On Mon, Sep 23, 2019 at 05:57:57PM +0300, Ville Syrjälä wrote:
> On Mon, Sep 23, 2019 at 04:49:47PM +0200, Maarten Lankhorst wrote:
> > There was a integer wraparound when mode_clock became too high,
> > and we didn't correct for the FEC overhead factor when dividing,
> > with the calculations breaking at HBR3.
> >
> > As a result our calculated bpp was way too high, and the link width
> > limitation never came into effect.
> >
> > Print out the resulting bpp calcululations as a sanity check, just
> > in case we ever have to debug it later on again.
> >
> > We also used the wrong factor for FEC. While bspec mentions 2.4%,
> > all the calculations use 1/0.972261, and the same ratio should be
> > applied to data M/N as well, so use it there when FEC is enabled.
> >
> > Make sure we don't break hw readout, and read out FEC enable state
> > and correct the DDI clock readout for the new values.
> >
> > This fixes the FIFO underrun we are seeing with FEC enabled.
> >
> > Changes since v2:
> > - Handle fec_enable in intel_link_compute_m_n, so only data M/N is adjusted. (Ville)
> > - Fix initial hardware readout for FEC. (Ville)
> > Changes since v3:
> > - Remove bogus fec_to_mode_clock. (Ville)
> >
> > Signed-off-by: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
> > Fixes: d9218c8f6cf4 ("drm/i915/dp: Add helpers for Compressed BPP and Slice Count for DSC")
> > Cc: <stable@xxxxxxxxxxxxxxx> # v5.0+
> > Cc: Manasi Navare <manasi.d.navare@xxxxxxxxx>
> > ---
> > drivers/gpu/drm/i915/display/intel_ddi.c | 17 ++
> > drivers/gpu/drm/i915/display/intel_display.c | 13 +-
> > drivers/gpu/drm/i915/display/intel_display.h | 2 +-
> > drivers/gpu/drm/i915/display/intel_dp.c | 184 ++++++++++---------
> > drivers/gpu/drm/i915/display/intel_dp.h | 6 +-
> > drivers/gpu/drm/i915/display/intel_dp_mst.c | 2 +-
> > 6 files changed, 125 insertions(+), 99 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
> > index 0c0da9f6c2e8..1cb297abd111 100644
> > --- a/drivers/gpu/drm/i915/display/intel_ddi.c
> > +++ b/drivers/gpu/drm/i915/display/intel_ddi.c
> > @@ -4045,6 +4045,23 @@ void intel_ddi_get_config(struct intel_encoder *encoder,
> > pipe_config->lane_count =
> > ((temp & DDI_PORT_WIDTH_MASK) >> DDI_PORT_WIDTH_SHIFT) + 1;
> > intel_dp_get_m_n(intel_crtc, pipe_config);
> > +
> > + if (INTEL_GEN(dev_priv) >= 11) {
> > + i915_reg_t dp_tp_ctl;
> > +
> > + if (IS_GEN(dev_priv, 11))
> > + dp_tp_ctl = DP_TP_CTL(pipe_config->cpu_transcoder);
Oh, and pre-tgl DP_TP_CTL is per port.
> > + else
> > + dp_tp_ctl = TGL_DP_TP_CTL(pipe_config->cpu_transcoder);
> > +
> > + pipe_config->fec_enable =
> > + I915_READ(dp_tp_ctl) & DP_TP_CTL_FEC_ENABLE;
>
> Can you split the fec_enable readout/state check into a separate
> patch?
>
> I wonder how the lack of this stuff was missed when FEC was adeed...
>
> > +
> > + DRM_DEBUG_KMS("[ENCODER:%d:%s] Fec status: %u\n",
> > + encoder->base.base.id, encoder->base.name,
> > + pipe_config->fec_enable);
>
> I'd just include it as part of the normal state dump.
>
> > + }
> > +
> > break;
> > case TRANS_DDI_MODE_SELECT_DP_MST:
> > pipe_config->output_types |= BIT(INTEL_OUTPUT_DP_MST);
> > diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> > index 5ecf54270181..31698a57773f 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display.c
> > +++ b/drivers/gpu/drm/i915/display/intel_display.c
> > @@ -7291,7 +7291,7 @@ 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,
> > - link_bw, &pipe_config->fdi_m_n, false);
> > + link_bw, &pipe_config->fdi_m_n, false, false);
> >
> > ret = ironlake_check_fdi_lanes(dev, intel_crtc->pipe, pipe_config);
> > if (ret == -EDEADLK)
> > @@ -7538,11 +7538,15 @@ void
> > intel_link_compute_m_n(u16 bits_per_pixel, int nlanes,
> > int pixel_clock, int link_clock,
> > struct intel_link_m_n *m_n,
> > - bool constant_n)
> > + bool constant_n, bool fec_enable)
> > {
> > - m_n->tu = 64;
> > + u32 data_clock = bits_per_pixel * pixel_clock;
> > +
> > + if (fec_enable)
> > + data_clock = intel_dp_mode_to_fec_clock(data_clock);
> >
> > - compute_m_n(bits_per_pixel * pixel_clock,
> > + m_n->tu = 64;
> > + compute_m_n(data_clock,
> > link_clock * nlanes * 8,
> > &m_n->gmch_m, &m_n->gmch_n,
> > constant_n);
> > @@ -12832,6 +12836,7 @@ intel_pipe_config_compare(const struct intel_crtc_state *current_config,
> > PIPE_CONF_CHECK_BOOL(hdmi_scrambling);
> > PIPE_CONF_CHECK_BOOL(hdmi_high_tmds_clock_ratio);
> > PIPE_CONF_CHECK_BOOL(has_infoframe);
> > + PIPE_CONF_CHECK_BOOL(fec_enable);
> >
> > PIPE_CONF_CHECK_BOOL_INCOMPLETE(has_audio);
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_display.h b/drivers/gpu/drm/i915/display/intel_display.h
> > index 5cea6f8e107a..4b9e18e5a263 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display.h
> > +++ b/drivers/gpu/drm/i915/display/intel_display.h
> > @@ -443,7 +443,7 @@ enum phy_fia {
> > void intel_link_compute_m_n(u16 bpp, int nlanes,
> > int pixel_clock, int link_clock,
> > struct intel_link_m_n *m_n,
> > - bool constant_n);
> > + bool constant_n, bool fec_enable);
> > bool is_ccs_modifier(u64 modifier);
> > void lpt_disable_clkout_dp(struct drm_i915_private *dev_priv);
> > u32 intel_plane_fb_max_stride(struct drm_i915_private *dev_priv,
> > diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> > index 829559f97440..2b1e71f992b0 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> > @@ -76,8 +76,8 @@
> > #define DP_DSC_MAX_ENC_THROUGHPUT_0 340000
> > #define DP_DSC_MAX_ENC_THROUGHPUT_1 400000
> >
> > -/* DP DSC FEC Overhead factor = (100 - 2.4)/100 */
> > -#define DP_DSC_FEC_OVERHEAD_FACTOR 976
> > +/* DP DSC FEC Overhead factor = 1/(0.972261) */
> > +#define DP_DSC_FEC_OVERHEAD_FACTOR 972261
> >
> > /* Compliance test status bits */
> > #define INTEL_DP_RESOLUTION_SHIFT_MASK 0
> > @@ -492,6 +492,97 @@ int intel_dp_get_link_train_fallback_values(struct intel_dp *intel_dp,
> > return 0;
> > }
> >
> > +u32 intel_dp_mode_to_fec_clock(u32 mode_clock)
> > +{
> > + return div_u64(mul_u32_u32(mode_clock, 1000000U),
> > + DP_DSC_FEC_OVERHEAD_FACTOR);
> > +}
> > +
> > +static u16 intel_dp_dsc_get_output_bpp(u32 link_clock, u32 lane_count,
> > + u32 mode_clock, u32 mode_hdisplay)
> > +{
> > + u32 bits_per_pixel, max_bpp_small_joiner_ram;
> > + int i;
> > +
> > + /*
> > + * Available Link Bandwidth(Kbits/sec) = (NumberOfLanes)*
> > + * (LinkSymbolClock)* 8 * (TimeSlotsPerMTP)
> > + * for SST -> TimeSlotsPerMTP is 1,
> > + * for MST -> TimeSlotsPerMTP has to be calculated
> > + */
> > + bits_per_pixel = (link_clock * lane_count * 8) /
> > + intel_dp_mode_to_fec_clock(mode_clock);
> > + DRM_DEBUG_KMS("Max link bpp: %u\n", bits_per_pixel);
> > +
> > + /* Small Joiner Check: output bpp <= joiner RAM (bits) / Horiz. width */
> > + max_bpp_small_joiner_ram = DP_DSC_MAX_SMALL_JOINER_RAM_BUFFER / mode_hdisplay;
> > + DRM_DEBUG_KMS("Max small joiner bpp: %u\n", max_bpp_small_joiner_ram);
> > +
> > + /*
> > + * Greatest allowed DSC BPP = MIN (output BPP from available Link BW
> > + * check, output bpp from small joiner RAM check)
> > + */
> > + bits_per_pixel = min(bits_per_pixel, max_bpp_small_joiner_ram);
> > +
> > + /* Error out if the max bpp is less than smallest allowed valid bpp */
> > + if (bits_per_pixel < valid_dsc_bpp[0]) {
> > + DRM_DEBUG_KMS("Unsupported BPP %u, min %u\n",
> > + bits_per_pixel, valid_dsc_bpp[0]);
> > + return 0;
> > + }
> > +
> > + /* Find the nearest match in the array of known BPPs from VESA */
> > + for (i = 0; i < ARRAY_SIZE(valid_dsc_bpp) - 1; i++) {
> > + if (bits_per_pixel < valid_dsc_bpp[i + 1])
> > + break;
> > + }
> > + bits_per_pixel = valid_dsc_bpp[i];
> > +
> > + /*
> > + * Compressed BPP in U6.4 format so multiply by 16, for Gen 11,
> > + * fractional part is 0
> > + */
> > + return bits_per_pixel << 4;
> > +}
> > +
> > +static u8 intel_dp_dsc_get_slice_count(struct intel_dp *intel_dp,
> > + int mode_clock, int mode_hdisplay)
> > +{
> > + u8 min_slice_count, i;
> > + int max_slice_width;
> > +
> > + if (mode_clock <= DP_DSC_PEAK_PIXEL_RATE)
> > + min_slice_count = DIV_ROUND_UP(mode_clock,
> > + DP_DSC_MAX_ENC_THROUGHPUT_0);
> > + else
> > + min_slice_count = DIV_ROUND_UP(mode_clock,
> > + DP_DSC_MAX_ENC_THROUGHPUT_1);
> > +
> > + max_slice_width = drm_dp_dsc_sink_max_slice_width(intel_dp->dsc_dpcd);
> > + if (max_slice_width < DP_DSC_MIN_SLICE_WIDTH_VALUE) {
> > + DRM_DEBUG_KMS("Unsupported slice width %d by DP DSC Sink device\n",
> > + max_slice_width);
> > + return 0;
> > + }
> > + /* Also take into account max slice width */
> > + min_slice_count = min_t(u8, min_slice_count,
> > + DIV_ROUND_UP(mode_hdisplay,
> > + max_slice_width));
> > +
> > + /* Find the closest match to the valid slice count values */
> > + for (i = 0; i < ARRAY_SIZE(valid_dsc_slicecount); i++) {
> > + if (valid_dsc_slicecount[i] >
> > + drm_dp_dsc_sink_max_slice_count(intel_dp->dsc_dpcd,
> > + false))
> > + break;
> > + if (min_slice_count <= valid_dsc_slicecount[i])
> > + return valid_dsc_slicecount[i];
> > + }
> > +
> > + DRM_DEBUG_KMS("Unsupported Slice Count %d\n", min_slice_count);
> > + return 0;
> > +}
> > +
> > static enum drm_mode_status
> > intel_dp_mode_valid(struct drm_connector *connector,
> > struct drm_display_mode *mode)
> > @@ -2259,7 +2350,7 @@ intel_dp_compute_config(struct intel_encoder *encoder,
> > adjusted_mode->crtc_clock,
> > pipe_config->port_clock,
> > &pipe_config->dp_m_n,
> > - constant_n);
> > + constant_n, pipe_config->fec_enable);
> >
> > if (intel_connector->panel.downclock_mode != NULL &&
> > dev_priv->drrs.type == SEAMLESS_DRRS_SUPPORT) {
> > @@ -2269,7 +2360,7 @@ intel_dp_compute_config(struct intel_encoder *encoder,
> > intel_connector->panel.downclock_mode->clock,
> > pipe_config->port_clock,
> > &pipe_config->dp_m2_n2,
> > - constant_n);
> > + constant_n, pipe_config->fec_enable);
> > }
> >
> > if (!HAS_DDI(dev_priv))
> > @@ -4373,91 +4464,6 @@ intel_dp_get_sink_irq_esi(struct intel_dp *intel_dp, u8 *sink_irq_vector)
> > DP_DPRX_ESI_LEN;
> > }
> >
> > -u16 intel_dp_dsc_get_output_bpp(int link_clock, u8 lane_count,
> > - int mode_clock, int mode_hdisplay)
> > -{
> > - u16 bits_per_pixel, max_bpp_small_joiner_ram;
> > - int i;
> > -
> > - /*
> > - * Available Link Bandwidth(Kbits/sec) = (NumberOfLanes)*
> > - * (LinkSymbolClock)* 8 * ((100-FECOverhead)/100)*(TimeSlotsPerMTP)
> > - * FECOverhead = 2.4%, for SST -> TimeSlotsPerMTP is 1,
> > - * for MST -> TimeSlotsPerMTP has to be calculated
> > - */
> > - bits_per_pixel = (link_clock * lane_count * 8 *
> > - DP_DSC_FEC_OVERHEAD_FACTOR) /
> > - mode_clock;
> > -
> > - /* Small Joiner Check: output bpp <= joiner RAM (bits) / Horiz. width */
> > - max_bpp_small_joiner_ram = DP_DSC_MAX_SMALL_JOINER_RAM_BUFFER /
> > - mode_hdisplay;
> > -
> > - /*
> > - * Greatest allowed DSC BPP = MIN (output BPP from avaialble Link BW
> > - * check, output bpp from small joiner RAM check)
> > - */
> > - bits_per_pixel = min(bits_per_pixel, max_bpp_small_joiner_ram);
> > -
> > - /* Error out if the max bpp is less than smallest allowed valid bpp */
> > - if (bits_per_pixel < valid_dsc_bpp[0]) {
> > - DRM_DEBUG_KMS("Unsupported BPP %d\n", bits_per_pixel);
> > - return 0;
> > - }
> > -
> > - /* Find the nearest match in the array of known BPPs from VESA */
> > - for (i = 0; i < ARRAY_SIZE(valid_dsc_bpp) - 1; i++) {
> > - if (bits_per_pixel < valid_dsc_bpp[i + 1])
> > - break;
> > - }
> > - bits_per_pixel = valid_dsc_bpp[i];
> > -
> > - /*
> > - * Compressed BPP in U6.4 format so multiply by 16, for Gen 11,
> > - * fractional part is 0
> > - */
> > - return bits_per_pixel << 4;
> > -}
> > -
> > -u8 intel_dp_dsc_get_slice_count(struct intel_dp *intel_dp,
> > - int mode_clock,
> > - int mode_hdisplay)
> > -{
> > - u8 min_slice_count, i;
> > - int max_slice_width;
> > -
> > - if (mode_clock <= DP_DSC_PEAK_PIXEL_RATE)
> > - min_slice_count = DIV_ROUND_UP(mode_clock,
> > - DP_DSC_MAX_ENC_THROUGHPUT_0);
> > - else
> > - min_slice_count = DIV_ROUND_UP(mode_clock,
> > - DP_DSC_MAX_ENC_THROUGHPUT_1);
> > -
> > - max_slice_width = drm_dp_dsc_sink_max_slice_width(intel_dp->dsc_dpcd);
> > - if (max_slice_width < DP_DSC_MIN_SLICE_WIDTH_VALUE) {
> > - DRM_DEBUG_KMS("Unsupported slice width %d by DP DSC Sink device\n",
> > - max_slice_width);
> > - return 0;
> > - }
> > - /* Also take into account max slice width */
> > - min_slice_count = min_t(u8, min_slice_count,
> > - DIV_ROUND_UP(mode_hdisplay,
> > - max_slice_width));
> > -
> > - /* Find the closest match to the valid slice count values */
> > - for (i = 0; i < ARRAY_SIZE(valid_dsc_slicecount); i++) {
> > - if (valid_dsc_slicecount[i] >
> > - drm_dp_dsc_sink_max_slice_count(intel_dp->dsc_dpcd,
> > - false))
> > - break;
> > - if (min_slice_count <= valid_dsc_slicecount[i])
> > - return valid_dsc_slicecount[i];
> > - }
> > -
> > - DRM_DEBUG_KMS("Unsupported Slice Count %d\n", min_slice_count);
> > - return 0;
> > -}
> > -
> > static void
> > intel_pixel_encoding_setup_vsc(struct intel_dp *intel_dp,
> > const struct intel_crtc_state *crtc_state)
> > diff --git a/drivers/gpu/drm/i915/display/intel_dp.h b/drivers/gpu/drm/i915/display/intel_dp.h
> > index e01d1f89409d..a194b5b6da05 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dp.h
> > +++ b/drivers/gpu/drm/i915/display/intel_dp.h
> > @@ -103,10 +103,6 @@ bool intel_dp_source_supports_hbr2(struct intel_dp *intel_dp);
> > bool intel_dp_source_supports_hbr3(struct intel_dp *intel_dp);
> > bool
> > intel_dp_get_link_status(struct intel_dp *intel_dp, u8 *link_status);
> > -u16 intel_dp_dsc_get_output_bpp(int link_clock, u8 lane_count,
> > - int mode_clock, int mode_hdisplay);
> > -u8 intel_dp_dsc_get_slice_count(struct intel_dp *intel_dp, int mode_clock,
> > - int mode_hdisplay);
> >
> > bool intel_dp_read_dpcd(struct intel_dp *intel_dp);
> > bool intel_dp_get_colorimetry_status(struct intel_dp *intel_dp);
> > @@ -119,4 +115,6 @@ static inline unsigned int intel_dp_unused_lane_mask(int lane_count)
> > return ~((1 << lane_count) - 1) & 0xf;
> > }
> >
> > +u32 intel_dp_mode_to_fec_clock(u32 mode_clock);
> > +
> > #endif /* __INTEL_DP_H__ */
> > diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > index eeeb3f933aa4..cf4d851a5139 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> > @@ -81,7 +81,7 @@ static int intel_dp_mst_compute_link_config(struct intel_encoder *encoder,
> > adjusted_mode->crtc_clock,
> > crtc_state->port_clock,
> > &crtc_state->dp_m_n,
> > - constant_n);
> > + constant_n, crtc_state->fec_enable);
> > crtc_state->dp_m_n.tu = slots;
> >
> > return 0;
> > --
> > 2.20.1
>
> --
> Ville Syrjälä
> Intel
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx
--
Ville Syrjälä
Intel
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