Mandate a minimum Hblank symbol cycle count between BS and BE in 8b/10b
MST and 128b/132b mode.
Spec: DP2.1a
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)
Signed-off-by: Arun R Murthy <arun.r.murthy@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 | 35 ++++++++++++++++++++++
drivers/gpu/drm/i915/i915_reg.h | 4 +++
4 files changed, 41 insertions(+)
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..7d3a7700c44ef200d811d9e90ea465c06104287e 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; /* min HBlank for DP2.1 */
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..bd561c08d945fcafa65af9254a71cd66f17923d2 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
@@ -211,6 +211,35 @@ 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);
+
+ /* bit 8:0 minimum hblank symbol cylce count, i.e maximum value would be 511 */
+ hblank = min(511, hblank);
+
+ /* Software needs to adjust the BS/BE framing control from the calculated value */
+ hblank = hblank - 2;
+
+ if (intel_dp_is_uhbr(crtc_state))
+ crtc_state->min_hblank = max(hblank, 5);
+ else
+ crtc_state->min_hblank = max(hblank, 3);
+}
+
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 +313,8 @@ 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,
@@ -1267,6 +1298,10 @@ static void mst_stream_enable(struct intel_atomic_state *state,
TRANS_DP2_VFREQ_PIXEL_CLOCK(crtc_clock_hz & 0xffffff));
}
+ if (DISPLAY_VER(display) >= 20)
+ intel_de_write(display, DP_MIN_HBLANK_CTL(trans),
+ pipe_config->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>
