Mandate a minimum Hblank symbol cycle count between BlankingStart and
BlankingEnd in 8b/10b MST and 128b/132b mode.
v2: Affine calculation/updation of min HBlank to dp_mst (Jani)
v3: moved min_hblank from struct intel_dp to intel_crtc_state (Jani)
v4: use max/min functions, change intel_xx *intel_xx to intel_xx *xx
(Jani)
Limit hblank to 511 and accommodate BS/BE in calculated value
(Srikanth)
v5: Some spelling corrections (Suraj)
v6: Removed DP2.1 in comment as this is applicable for both DP2.1 and
DP1.4 (Suraj)
v7: crtc_state holds the logical values and the register value
computation is moved to mst_enable() (Jani)
Bspec: 74379
Signed-off-by: Arun R Murthy <arun.r.murthy@xxxxxxxxx>
Reviewed-by: Suraj Kandpal <suraj.kandpal@xxxxxxxxx>
---
Changes in v7:
- EDITME: describe what is new in this series revision.
- EDITME: use bulletpoints and terse descriptions.
- Link to v6: https://lore.kernel.org/r/20250103-hblank-v6-1-c2f749181fc6@xxxxxxxxx
Changes in v6:
- EDITME: describe what is new in this series revision.
- EDITME: use bulletpoints and terse descriptions.
- Link to v5: https://lore.kernel.org/r/20250103-hblank-v5-1-269a8748cf5b@xxxxxxxxx
---
.../gpu/drm/i915/display/intel_crtc_state_dump.c | 1 +
drivers/gpu/drm/i915/display/intel_display_types.h | 1 +
drivers/gpu/drm/i915/display/intel_dp_mst.c | 52 +++++++++++++++++++++-
drivers/gpu/drm/i915/i915_reg.h | 4 ++
4 files changed, 57 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/display/intel_crtc_state_dump.c b/drivers/gpu/drm/i915/display/intel_crtc_state_dump.c
index 1faef60be4728cd80a0a6b0151797ceda5c443ce..0e7e0b7803d9865177d6f68e8afdef94a91d9697 100644
--- a/drivers/gpu/drm/i915/display/intel_crtc_state_dump.c
+++ b/drivers/gpu/drm/i915/display/intel_crtc_state_dump.c
@@ -248,6 +248,7 @@ void intel_crtc_state_dump(const struct intel_crtc_state *pipe_config,
str_enabled_disabled(pipe_config->has_sel_update),
str_enabled_disabled(pipe_config->has_panel_replay),
str_enabled_disabled(pipe_config->enable_psr2_sel_fetch));
+ drm_printf(&p, "minimum HBlank: %d\n", pipe_config->min_hblank);
}
drm_printf(&p, "framestart delay: %d, MSA timing delay: %d\n",
diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
index eb9dd1125a4a09511936b81219e7f38fae106dfd..96467be97ae64aa40e985d0272016860b666c119 100644
--- a/drivers/gpu/drm/i915/display/intel_display_types.h
+++ b/drivers/gpu/drm/i915/display/intel_display_types.h
@@ -1095,6 +1095,7 @@ struct intel_crtc_state {
int max_link_bpp_x16; /* in 1/16 bpp units */
int pipe_bpp; /* in 1 bpp units */
+ int min_hblank;
struct intel_link_m_n dp_m_n;
/* m2_n2 for eDP downclock */
diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c
index fffd199999e02eb66ea478ff872f72b277bd3970..afd5ac1939a38f1d81be372c0fc370d996286159 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
@@ -211,6 +211,28 @@ 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,
+ struct intel_connector *connector,
+ int bpp_x16)
+{
+ struct intel_encoder *encoder = connector->encoder;
+ struct intel_display *display = to_intel_display(encoder);
+ 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;
+}
+
static int mst_stream_find_vcpi_slots_for_bpp(struct intel_dp *intel_dp,
struct intel_crtc_state *crtc_state,
int max_bpp, int min_bpp,
@@ -284,6 +306,8 @@ static int mst_stream_find_vcpi_slots_for_bpp(struct intel_dp *intel_dp,
remote_bw_overhead = intel_dp_mst_bw_overhead(crtc_state, connector,
true, dsc_slice_count, link_bpp_x16);
+ intel_dp_mst_compute_min_hblank(crtc_state, connector, link_bpp_x16);
+
intel_dp_mst_compute_m_n(crtc_state, connector,
local_bw_overhead,
link_bpp_x16,
@@ -1252,7 +1276,7 @@ static void mst_stream_enable(struct intel_atomic_state *state,
enum transcoder trans = pipe_config->cpu_transcoder;
bool first_mst_stream = intel_dp->active_mst_links == 1;
struct intel_crtc *pipe_crtc;
- int ret, i;
+ int ret, i, min_hblank;
drm_WARN_ON(display->drm, pipe_config->has_pch_encoder);
@@ -1267,6 +1291,32 @@ static void mst_stream_enable(struct intel_atomic_state *state,
TRANS_DP2_VFREQ_PIXEL_CLOCK(crtc_clock_hz & 0xffffff));
}
+ if (DISPLAY_VER(display) >= 20) {
+ /*
+ * bit 8:0 minimum hblank symbol cylce count, i.e maximum value
+ * would be 511
+ */
+ min_hblank = min(511, pipe_config->min_hblank);
+
+ /*
+ * adjust the BlankingStart/BlankingEnd framing control from
+ * the calculated value
+ */
+ min_hblank = min_hblank - 2;
+
+ /*
+ * 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);
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 765e6c0528fb0b5a894395b77a5edbf0b0c80009..7bd783931199e2e5c7e15358bb4d2c904f28176a 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -3197,6 +3197,10 @@
#define _TRANS_DP2_VFREQLOW_D 0x630a8
#define TRANS_DP2_VFREQLOW(trans) _MMIO_TRANS(trans, _TRANS_DP2_VFREQLOW_A, _TRANS_DP2_VFREQLOW_B)
+#define _DP_MIN_HBLANK_CTL_A 0x600ac
+#define _DP_MIN_HBLANK_CTL_B 0x610ac
+#define DP_MIN_HBLANK_CTL(trans) _MMIO_TRANS(trans, _DP_MIN_HBLANK_CTL_A, _DP_MIN_HBLANK_CTL_B)
+
/* SNB eDP training params */
/* SNB A-stepping */
#define EDP_LINK_TRAIN_400MV_0DB_SNB_A (0x38 << 22)
---
base-commit: 048d83e7f9dae81c058d31c371634c1c317b3013
change-id: 20250103-hblank-cd7e78cbe178
Best regards,
--
Arun R Murthy <arun.r.murthy@xxxxxxxxx>
