.compression_enable);
> PIPE_CONF_CHECK_I(dsc.dsc_split);
> - PIPE_CONF_CHECK_I(dsc.compressed_bpp);
> + PIPE_CONF_CHECK_I(dsc.compressed_bpp_x16);
>
> PIPE_CONF_CHECK_BOOL(splitter.enable);
> PIPE_CONF_CHECK_I(splitter.link_count);
> diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h
> b/drivers/gpu/drm/i915/display/intel_display_types.h
> index c21064794f32..9eb7b8912076 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> @@ -1353,7 +1353,8 @@ struct intel_crtc_state {
> struct {
> bool compression_enable;
> bool dsc_split;
> - u16 compressed_bpp;
> + /* Compressed Bpp in U6.4 format (first 4 bits for fractional
> part) */
> + u16 compressed_bpp_x16;
> u8 slice_count;
> struct drm_dsc_config config;
> } dsc;
> @@ -2108,4 +2109,19 @@ to_intel_frontbuffer(struct drm_framebuffer *fb)
> return fb ? to_intel_framebuffer(fb)->frontbuffer : NULL; }
>
> +static inline int to_bpp_int(int bpp_x16) {
> + return bpp_x16 >> 4;
> +}
> +
> +static inline int to_bpp_frac_dec(int bpp_x16) {
> + return (bpp_x16 & 0xf) * 625;
> +}
Let's add a comment on top on why we apply the mask and where the value 625 comes from
Something like:
"Since compressed bpp is now fractional such that last 4 bits represent fractional bits we get the
fractional part by multiplying by 10000 then dividing it by 16 as we initially left shift compressed bpp by 4,
to get 4 bits for the fractional part"
Otherwise,
LGTM.
Reviewed-by: Suraj Kandpal <suraj.kandpal@xxxxxxxxx
> +
> +static inline int to_bpp_x16(int bpp)
> +{
> + return bpp << 4;
> +}
> +
> #endif /* __INTEL_DISPLAY_TYPES_H__ */ diff --git
> a/drivers/gpu/drm/i915/display/intel_dp.c
> b/drivers/gpu/drm/i915/display/intel_dp.c
> index 2206b45bc78c..9b88ac3a73c7 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -1863,7 +1863,7 @@ icl_dsc_compute_link_config(struct intel_dp
> *intel_dp,
> valid_dsc_bpp[i],
> timeslots);
> if (ret == 0) {
> - pipe_config->dsc.compressed_bpp = valid_dsc_bpp[i];
> + pipe_config->dsc.compressed_bpp_x16 =
> to_bpp_x16(valid_dsc_bpp[i]);
> return 0;
> }
> }
> @@ -1901,7 +1901,7 @@ xelpd_dsc_compute_link_config(struct intel_dp
> *intel_dp,
> compressed_bpp,
> timeslots);
> if (ret == 0) {
> - pipe_config->dsc.compressed_bpp =
> compressed_bpp;
> + pipe_config->dsc.compressed_bpp_x16 =
> to_bpp_x16(compressed_bpp);
> return 0;
> }
> }
> @@ -2085,7 +2085,7 @@ static int intel_edp_dsc_compute_pipe_bpp(struct
> intel_dp *intel_dp,
> /* Compressed BPP should be less than the Input DSC bpp */
> dsc_max_bpp = min(dsc_max_bpp, pipe_bpp - 1);
>
> - pipe_config->dsc.compressed_bpp = max(dsc_min_bpp,
> dsc_max_bpp);
> + pipe_config->dsc.compressed_bpp_x16 =
> to_bpp_x16(max(dsc_min_bpp,
> +dsc_max_bpp));
>
> pipe_config->pipe_bpp = pipe_bpp;
>
> @@ -2172,17 +2172,19 @@ int intel_dp_dsc_compute_config(struct intel_dp
> *intel_dp,
> if (ret < 0) {
> drm_dbg_kms(&dev_priv->drm,
> "Cannot compute valid DSC parameters for Input
> Bpp = %d "
> - "Compressed BPP = %d\n",
> + "Compressed BPP = %d.%d\n",
> pipe_config->pipe_bpp,
> - pipe_config->dsc.compressed_bpp);
> + to_bpp_int(pipe_config->dsc.compressed_bpp_x16),
> + to_bpp_frac_dec(pipe_config-
> >dsc.compressed_bpp_x16));
> return ret;
> }
>
> pipe_config->dsc.compression_enable = true;
> drm_dbg_kms(&dev_priv->drm, "DP DSC computed with Input Bpp =
> %d "
> - "Compressed Bpp = %d Slice Count = %d\n",
> + "Compressed Bpp = %d.%d Slice Count = %d\n",
> pipe_config->pipe_bpp,
> - pipe_config->dsc.compressed_bpp,
> + to_bpp_int(pipe_config->dsc.compressed_bpp_x16),
> + to_bpp_frac_dec(pipe_config->dsc.compressed_bpp_x16),
> pipe_config->dsc.slice_count);
>
> return 0;
> @@ -2261,15 +2263,16 @@ intel_dp_compute_link_config(struct
> intel_encoder *encoder,
>
> if (pipe_config->dsc.compression_enable) {
> drm_dbg_kms(&i915->drm,
> - "DP lane count %d clock %d Input bpp %d
> Compressed bpp %d\n",
> + "DP lane count %d clock %d Input bpp %d
> Compressed bpp %d.%d\n",
> pipe_config->lane_count, pipe_config->port_clock,
> pipe_config->pipe_bpp,
> - pipe_config->dsc.compressed_bpp);
> + to_bpp_int(pipe_config->dsc.compressed_bpp_x16),
> + to_bpp_frac_dec(pipe_config-
> >dsc.compressed_bpp_x16));
>
> drm_dbg_kms(&i915->drm,
> "DP link rate required %i available %i\n",
> intel_dp_link_required(adjusted_mode->crtc_clock,
> - pipe_config-
> >dsc.compressed_bpp),
> + to_bpp_int(pipe_config-
> >dsc.compressed_bpp_x16)),
> intel_dp_max_data_rate(pipe_config->port_clock,
> pipe_config->lane_count));
> } else {
> @@ -2702,7 +2705,7 @@ intel_dp_compute_config(struct intel_encoder
> *encoder,
> intel_dp_limited_color_range(pipe_config, conn_state);
>
> if (pipe_config->dsc.compression_enable)
> - link_bpp = pipe_config->dsc.compressed_bpp;
> + link_bpp = pipe_config->dsc.compressed_bpp_x16;
> else
> link_bpp = intel_dp_output_bpp(pipe_config->output_format,
> pipe_config->pipe_bpp);
> diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> index 2d1c42a5e684..68a81f10e772 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> @@ -140,7 +140,7 @@ static int intel_dp_mst_find_vcpi_slots_for_bpp(struct
> intel_encoder *encoder,
> if (!dsc)
> crtc_state->pipe_bpp = bpp;
> else
> - crtc_state->dsc.compressed_bpp = bpp;
> + crtc_state->dsc.compressed_bpp_x16 =
> to_bpp_x16(bpp);
> drm_dbg_kms(&i915->drm, "Got %d slots for pipe bpp %d dsc
> %d\n", slots, bpp, dsc);
> }
>
> @@ -238,13 +238,13 @@ static int
> intel_dp_dsc_mst_compute_link_config(struct intel_encoder *encoder,
> if (slots < 0)
> return slots;
>
> - last_compressed_bpp = crtc_state->dsc.compressed_bpp;
> + last_compressed_bpp = to_bpp_int(crtc_state-
> >dsc.compressed_bpp_x16);
>
> - crtc_state->dsc.compressed_bpp =
> intel_dp_dsc_nearest_valid_bpp(i915,
> -
> last_compressed_bpp,
> -
> crtc_state->pipe_bpp);
> + crtc_state->dsc.compressed_bpp_x16 =
> +
> to_bpp_x16(intel_dp_dsc_nearest_valid_bpp(i915,
> last_compressed_bpp,
> +
> crtc_state->pipe_bpp));
>
> - if (crtc_state->dsc.compressed_bpp != last_compressed_bpp)
> + if (crtc_state->dsc.compressed_bpp_x16 !=
> +to_bpp_x16(last_compressed_bpp))
> need_timeslot_recalc = true;
>
> /*
> @@ -253,14 +253,14 @@ static int
> intel_dp_dsc_mst_compute_link_config(struct intel_encoder *encoder,
> */
> 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,
> +
> to_bpp_int(crtc_state->dsc.compressed_bpp_x16),
> +
> to_bpp_int(crtc_state->dsc.compressed_bpp_x16),
> limits, conn_state,
> 2 * 3, true);
> if (slots < 0)
> return slots;
> }
>
> - intel_link_compute_m_n(crtc_state->dsc.compressed_bpp,
> + intel_link_compute_m_n(to_bpp_int(crtc_state-
> >dsc.compressed_bpp_x16),
> crtc_state->lane_count,
> adjusted_mode->crtc_clock,
> crtc_state->port_clock,
> diff --git a/drivers/gpu/drm/i915/display/intel_vdsc.c
> b/drivers/gpu/drm/i915/display/intel_vdsc.c
> index b24601d0b2c5..bfc41972a0bb 100644
> --- a/drivers/gpu/drm/i915/display/intel_vdsc.c
> +++ b/drivers/gpu/drm/i915/display/intel_vdsc.c
> @@ -248,7 +248,7 @@ int intel_dsc_compute_params(struct intel_crtc_state
> *pipe_config)
> struct intel_crtc *crtc = to_intel_crtc(pipe_config->uapi.crtc);
> struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
> struct drm_dsc_config *vdsc_cfg = &pipe_config->dsc.config;
> - u16 compressed_bpp = pipe_config->dsc.compressed_bpp;
> + u16 compressed_bpp = to_bpp_int(pipe_config-
> >dsc.compressed_bpp_x16);
> int err;
> int ret;
>
> @@ -878,7 +878,7 @@ static void intel_dsc_get_pps_config(struct
> intel_crtc_state *crtc_state)
> if (vdsc_cfg->native_420)
> vdsc_cfg->bits_per_pixel >>= 1;
>
> - crtc_state->dsc.compressed_bpp = vdsc_cfg->bits_per_pixel >> 4;
> + crtc_state->dsc.compressed_bpp_x16 = vdsc_cfg->bits_per_pixel;
>
> /* PPS_2 */
> intel_dsc_read_and_verify_pps_reg(crtc_state, 2, &pps_temp);
> --
> 2.25.1
