[PATCH v4 2/2] drm/i915/display: move min_hblank from dp_mst.c to dp.c
Arun R Murthy
arun.r.murthy at intel.com
Wed Apr 23 09:37:40 UTC 2025
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.
TODO: Add the min_hblank calculation for hdmi as well.
v2: move from intel_audio.c to intel_dp.c
some correction in link_bpp_x16 (Imre)
v3: min_hblank for 8b/10b MST and 128b/132b SST/MST
handle error for intel_dp_mst_dsc_get_slice_count
reset min_hblank before disabling transcoder (Imre)
v4: compute link_bpp_x16 within compute_min_hblank,
return error in case of compute failure
call compute_min_hblank() before vrr_compute_config (Imre)
Signed-off-by: Arun R Murthy <arun.r.murthy at intel.com>
---
drivers/gpu/drm/i915/display/intel_display.c | 17 +++++++
drivers/gpu/drm/i915/display/intel_dp.c | 76 ++++++++++++++++++++++++++++
drivers/gpu/drm/i915/display/intel_dp.h | 3 ++
drivers/gpu/drm/i915/display/intel_dp_mst.c | 57 +++------------------
4 files changed, 102 insertions(+), 51 deletions(-)
diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index 33c09999c42e046c7a8b6e6143be0b81650ee7f7..6425296d99f408582cd10d9ffdae94beb2ea2521 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -2723,6 +2723,19 @@ static void intel_set_transcoder_timings(const struct intel_crtc_state *crtc_sta
intel_de_write(display, TRANS_VTOTAL(display, pipe),
VACTIVE(crtc_vdisplay - 1) |
VTOTAL(crtc_vtotal - 1));
+
+ 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);
+ }
}
static void intel_set_transcoder_timings_lrr(const struct intel_crtc_state *crtc_state)
@@ -2866,6 +2879,8 @@ static void intel_get_transcoder_timings(struct intel_crtc *crtc,
adjusted_mode->crtc_vdisplay +
intel_de_read(display,
TRANS_SET_CONTEXT_LATENCY(display, cpu_transcoder));
+ pipe_config->min_hblank = intel_de_read(display,
+ DP_MIN_HBLANK_CTL(cpu_transcoder));
}
static void intel_joiner_adjust_pipe_src(struct intel_crtc_state *crtc_state)
@@ -5216,6 +5231,8 @@ intel_pipe_config_compare(const struct intel_crtc_state *current_config,
PIPE_CONF_CHECK_I(lane_count);
PIPE_CONF_CHECK_X(lane_lat_optim_mask);
+ PIPE_CONF_CHECK_I(min_hblank);
+
if (HAS_DOUBLE_BUFFERED_M_N(display)) {
if (!fastset || !pipe_config->update_m_n)
PIPE_CONF_CHECK_M_N(dp_m_n);
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index d7a30d0992b7a65250a3abfecde876321326fa84..c18889cecaf40cd6599adbb3ae0f0feb0c95990f 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -3104,6 +3104,77 @@ intel_dp_queue_modeset_retry_for_link(struct intel_atomic_state *state,
}
}
+int intel_dp_compute_min_hblank(struct intel_crtc_state *crtc_state,
+ struct drm_connector_state *conn_state,
+ bool is_dsc)
+{
+ 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;
+ /*
+ * min symbol cycles is 3(BS,VBID, BE) for 128b/132b and
+ * 5(BS, VBID, MVID, MAUD, BE) for 8b/10b
+ */
+ int min_sym_cycles = intel_dp_is_uhbr(crtc_state) ? 3 : 5;
+ bool is_mst = intel_crtc_has_type(crtc_state, INTEL_OUTPUT_DP_MST);
+ int num_joined_pipes = intel_crtc_num_joined_pipes(crtc_state);
+ int min_hblank;
+ int max_lane_count = 4;
+ int hactive_sym_cycles, htotal_sym_cycles;
+ int dsc_slices = 0;
+ int link_bpp_x16;
+
+ if (DISPLAY_VER(display) < 30)
+ return 0;
+
+ /* MIN_HBLANK should be set only for 8b/10b MST or for 128b/132b SST/MST */
+ if (!is_mst && !intel_dp_is_uhbr(crtc_state))
+ return 0;
+
+ if (is_dsc) {
+ dsc_slices = intel_dp_dsc_get_slice_count(connector,
+ adjusted_mode->crtc_clock,
+ adjusted_mode->crtc_hdisplay,
+ num_joined_pipes);
+ if (!dsc_slices) {
+ drm_dbg(display->drm, "failed to calculate dsc slice count\n");
+ return -EINVAL;
+ }
+ }
+
+ if (crtc_state->dsc.compression_enable)
+ link_bpp_x16 = crtc_state->dsc.compressed_bpp_x16;
+ else
+ link_bpp_x16 = fxp_q4_from_int(intel_dp_output_bpp(crtc_state->output_format,
+ crtc_state->pipe_bpp));
+
+ /* Calculate min Hblank Link Layer Symbol Cycle Count for 8b/10b MST & 128b/132b */
+ hactive_sym_cycles = drm_dp_link_symbol_cycles(max_lane_count,
+ adjusted_mode->hdisplay,
+ dsc_slices,
+ link_bpp_x16,
+ symbol_size, is_mst);
+ htotal_sym_cycles = (adjusted_mode->htotal * hactive_sym_cycles) /
+ adjusted_mode->hdisplay;
+
+ 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;
+
+ min_hblank = min(10, min_hblank);
+ crtc_state->min_hblank = min_hblank;
+
+ return 0;
+}
+
int
intel_dp_compute_config(struct intel_encoder *encoder,
struct intel_crtc_state *pipe_config,
@@ -3203,6 +3274,11 @@ intel_dp_compute_config(struct intel_encoder *encoder,
&pipe_config->dp_m_n);
}
+ ret = intel_dp_compute_min_hblank(pipe_config, conn_state,
+ pipe_config->dsc.compression_enable);
+ if (ret)
+ return ret;
+
/* FIXME: abstract this better */
if (pipe_config->splitter.enable)
pipe_config->dp_m_n.data_m *= pipe_config->splitter.link_count;
diff --git a/drivers/gpu/drm/i915/display/intel_dp.h b/drivers/gpu/drm/i915/display/intel_dp.h
index 9189db4c25946a0f082223ce059c242e80cc32dc..6f2f048295ecaa6cc1f967dc7b3b4cc75f3344c0 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.h
+++ b/drivers/gpu/drm/i915/display/intel_dp.h
@@ -208,5 +208,8 @@ bool intel_dp_has_connector(struct intel_dp *intel_dp,
const struct drm_connector_state *conn_state);
int intel_dp_dsc_max_src_input_bpc(struct intel_display *display);
int intel_dp_dsc_min_src_input_bpc(void);
+int intel_dp_compute_min_hblank(struct intel_crtc_state *crtc_state,
+ struct drm_connector_state *conn_state,
+ bool is_dsc);
#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 4c15dcb103aa2ed5650cbbef8c12be53132e6a80..1108c3749d812a45d1675297220dad23969750fe 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
@@ -239,26 +239,6 @@ static int intel_dp_mst_dsc_get_slice_count(const struct intel_connector *connec
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,
@@ -329,8 +309,6 @@ 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,
@@ -739,6 +717,11 @@ static int mst_stream_compute_config(struct intel_encoder *encoder,
pipe_config->lane_lat_optim_mask =
bxt_dpio_phy_calc_lane_lat_optim_mask(pipe_config->lane_count);
+ ret = intel_dp_compute_min_hblank(pipe_config, conn_state,
+ pipe_config->dsc.compression_enable);
+ if (ret)
+ return ret;
+
intel_vrr_compute_config(pipe_config, conn_state);
intel_dp_audio_compute_config(encoder, pipe_config, conn_state);
@@ -1021,12 +1004,10 @@ static void mst_stream_disable(struct intel_atomic_state *state,
const struct intel_crtc_state *old_crtc_state,
const struct drm_connector_state *old_conn_state)
{
- struct intel_display *display = to_intel_display(state);
struct intel_dp_mst_encoder *intel_mst = enc_to_mst(encoder);
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;
if (intel_dp_mst_active_streams(intel_dp) == 1)
intel_dp->link.active = false;
@@ -1034,9 +1015,6 @@ 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,
@@ -1305,7 +1283,7 @@ 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_streams(intel_dp) == 1;
struct intel_crtc *pipe_crtc;
- int ret, i, min_hblank;
+ int ret, i;
drm_WARN_ON(display->drm, pipe_config->has_pch_encoder);
@@ -1320,29 +1298,6 @@ 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
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