| Message ID | 20250408-hblank-v1-3-4ba17aebee65@intel.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Rework/Correction on minimum hblank calculation | expand |
On Tue, Apr 08, 2025 at 09:40:36AM +0530, Arun R Murthy wrote: > Minimum HBlank is programmed to address jitter for high resolutions with > high refresh rates that have small Hblank, specifically where Hblank is > smaller than one MTP. I wondered if following the standard practice of one change per commit is indeed not practical as you do it in this case. > > Signed-off-by: Arun R Murthy <arun.r.murthy@intel.com> > --- > drivers/gpu/drm/i915/display/intel_audio.c | 78 +++++++++++++++++++++++++++++ > drivers/gpu/drm/i915/display/intel_dp_mst.c | 51 +------------------ > 2 files changed, 79 insertions(+), 50 deletions(-) > > diff --git a/drivers/gpu/drm/i915/display/intel_audio.c b/drivers/gpu/drm/i915/display/intel_audio.c > index ea935a5d94c87202a68f84b28b0152835f47fe73..b73cb208a37c6d4928c1ce16d2ab689626dcbbc5 100644 > --- a/drivers/gpu/drm/i915/display/intel_audio.c > +++ b/drivers/gpu/drm/i915/display/intel_audio.c > @@ -27,9 +27,11 @@ > #include <drm/drm_edid.h> > #include <drm/drm_eld.h> > #include <drm/drm_fixed.h> > +#include <drm/display/drm_dp_helper.h> > #include <drm/intel/i915_component.h> > > #include "i915_drv.h" > +#include "i915_reg.h" > #include "intel_atomic.h" > #include "intel_audio.h" > #include "intel_audio_regs.h" > @@ -37,6 +39,8 @@ > #include "intel_crtc.h" > #include "intel_de.h" > #include "intel_display_types.h" > +#include "intel_dp.h" > +#include "intel_dp_mst.h" > #include "intel_lpe_audio.h" > > /** > @@ -184,6 +188,62 @@ static const struct hdmi_aud_ncts hdmi_aud_ncts_36bpp[] = { > { 192000, TMDS_445_5M, 20480, 371250 }, > }; > > +static void intel_audio_compute_min_hblank(struct intel_crtc_state *crtc_state, > + struct drm_connector_state *conn_state) I don't see any audio specific parameters in the calculation. This function is also called for non-DP encoders (HDMI) and for DP encoders it's called only if the DP sink supports audio. Isn't it supposed to be a generic (not audio specific) DP state calculated elsewhere (intel_dp.c)? > +{ > + struct intel_display *display = to_intel_display(crtc_state); > + const struct drm_display_mode *adjusted_mode = > + &crtc_state->hw.adjusted_mode; > + struct intel_connector *connector = to_intel_connector(conn_state->connector); > + int symbol_size = intel_dp_is_uhbr(crtc_state) ? 32 : 8; > + int min_sym_cycles = intel_dp_is_uhbr(crtc_state) ? 3 : 5; Would be good to figure out and comment here what the 3 and 5 symbols stand for. > + bool is_dsc = crtc_state->dsc.compression_enable; > + int bpp = is_dsc ? crtc_state->dsc.compressed_bpp_x16 : > + crtc_state->pipe_bpp; This looks incorrect as the units for compressed_bpp_x16 and pipe_bpp are different. > + bool is_mst = intel_crtc_has_type(crtc_state, INTEL_OUTPUT_DP_MST); > + u8 lane_count = crtc_state->lane_count; > + int min_hblank, htotal, hactive; I don't think it's worth adding separate variables for lane_count, htotal, hactive. > + int hactive_sym_cycles, htotal_sym_cycles; > + int dsc_slices = intel_dp_mst_dsc_get_slice_count(connector, > + crtc_state); > + > + if (DISPLAY_VER(display) < 30) > + return; > + > + /* Calculate min Hblank Link Layer Symbol Cycle Count for 8b/10b MST & 128b/132b */ > + hactive = adjusted_mode->hdisplay; > + htotal = adjusted_mode->htotal; > + > + hactive_sym_cycles = is_dsc ? drm_dp_link_dsc_symbol_cycles(lane_count, To get LL instead of ML symbol cycles as required by bspec, you should pass here lane_count=4 always, independent of the actual lane_count in crtc_state. > + hactive, > + dsc_slices, > + bpp, > + symbol_size, > + is_mst) : > + drm_dp_link_symbol_cycles(lane_count, > + hactive, > + bpp, This expects bpp_x16 units, but pipe_bpp that would be passed here has different units. > + symbol_size, > + is_mst); > + htotal_sym_cycles = htotal * hactive_sym_cycles / hactive; > + > + min_hblank = DIV_ROUND_UP((htotal_sym_cycles * bpp), > + (4 * symbol_size)) - hactive_sym_cycles; Not sure what the above division adjusts for, I think it should be just min_hblank = htotal_sym_cycles - hactive_sym_cycles > + /* minimum Hblank calculation: https://groups.vesa.org/wg/DP/document/20494 */ > + min_hblank = max(min_hblank, min_sym_cycles); > + > + /* > + * adjust the BlankingStart/BlankingEnd framing control from > + * the calculated value > + */ > + min_hblank = min_hblank - 2; > + > + /* Maximum value to be programmed is limited to 10 */ > + min_hblank = min(10, min_hblank); > + crtc_state->min_hblank = min_hblank; > +} > + > + > /* > * WA_14020863754: Implement Audio Workaround > * Corner case with Min Hblank Fix can cause audio hang > @@ -715,6 +775,8 @@ bool intel_audio_compute_config(struct intel_encoder *encoder, > memcpy(crtc_state->eld, connector->eld, sizeof(crtc_state->eld)); > > crtc_state->eld[6] = drm_av_sync_delay(connector, adjusted_mode) / 2; > + > + intel_audio_compute_min_hblank(crtc_state, conn_state); > mutex_unlock(&connector->eld_mutex); > > return true; > @@ -778,6 +840,19 @@ void intel_audio_codec_enable(struct intel_encoder *encoder, > intel_lpe_audio_notify(display, cpu_transcoder, port, crtc_state->eld, > crtc_state->port_clock, > intel_crtc_has_dp_encoder(crtc_state)); > + > + if (DISPLAY_VER(display) >= 30) { > + /* > + * Address issues for resolutions with high refresh rate that > + * have small Hblank, specifically where Hblank is smaller than > + * one MTP. Simulations indicate this will address the > + * jitter issues that currently causes BS to be immediately > + * followed by BE which DPRX devices are unable to handle. > + * https://groups.vesa.org/wg/DP/document/20494 > + */ > + intel_de_write(display, DP_MIN_HBLANK_CTL(cpu_transcoder), > + crtc_state->min_hblank); > + } It's not clear why this programming is audio specific, based on my earlier comment above. > } > > /** > @@ -834,6 +909,9 @@ void intel_audio_codec_disable(struct intel_encoder *encoder, > } > > intel_lpe_audio_notify(display, cpu_transcoder, port, NULL, 0, false); > + > + if (DISPLAY_VER(display) >= 30) > + intel_de_write(display, DP_MIN_HBLANK_CTL(cpu_transcoder), 0); > } > > static void intel_acomp_get_config(struct intel_encoder *encoder, > diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c > index af98a0d0e8376a79ce1ab6ff3c4f6af30f4d3e73..dae74c645c1a1d716504b7843fe1a5c8ace0d87d 100644 > --- a/drivers/gpu/drm/i915/display/intel_dp_mst.c > +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c > @@ -211,26 +211,6 @@ int intel_dp_mst_dsc_get_slice_count(const struct intel_connector *connector, > num_joined_pipes); > } > > -static void intel_dp_mst_compute_min_hblank(struct intel_crtc_state *crtc_state, > - int bpp_x16) > -{ > - struct intel_display *display = to_intel_display(crtc_state); > - const struct drm_display_mode *adjusted_mode = > - &crtc_state->hw.adjusted_mode; > - int symbol_size = intel_dp_is_uhbr(crtc_state) ? 32 : 8; > - int hblank; > - > - if (DISPLAY_VER(display) < 20) > - return; > - > - /* Calculate min Hblank Link Layer Symbol Cycle Count for 8b/10b MST & 128b/132b */ > - hblank = DIV_ROUND_UP((DIV_ROUND_UP > - (adjusted_mode->htotal - adjusted_mode->hdisplay, 4) * bpp_x16), > - symbol_size); > - > - crtc_state->min_hblank = hblank; > -} > - > int intel_dp_mtp_tu_compute_config(struct intel_dp *intel_dp, > struct intel_crtc_state *crtc_state, > struct drm_connector_state *conn_state, > @@ -301,8 +281,6 @@ int intel_dp_mtp_tu_compute_config(struct intel_dp *intel_dp, > local_bw_overhead = intel_dp_mst_bw_overhead(crtc_state, > false, dsc_slice_count, link_bpp_x16); > > - intel_dp_mst_compute_min_hblank(crtc_state, link_bpp_x16); > - > intel_dp_mst_compute_m_n(crtc_state, > local_bw_overhead, > link_bpp_x16, > @@ -998,7 +976,6 @@ static void mst_stream_disable(struct intel_atomic_state *state, > struct intel_dp *intel_dp = to_primary_dp(encoder); > struct intel_connector *connector = > to_intel_connector(old_conn_state->connector); > - enum transcoder trans = old_crtc_state->cpu_transcoder; > > drm_dbg_kms(display->drm, "active links %d\n", > intel_dp->mst.active_links); > @@ -1009,9 +986,6 @@ static void mst_stream_disable(struct intel_atomic_state *state, > intel_hdcp_disable(intel_mst->connector); > > intel_dp_sink_disable_decompression(state, connector, old_crtc_state); > - > - if (DISPLAY_VER(display) >= 20) > - intel_de_write(display, DP_MIN_HBLANK_CTL(trans), 0); > } > > static void mst_stream_post_disable(struct intel_atomic_state *state, > @@ -1286,7 +1260,7 @@ static void mst_stream_enable(struct intel_atomic_state *state, > enum transcoder trans = pipe_config->cpu_transcoder; > bool first_mst_stream = intel_dp->mst.active_links == 1; > struct intel_crtc *pipe_crtc; > - int ret, i, min_hblank; > + int ret, i; > > drm_WARN_ON(display->drm, pipe_config->has_pch_encoder); > > @@ -1301,29 +1275,6 @@ static void mst_stream_enable(struct intel_atomic_state *state, > TRANS_DP2_VFREQ_PIXEL_CLOCK(crtc_clock_hz & 0xffffff)); > } > > - if (DISPLAY_VER(display) >= 20) { > - /* > - * adjust the BlankingStart/BlankingEnd framing control from > - * the calculated value > - */ > - min_hblank = pipe_config->min_hblank - 2; > - > - /* Maximum value to be programmed is limited to 0x10 */ > - min_hblank = min(0x10, min_hblank); > - > - /* > - * Minimum hblank accepted for 128b/132b would be 5 and for > - * 8b/10b would be 3 symbol count > - */ > - if (intel_dp_is_uhbr(pipe_config)) > - min_hblank = max(min_hblank, 5); > - else > - min_hblank = max(min_hblank, 3); > - > - intel_de_write(display, DP_MIN_HBLANK_CTL(trans), > - min_hblank); > - } > - > enable_bs_jitter_was(pipe_config); > > intel_ddi_enable_transcoder_func(encoder, pipe_config); > > -- > 2.25.1 >
diff --git a/drivers/gpu/drm/i915/display/intel_audio.c b/drivers/gpu/drm/i915/display/intel_audio.c index ea935a5d94c87202a68f84b28b0152835f47fe73..b73cb208a37c6d4928c1ce16d2ab689626dcbbc5 100644 --- a/drivers/gpu/drm/i915/display/intel_audio.c +++ b/drivers/gpu/drm/i915/display/intel_audio.c @@ -27,9 +27,11 @@ #include <drm/drm_edid.h> #include <drm/drm_eld.h> #include <drm/drm_fixed.h> +#include <drm/display/drm_dp_helper.h> #include <drm/intel/i915_component.h> #include "i915_drv.h" +#include "i915_reg.h" #include "intel_atomic.h" #include "intel_audio.h" #include "intel_audio_regs.h" @@ -37,6 +39,8 @@ #include "intel_crtc.h" #include "intel_de.h" #include "intel_display_types.h" +#include "intel_dp.h" +#include "intel_dp_mst.h" #include "intel_lpe_audio.h" /** @@ -184,6 +188,62 @@ static const struct hdmi_aud_ncts hdmi_aud_ncts_36bpp[] = { { 192000, TMDS_445_5M, 20480, 371250 }, }; +static void intel_audio_compute_min_hblank(struct intel_crtc_state *crtc_state, + struct drm_connector_state *conn_state) +{ + struct intel_display *display = to_intel_display(crtc_state); + const struct drm_display_mode *adjusted_mode = + &crtc_state->hw.adjusted_mode; + struct intel_connector *connector = to_intel_connector(conn_state->connector); + int symbol_size = intel_dp_is_uhbr(crtc_state) ? 32 : 8; + int min_sym_cycles = intel_dp_is_uhbr(crtc_state) ? 3 : 5; + bool is_dsc = crtc_state->dsc.compression_enable; + int bpp = is_dsc ? crtc_state->dsc.compressed_bpp_x16 : + crtc_state->pipe_bpp; + bool is_mst = intel_crtc_has_type(crtc_state, INTEL_OUTPUT_DP_MST); + u8 lane_count = crtc_state->lane_count; + int min_hblank, htotal, hactive; + int hactive_sym_cycles, htotal_sym_cycles; + int dsc_slices = intel_dp_mst_dsc_get_slice_count(connector, + crtc_state); + + if (DISPLAY_VER(display) < 30) + return; + + /* Calculate min Hblank Link Layer Symbol Cycle Count for 8b/10b MST & 128b/132b */ + hactive = adjusted_mode->hdisplay; + htotal = adjusted_mode->htotal; + + hactive_sym_cycles = is_dsc ? drm_dp_link_dsc_symbol_cycles(lane_count, + hactive, + dsc_slices, + bpp, + symbol_size, + is_mst) : + drm_dp_link_symbol_cycles(lane_count, + hactive, + bpp, + symbol_size, + is_mst); + htotal_sym_cycles = htotal * hactive_sym_cycles / hactive; + + min_hblank = DIV_ROUND_UP((htotal_sym_cycles * bpp), + (4 * symbol_size)) - hactive_sym_cycles; + /* minimum Hblank calculation: https://groups.vesa.org/wg/DP/document/20494 */ + min_hblank = max(min_hblank, min_sym_cycles); + + /* + * adjust the BlankingStart/BlankingEnd framing control from + * the calculated value + */ + min_hblank = min_hblank - 2; + + /* Maximum value to be programmed is limited to 10 */ + min_hblank = min(10, min_hblank); + crtc_state->min_hblank = min_hblank; +} + + /* * WA_14020863754: Implement Audio Workaround * Corner case with Min Hblank Fix can cause audio hang @@ -715,6 +775,8 @@ bool intel_audio_compute_config(struct intel_encoder *encoder, memcpy(crtc_state->eld, connector->eld, sizeof(crtc_state->eld)); crtc_state->eld[6] = drm_av_sync_delay(connector, adjusted_mode) / 2; + + intel_audio_compute_min_hblank(crtc_state, conn_state); mutex_unlock(&connector->eld_mutex); return true; @@ -778,6 +840,19 @@ void intel_audio_codec_enable(struct intel_encoder *encoder, intel_lpe_audio_notify(display, cpu_transcoder, port, crtc_state->eld, crtc_state->port_clock, intel_crtc_has_dp_encoder(crtc_state)); + + if (DISPLAY_VER(display) >= 30) { + /* + * Address issues for resolutions with high refresh rate that + * have small Hblank, specifically where Hblank is smaller than + * one MTP. Simulations indicate this will address the + * jitter issues that currently causes BS to be immediately + * followed by BE which DPRX devices are unable to handle. + * https://groups.vesa.org/wg/DP/document/20494 + */ + intel_de_write(display, DP_MIN_HBLANK_CTL(cpu_transcoder), + crtc_state->min_hblank); + } } /** @@ -834,6 +909,9 @@ void intel_audio_codec_disable(struct intel_encoder *encoder, } intel_lpe_audio_notify(display, cpu_transcoder, port, NULL, 0, false); + + if (DISPLAY_VER(display) >= 30) + intel_de_write(display, DP_MIN_HBLANK_CTL(cpu_transcoder), 0); } static void intel_acomp_get_config(struct intel_encoder *encoder, diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c index af98a0d0e8376a79ce1ab6ff3c4f6af30f4d3e73..dae74c645c1a1d716504b7843fe1a5c8ace0d87d 100644 --- a/drivers/gpu/drm/i915/display/intel_dp_mst.c +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c @@ -211,26 +211,6 @@ int intel_dp_mst_dsc_get_slice_count(const struct intel_connector *connector, num_joined_pipes); } -static void intel_dp_mst_compute_min_hblank(struct intel_crtc_state *crtc_state, - int bpp_x16) -{ - struct intel_display *display = to_intel_display(crtc_state); - const struct drm_display_mode *adjusted_mode = - &crtc_state->hw.adjusted_mode; - int symbol_size = intel_dp_is_uhbr(crtc_state) ? 32 : 8; - int hblank; - - if (DISPLAY_VER(display) < 20) - return; - - /* Calculate min Hblank Link Layer Symbol Cycle Count for 8b/10b MST & 128b/132b */ - hblank = DIV_ROUND_UP((DIV_ROUND_UP - (adjusted_mode->htotal - adjusted_mode->hdisplay, 4) * bpp_x16), - symbol_size); - - crtc_state->min_hblank = hblank; -} - int intel_dp_mtp_tu_compute_config(struct intel_dp *intel_dp, struct intel_crtc_state *crtc_state, struct drm_connector_state *conn_state, @@ -301,8 +281,6 @@ int intel_dp_mtp_tu_compute_config(struct intel_dp *intel_dp, local_bw_overhead = intel_dp_mst_bw_overhead(crtc_state, false, dsc_slice_count, link_bpp_x16); - intel_dp_mst_compute_min_hblank(crtc_state, link_bpp_x16); - intel_dp_mst_compute_m_n(crtc_state, local_bw_overhead, link_bpp_x16, @@ -998,7 +976,6 @@ static void mst_stream_disable(struct intel_atomic_state *state, struct intel_dp *intel_dp = to_primary_dp(encoder); struct intel_connector *connector = to_intel_connector(old_conn_state->connector); - enum transcoder trans = old_crtc_state->cpu_transcoder; drm_dbg_kms(display->drm, "active links %d\n", intel_dp->mst.active_links); @@ -1009,9 +986,6 @@ static void mst_stream_disable(struct intel_atomic_state *state, intel_hdcp_disable(intel_mst->connector); intel_dp_sink_disable_decompression(state, connector, old_crtc_state); - - if (DISPLAY_VER(display) >= 20) - intel_de_write(display, DP_MIN_HBLANK_CTL(trans), 0); } static void mst_stream_post_disable(struct intel_atomic_state *state, @@ -1286,7 +1260,7 @@ static void mst_stream_enable(struct intel_atomic_state *state, enum transcoder trans = pipe_config->cpu_transcoder; bool first_mst_stream = intel_dp->mst.active_links == 1; struct intel_crtc *pipe_crtc; - int ret, i, min_hblank; + int ret, i; drm_WARN_ON(display->drm, pipe_config->has_pch_encoder); @@ -1301,29 +1275,6 @@ static void mst_stream_enable(struct intel_atomic_state *state, TRANS_DP2_VFREQ_PIXEL_CLOCK(crtc_clock_hz & 0xffffff)); } - if (DISPLAY_VER(display) >= 20) { - /* - * adjust the BlankingStart/BlankingEnd framing control from - * the calculated value - */ - min_hblank = pipe_config->min_hblank - 2; - - /* Maximum value to be programmed is limited to 0x10 */ - min_hblank = min(0x10, min_hblank); - - /* - * Minimum hblank accepted for 128b/132b would be 5 and for - * 8b/10b would be 3 symbol count - */ - if (intel_dp_is_uhbr(pipe_config)) - min_hblank = max(min_hblank, 5); - else - min_hblank = max(min_hblank, 3); - - intel_de_write(display, DP_MIN_HBLANK_CTL(trans), - min_hblank); - } - enable_bs_jitter_was(pipe_config); intel_ddi_enable_transcoder_func(encoder, pipe_config);
Minimum HBlank is programmed to address jitter for high resolutions with high refresh rates that have small Hblank, specifically where Hblank is smaller than one MTP. Signed-off-by: Arun R Murthy <arun.r.murthy@intel.com> --- drivers/gpu/drm/i915/display/intel_audio.c | 78 +++++++++++++++++++++++++++++ drivers/gpu/drm/i915/display/intel_dp_mst.c | 51 +------------------ 2 files changed, 79 insertions(+), 50 deletions(-)