Thanks for the comments, please some my answers below:
On Mon, Nov 19, 2018 at 10:11:04PM +0200, Ville Syrjälä wrote:
> On Tue, Nov 13, 2018 at 05:52:16PM -0800, Manasi Navare wrote:
> > DSC params like the enable, compressed bpp, slice count and
> > dsc_split are added to the intel_crtc_state. These parameters
> > are set based on the requested mode and available link parameters
> > during the pipe configuration in atomic check phase.
> > These values are then later used to populate the remaining DSC
> > and RC parameters before enbaling DSC in atomic commit.
> >
> > v13:
> > * Compute DSC bpc only when DSC is req to be enabled (Ville)
> > v12:
> > * Override bpp with dsc dpcd color depth (Manasi)
> > v11:
> > * Const crtc_state, reject DSC on DP without FEC (Ville)
> > * Dont set dsc_split to false (Ville)
> > v10:
> > * Add a helper for dp_dsc support (Ville)
> > * Set pipe_config to max bpp, link params for DSC for now (Ville)
> > * Compute bpp - use dp dsc support helper (Ville)
> > v9:
> > * Rebase on top of drm-tip that now uses fast_narrow config
> > for edp (Manasi)
> > v8:
> > * Check for DSC bpc not 0 (manasi)
> >
> > v7:
> > * Fix indentation in compute_m_n (Manasi)
> >
> > v6 (From Gaurav):
> > * Remove function call of intel_dp_compute_dsc_params() and
> > invoke intel_dp_compute_dsc_params() in the patch where
> > it is defined to fix compilation warning (Gaurav)
> >
> > v5:
> > Add drm_dsc_cfg in intel_crtc_state (Manasi)
> >
> > v4:
> > * Rebase on refactoring of intel_dp_compute_config on tip (Manasi)
> > * Add a comment why we need to check PSR while enabling DSC (Gaurav)
> >
> > v3:
> > * Check PPR > max_cdclock to use 2 VDSC instances (Ville)
> >
> > v2:
> > * Add if-else for eDP/DP (Gaurav)
> >
> > Cc: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx>
> > Cc: Ville Syrjala <ville.syrjala@xxxxxxxxxxxxxxx>
> > Cc: Anusha Srivatsa <anusha.srivatsa@xxxxxxxxx>
> > Cc: Gaurav K Singh <gaurav.k.singh@xxxxxxxxx>
> > Signed-off-by: Manasi Navare <manasi.d.navare@xxxxxxxxx>
> > Reviewed-by: Anusha Srivatsa <anusha.srivatsa@xxxxxxxxx>
> > Acked-by: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx>
> > ---
> > drivers/gpu/drm/i915/intel_display.c | 20 ++-
> > drivers/gpu/drm/i915/intel_display.h | 3 +-
> > drivers/gpu/drm/i915/intel_dp.c | 187 ++++++++++++++++++++++++---
> > drivers/gpu/drm/i915/intel_dp_mst.c | 2 +-
> > 4 files changed, 184 insertions(+), 28 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> > index 132e978227fb..390c4b3970db 100644
> > --- a/drivers/gpu/drm/i915/intel_display.c
> > +++ b/drivers/gpu/drm/i915/intel_display.c
> > @@ -6483,7 +6483,7 @@ static int ironlake_fdi_compute_config(struct intel_crtc *intel_crtc,
> >
> > pipe_config->fdi_lanes = lane;
> >
> > - intel_link_compute_m_n(pipe_config->pipe_bpp, lane, fdi_dotclock,
> > + intel_link_compute_m_n(pipe_config->pipe_bpp, 0, lane, fdi_dotclock,
> > link_bw, &pipe_config->fdi_m_n, false);
> >
> > ret = ironlake_check_fdi_lanes(dev, intel_crtc->pipe, pipe_config);
> > @@ -6723,17 +6723,25 @@ static void compute_m_n(unsigned int m, unsigned int n,
> > }
> >
> > void
> > -intel_link_compute_m_n(int bits_per_pixel, int nlanes,
> > +intel_link_compute_m_n(int bits_per_pixel, uint16_t compressed_bpp,
> > + int nlanes,
> > int pixel_clock, int link_clock,
> > struct intel_link_m_n *m_n,
> > bool constant_n)
> > {
> > m_n->tu = 64;
> >
> > - compute_m_n(bits_per_pixel * pixel_clock,
> > - link_clock * nlanes * 8,
> > - &m_n->gmch_m, &m_n->gmch_n,
> > - constant_n);
> > + /* For DSC, Data M/N calculation uses compressed BPP */
> > + if (compressed_bpp)
>
> The extra parameter seems to be pointless. Just pass
> compressed_bpp instead of pipe_bpp and it'll do what
> you want.
So if compressed_bpp then just pass compressed_bpp instead of bits_per_pixel,
is that what you are suggesting? Because we dont want to call compressed_bpp otherwise.
>
> > + compute_m_n(compressed_bpp * pixel_clock,
> > + link_clock * nlanes * 8,
> > + &m_n->gmch_m, &m_n->gmch_n,
> > + constant_n);
> > + else
> > + compute_m_n(bits_per_pixel * pixel_clock,
> > + link_clock * nlanes * 8,
> > + &m_n->gmch_m, &m_n->gmch_n,
> > + constant_n);
> >
> > compute_m_n(pixel_clock, link_clock,
> > &m_n->link_m, &m_n->link_n,
> > diff --git a/drivers/gpu/drm/i915/intel_display.h b/drivers/gpu/drm/i915/intel_display.h
> > index 5d50decbcbb5..b0b23e1e9392 100644
> > --- a/drivers/gpu/drm/i915/intel_display.h
> > +++ b/drivers/gpu/drm/i915/intel_display.h
> > @@ -407,7 +407,8 @@ struct intel_link_m_n {
> > (__i)++) \
> > for_each_if(plane)
> >
> > -void intel_link_compute_m_n(int bpp, int nlanes,
> > +void intel_link_compute_m_n(int bpp, uint16_t compressed_bpp,
> > + int nlanes,
> > int pixel_clock, int link_clock,
> > struct intel_link_m_n *m_n,
> > bool constant_n);
> > diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> > index 2b090609bee2..931c3c7e55c1 100644
> > --- a/drivers/gpu/drm/i915/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/intel_dp.c
> > @@ -47,6 +47,8 @@
> >
> > /* DP DSC small joiner has 2 FIFOs each of 640 x 6 bytes */
> > #define DP_DSC_MAX_SMALL_JOINER_RAM_BUFFER 61440
> > +#define DP_DSC_MIN_SUPPORTED_BPC 8
> > +#define DP_DSC_MAX_SUPPORTED_BPC 10
> >
> > /* DP DSC throughput values used for slice count calculations KPixels/s */
> > #define DP_DSC_PEAK_PIXEL_RATE 2720000
> > @@ -1708,6 +1710,29 @@ struct link_config_limits {
> > int min_bpp, max_bpp;
> > };
> >
> > +static bool intel_dp_source_supports_dsc(struct intel_dp *intel_dp,
> > + const struct intel_crtc_state *pipe_config)
> > +{
> > + struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
> > +
> > + /* FIXME: FEC needed for external DP until then reject DSC on DP */
> > + if (!intel_dp_is_edp(intel_dp))
> > + return false;
> > +
> > + return INTEL_GEN(dev_priv) >= 10 &&
> > + pipe_config->cpu_transcoder != TRANSCODER_A;
> > +}
> > +
> > +static bool intel_dp_supports_dsc(struct intel_dp *intel_dp,
> > + const struct intel_crtc_state *pipe_config)
> > +{
> > + if (!intel_dp_source_supports_dsc(intel_dp, pipe_config) ||
> > + !drm_dp_sink_supports_dsc(intel_dp->dsc_dpcd))
> > + return false;
>
> Or slightly more straightforward:
>
> return intel_dp_source_supports_dsc() &&
> drm_dp_sink_supports_dsc();
>
> I generally like to read these sort of things outloud to myself.
> That usually helps pick out the least convoluted form.
Cool will do.
>
> > +
> > + return true;
> > +}
> > +
> > static int intel_dp_compute_bpp(struct intel_dp *intel_dp,
> > struct intel_crtc_state *pipe_config)
> > {
> > @@ -1842,14 +1867,118 @@ intel_dp_compute_link_config_fast(struct intel_dp *intel_dp,
> > return false;
> > }
> >
> > +static int intel_dp_dsc_compute_bpp(struct intel_dp *intel_dp, u8 dsc_max_bpc)
> > +{
> > + int i;
> > + u8 dsc_sink_color_depth_cap[8] = {0};
>
> The variable name isn't very descriptive. Just bpc[], dsc_bpc[] etc. would
> seem better. And three elements should be all we need.
Yes
>
> > +
> > + drm_dp_dsc_sink_color_depth_cap(intel_dp->dsc_dpcd,
> > + dsc_sink_color_depth_cap);
>
> The function name isn't all that descriptive either.
> drm_dp_dsc_supported_input_bpcs() maybe?
>
> > + for (i = 0; i < ARRAY_SIZE(dsc_sink_color_depth_cap); i++) {
> > + if (dsc_max_bpc <= dsc_sink_color_depth_cap[i])
>
> This test seems the wrong way around.
We have to find the first value in dsc_sink_color_depth_cap array that
is less than or equal to dsc_max_bpc and return that right?
So yes this should dsc_max_bpc >= dsc_sink_max_color_depth_cap
MAnasi
>
> > + return dsc_sink_color_depth_cap[i] * 3;
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static bool intel_dp_dsc_compute_config(struct intel_dp *intel_dp,
> > + struct intel_crtc_state *pipe_config,
> > + struct drm_connector_state *conn_state,
> > + struct link_config_limits *limits)
> > +{
> > + struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
> > + struct drm_i915_private *dev_priv = to_i915(dig_port->base.base.dev);
> > + struct drm_display_mode *adjusted_mode = &pipe_config->base.adjusted_mode;
> > + u8 dsc_max_bpc;
> > + u16 dsc_max_output_bpp = 0;
> > + u8 dsc_dp_slice_count = 0;
> > + int pipe_bpp;
> > +
> > + if (!intel_dp_supports_dsc(intel_dp, pipe_config))
> > + return false;
> > +
> > + dsc_max_bpc = min_t(u8, DP_DSC_MAX_SUPPORTED_BPC,
> > + conn_state->max_requested_bpc);
> > +
> > + if (dsc_max_bpc < DP_DSC_MIN_SUPPORTED_BPC) {
> > + DRM_DEBUG_KMS("No DSC support for less than 8bpc\n");
> > + return false;
> > + }
>
> We don't really need this check here. intel_dp_dsc_compute_bpp()
> will return 0 if the max is below any supported value. So we can
> rely on the check afterwards.
>
> > + pipe_bpp = intel_dp_dsc_compute_bpp(intel_dp, dsc_max_bpc);
> > + if (!pipe_bpp || pipe_bpp < DP_DSC_MIN_SUPPORTED_BPC * 3) {
>
> The !pipe_bpp check is redundant.
>
> > + DRM_DEBUG_KMS("No DSC support for less than 8bpc\n");
> > + return false;
> > + }
> > +
> > + /*
> > + * For now enable DSC for max bpp, 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->pipe_bpp = pipe_bpp;
> > + pipe_config->port_clock = intel_dp->common_rates[limits->max_clock];
> > + pipe_config->lane_count = limits->max_lane_count;
> > +
> > + if (intel_dp_is_edp(intel_dp)) {
> > + pipe_config->dsc_params.compressed_bpp =
> > + min_t(u16, drm_edp_dsc_sink_output_bpp(intel_dp->dsc_dpcd) >> 4,
> > + pipe_config->pipe_bpp);
> > + pipe_config->dsc_params.slice_count =
> > + drm_dp_dsc_sink_max_slice_count(intel_dp->dsc_dpcd,
> > + true);
> > + } else {
> > + dsc_max_output_bpp =
> > + intel_dp_dsc_get_output_bpp(pipe_config->port_clock,
> > + pipe_config->lane_count,
> > + adjusted_mode->crtc_clock,
> > + adjusted_mode->crtc_hdisplay);
> > + dsc_dp_slice_count =
> > + intel_dp_dsc_get_slice_count(intel_dp,
> > + adjusted_mode->crtc_clock,
> > + adjusted_mode->crtc_hdisplay);
> > + if (!(dsc_max_output_bpp && dsc_dp_slice_count)) {
> > + DRM_DEBUG_KMS("Compressed BPP/Slice Count not supported\n");
> > + return false;
> > + }
> > + pipe_config->dsc_params.compressed_bpp = min_t(u16,
> > + dsc_max_output_bpp >> 4,
> > + pipe_config->pipe_bpp);
> > + pipe_config->dsc_params.slice_count = dsc_dp_slice_count;
> > + }
> > + /*
> > + * VDSC engine operates at 1 Pixel per clock, so if peak pixel rate
> > + * is greater than the maximum Cdclock and if slice count is even
> > + * then we need to use 2 VDSC instances.
> > + */
> > + if (adjusted_mode->crtc_clock > dev_priv->max_cdclk_freq) {
> > + if (pipe_config->dsc_params.slice_count > 1) {
> > + pipe_config->dsc_params.dsc_split = true;
> > + } else {
> > + DRM_DEBUG_KMS("Cannot split stream to use 2 VDSC instances\n");
> > + return false;
> > + }
> > + }
> > + pipe_config->dsc_params.compression_enable = true;
> > + DRM_DEBUG_KMS("DP DSC computed with Input Bpp = %d "
> > + "Compressed Bpp = %d Slice Count = %d\n",
> > + pipe_config->pipe_bpp,
> > + pipe_config->dsc_params.compressed_bpp,
> > + pipe_config->dsc_params.slice_count);
> > +
> > + return true;
> > +}
> > +
> > static bool
> > intel_dp_compute_link_config(struct intel_encoder *encoder,
> > - struct intel_crtc_state *pipe_config)
> > + struct intel_crtc_state *pipe_config,
> > + struct drm_connector_state *conn_state)
> > {
> > struct drm_display_mode *adjusted_mode = &pipe_config->base.adjusted_mode;
> > struct intel_dp *intel_dp = enc_to_intel_dp(&encoder->base);
> > struct link_config_limits limits;
> > int common_len;
> > + bool ret = false;
>
> Unecessary initialization AFAICS.
>
> >
> > common_len = intel_dp_common_len_rate_limit(intel_dp,
> > intel_dp->max_link_rate);
> > @@ -1863,8 +1992,8 @@ intel_dp_compute_link_config(struct intel_encoder *encoder,
> > limits.min_lane_count = 1;
> > limits.max_lane_count = intel_dp_max_lane_count(intel_dp);
> >
> > - limits.min_bpp = 6 * 3;
> > limits.max_bpp = intel_dp_compute_bpp(intel_dp, pipe_config);
> > + limits.min_bpp = 6 * 3;
>
> Leftovers
>
> >
> > if (intel_dp_is_edp(intel_dp) && intel_dp->edp_dpcd[0] < DP_EDP_14) {
> > /*
> > @@ -1888,7 +2017,7 @@ intel_dp_compute_link_config(struct intel_encoder *encoder,
> > intel_dp->common_rates[limits.max_clock],
> > limits.max_bpp, adjusted_mode->crtc_clock);
> >
> > - if (intel_dp_is_edp(intel_dp)) {
> > + if (intel_dp_is_edp(intel_dp))
> > /*
> > * Optimize for fast and narrow. eDP 1.3 section 3.3 and eDP 1.4
> > * section A.1: "It is recommended that the minimum number of
> > @@ -1898,26 +2027,42 @@ intel_dp_compute_link_config(struct intel_encoder *encoder,
> > * Note that we use the max clock and lane count for eDP 1.3 and
> > * earlier, and fast vs. wide is irrelevant.
> > */
> > - if (!intel_dp_compute_link_config_fast(intel_dp, pipe_config,
> > - &limits))
> > - return false;
> > - } else {
> > + ret = intel_dp_compute_link_config_fast(intel_dp, pipe_config,
> > + &limits);
> > + else
> > /* Optimize for slow and wide. */
> > - if (!intel_dp_compute_link_config_wide(intel_dp, pipe_config,
> > - &limits))
> > + ret = intel_dp_compute_link_config_wide(intel_dp, pipe_config,
> > + &limits);
> > +
> > + /* enable compression if the mode doesn't fit available BW */
> > + if (!ret) {
> > + if (!intel_dp_dsc_compute_config(intel_dp, pipe_config,
> > + conn_state, &limits))
> > return false;
> > }
> >
> > - DRM_DEBUG_KMS("DP lane count %d clock %d bpp %d\n",
> > - pipe_config->lane_count, pipe_config->port_clock,
> > - pipe_config->pipe_bpp);
> > + if (pipe_config->dsc_params.compression_enable) {
> > + DRM_DEBUG_KMS("DP lane count %d clock %d Input bpp %d Compressed bpp %d\n",
> > + pipe_config->lane_count, pipe_config->port_clock,
> > + pipe_config->pipe_bpp,
> > + pipe_config->dsc_params.compressed_bpp);
> >
> > - DRM_DEBUG_KMS("DP link rate required %i available %i\n",
> > - intel_dp_link_required(adjusted_mode->crtc_clock,
> > - pipe_config->pipe_bpp),
> > - intel_dp_max_data_rate(pipe_config->port_clock,
> > - pipe_config->lane_count));
> > + DRM_DEBUG_KMS("DP link rate required %i available %i\n",
> > + intel_dp_link_required(adjusted_mode->crtc_clock,
> > + pipe_config->dsc_params.compressed_bpp),
> > + intel_dp_max_data_rate(pipe_config->port_clock,
> > + pipe_config->lane_count));
> > + } else {
> > + DRM_DEBUG_KMS("DP lane count %d clock %d bpp %d\n",
> > + pipe_config->lane_count, pipe_config->port_clock,
> > + pipe_config->pipe_bpp);
> >
> > + DRM_DEBUG_KMS("DP link rate required %i available %i\n",
> > + intel_dp_link_required(adjusted_mode->crtc_clock,
> > + pipe_config->pipe_bpp),
> > + intel_dp_max_data_rate(pipe_config->port_clock,
> > + pipe_config->lane_count));
> > + }
> > return true;
> > }
> >
> > @@ -1983,7 +2128,7 @@ intel_dp_compute_config(struct intel_encoder *encoder,
> > if (adjusted_mode->flags & DRM_MODE_FLAG_DBLCLK)
> > return false;
> >
> > - if (!intel_dp_compute_link_config(encoder, pipe_config))
> > + if (!intel_dp_compute_link_config(encoder, pipe_config, conn_state))
> > return false;
> >
> > if (intel_conn_state->broadcast_rgb == INTEL_BROADCAST_RGB_AUTO) {
> > @@ -2001,7 +2146,9 @@ intel_dp_compute_config(struct intel_encoder *encoder,
> > intel_conn_state->broadcast_rgb == INTEL_BROADCAST_RGB_LIMITED;
> > }
> >
> > - intel_link_compute_m_n(pipe_config->pipe_bpp, pipe_config->lane_count,
> > + intel_link_compute_m_n(pipe_config->pipe_bpp,
> > + pipe_config->dsc_params.compressed_bpp,
> > + pipe_config->lane_count,
> > adjusted_mode->crtc_clock,
> > pipe_config->port_clock,
> > &pipe_config->dp_m_n,
> > @@ -2010,7 +2157,7 @@ intel_dp_compute_config(struct intel_encoder *encoder,
> > if (intel_connector->panel.downclock_mode != NULL &&
> > dev_priv->drrs.type == SEAMLESS_DRRS_SUPPORT) {
> > pipe_config->has_drrs = true;
> > - intel_link_compute_m_n(pipe_config->pipe_bpp,
> > + intel_link_compute_m_n(pipe_config->pipe_bpp, 0,
> > pipe_config->lane_count,
> > intel_connector->panel.downclock_mode->clock,
> > pipe_config->port_clock,
> > diff --git a/drivers/gpu/drm/i915/intel_dp_mst.c b/drivers/gpu/drm/i915/intel_dp_mst.c
> > index 4de247ddf05f..3f346b2e3b48 100644
> > --- a/drivers/gpu/drm/i915/intel_dp_mst.c
> > +++ b/drivers/gpu/drm/i915/intel_dp_mst.c
> > @@ -90,7 +90,7 @@ static bool intel_dp_mst_compute_config(struct intel_encoder *encoder,
> > }
> > }
> >
> > - intel_link_compute_m_n(bpp, lane_count,
> > + intel_link_compute_m_n(bpp, 0, lane_count,
> > adjusted_mode->crtc_clock,
> > pipe_config->port_clock,
> > &pipe_config->dp_m_n,
> > --
> > 2.19.1
>
> --
> Ville Syrjälä
> Intel
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