Add a way for drivers to calculate the MST PBN values with FEC overhead.
This is required by 8b/10b links both for DSC and non-DSC (the latter
needed if there are both DSC and non-DSC streams on the same MST link).
Also add kunit test cases for PBN values calculated with FEC overhead.
Cc: Lyude Paul <lyude@xxxxxxxxxx>
Cc: Harry Wentland <harry.wentland@xxxxxxx>
Cc: Wayne Lin <wayne.lin@xxxxxxx>
Cc: Alex Deucher <alexander.deucher@xxxxxxx>
Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Imre Deak <imre.deak@xxxxxxxxx>
---
.../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 2 +-
.../display/amdgpu_dm/amdgpu_dm_mst_types.c | 2 +-
drivers/gpu/drm/display/drm_dp_mst_topology.c | 18 +++++++++++----
drivers/gpu/drm/i915/display/intel_dp_mst.c | 5 ++--
drivers/gpu/drm/nouveau/dispnv50/disp.c | 2 +-
.../gpu/drm/tests/drm_dp_mst_helper_test.c | 23 ++++++++++++++++++-
include/drm/display/drm_dp_mst_helper.h | 2 +-
7 files changed, 42 insertions(+), 12 deletions(-)
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index 268cb99a4c4bc..22868d6eb8977 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -6782,7 +6782,7 @@ static int dm_encoder_helper_atomic_check(struct drm_encoder *encoder,
max_bpc);
bpp = convert_dc_color_depth_into_bpc(color_depth) * 3;
clock = adjusted_mode->clock;
- dm_new_connector_state->pbn = drm_dp_calc_pbn_mode(clock, bpp, false);
+ dm_new_connector_state->pbn = drm_dp_calc_pbn_mode(clock, bpp, false, false);
}
dm_new_connector_state->vcpi_slots =
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
index 57230661132bd..9acfdefc792d6 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
@@ -1636,7 +1636,7 @@ enum dc_status dm_dp_mst_is_port_support_mode(
} else {
/* check if mode could be supported within full_pbn */
bpp = convert_dc_color_depth_into_bpc(stream->timing.display_color_depth) * 3;
- pbn = drm_dp_calc_pbn_mode(stream->timing.pix_clk_100hz / 10, bpp, false);
+ pbn = drm_dp_calc_pbn_mode(stream->timing.pix_clk_100hz / 10, bpp, false, false);
if (pbn > aconnector->mst_output_port->full_pbn)
return DC_FAIL_BANDWIDTH_VALIDATE;
diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c
index bd0f35a0ea5fb..e26f1b7f5a701 100644
--- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
@@ -4693,26 +4693,34 @@ EXPORT_SYMBOL(drm_dp_check_act_status);
* @clock: dot clock for the mode
* @bpp: bpp for the mode.
* @dsc: DSC mode. If true, bpp has units of 1/16 of a bit per pixel
+ * @fec: FEC overhead.
*
* This uses the formula in the spec to calculate the PBN value for a mode.
*/
-int drm_dp_calc_pbn_mode(int clock, int bpp, bool dsc)
+int drm_dp_calc_pbn_mode(int clock, int bpp, bool dsc, bool fec)
{
/*
- * margin 5300ppm + 300ppm ~ 0.6% as per spec, factor is 1.006
+ * Overheads:
+ * - SSC downspread and ref clock variation margin:
+ * 5300ppm + 300ppm ~ 0.6% as per spec, factor is 1.006
+ * - FEC symbol insertions:
+ * 2.4% as per spec, factor is 1.024
+ *
* The unit of 54/64Mbytes/sec is an arbitrary unit chosen based on
* common multiplier to render an integer PBN for all link rate/lane
* counts combinations
* calculate
- * peak_kbps *= (1006/1000)
+ * peak_kbps *= (1006/1000) without FEC, or
+ * peak_kbps *= (1030/1000) with FEC
* peak_kbps *= (64/54)
- * peak_kbps *= 8 convert to bytes
+ * peak_kbps /= 8 convert to bytes
*
* If the bpp is in units of 1/16, further divide by 16. Put this
* factor in the numerator rather than the denominator to avoid
* integer overflow
*/
- u32 bpp_m = (dsc ? 64 / 16 : 64) * 1006 * bpp;
+ u32 overhead = fec ? 1030 : 1006;
+ u32 bpp_m = (dsc ? 64 / 16 : 64) * overhead * bpp;
return DIV_ROUND_UP_ULL(mul_u32_u32(clock, bpp_m),
8 * 54 * 1000 * 1000);
diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c
index 525766206fce5..6eeb7dbf5ba67 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
@@ -110,7 +110,8 @@ static int intel_dp_mst_find_vcpi_slots_for_bpp(struct intel_encoder *encoder,
crtc_state->pbn = drm_dp_calc_pbn_mode(adjusted_mode->crtc_clock,
dsc ? bpp << 4 : bpp,
- dsc);
+ dsc,
+ false);
slots = drm_dp_atomic_find_time_slots(state, &intel_dp->mst_mgr,
connector->port,
@@ -983,7 +984,7 @@ intel_dp_mst_mode_valid_ctx(struct drm_connector *connector,
return ret;
if (mode_rate > max_rate || mode->clock > max_dotclk ||
- drm_dp_calc_pbn_mode(mode->clock, min_bpp, false) > port->full_pbn) {
+ drm_dp_calc_pbn_mode(mode->clock, min_bpp, false, false) > port->full_pbn) {
*status = MODE_CLOCK_HIGH;
return 0;
}
diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c b/drivers/gpu/drm/nouveau/dispnv50/disp.c
index 4e7c9c353c511..d71c28e458107 100644
--- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
+++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
@@ -967,7 +967,7 @@ nv50_msto_atomic_check(struct drm_encoder *encoder,
asyh->or.bpc = connector->display_info.bpc;
asyh->dp.pbn = drm_dp_calc_pbn_mode(clock, asyh->or.bpc * 3,
- false);
+ false, false);
}
mst_state = drm_atomic_get_mst_topology_state(state, &mstm->mgr);
diff --git a/drivers/gpu/drm/tests/drm_dp_mst_helper_test.c b/drivers/gpu/drm/tests/drm_dp_mst_helper_test.c
index ea2182815ebe8..3c0c0ffd5f9f5 100644
--- a/drivers/gpu/drm/tests/drm_dp_mst_helper_test.c
+++ b/drivers/gpu/drm/tests/drm_dp_mst_helper_test.c
@@ -16,6 +16,7 @@ struct drm_dp_mst_calc_pbn_mode_test {
const int clock;
const int bpp;
const bool dsc;
+ const bool fec;
const int expected;
};
@@ -24,39 +25,59 @@ static const struct drm_dp_mst_calc_pbn_mode_test drm_dp_mst_calc_pbn_mode_cases
.clock = 154000,
.bpp = 30,
.dsc = false,
+ .fec = false,
.expected = 689
},
{
.clock = 234000,
.bpp = 30,
.dsc = false,
+ .fec = false,
.expected = 1047
},
{
.clock = 297000,
.bpp = 24,
.dsc = false,
+ .fec = false,
.expected = 1063
},
{
.clock = 332880,
.bpp = 24 << 4,
.dsc = true,
+ .fec = false,
.expected = 1191
},
{
.clock = 324540,
.bpp = 24 << 4,
.dsc = true,
+ .fec = false,
.expected = 1161
},
+ {
+ .clock = 324540,
+ .bpp = 24 << 4,
+ .dsc = true,
+ .fec = true,
+ .expected = 1189
+ },
+ {
+ .clock = 324540,
+ .bpp = 24,
+ .dsc = false,
+ .fec = true,
+ .expected = 1189
+ },
};
static void drm_test_dp_mst_calc_pbn_mode(struct kunit *test)
{
const struct drm_dp_mst_calc_pbn_mode_test *params = test->param_value;
- KUNIT_EXPECT_EQ(test, drm_dp_calc_pbn_mode(params->clock, params->bpp, params->dsc),
+ KUNIT_EXPECT_EQ(test, drm_dp_calc_pbn_mode(params->clock, params->bpp,
+ params->dsc, params->fec),
params->expected);
}
diff --git a/include/drm/display/drm_dp_mst_helper.h b/include/drm/display/drm_dp_mst_helper.h
index ed5c9660563c4..0953b7b16a51b 100644
--- a/include/drm/display/drm_dp_mst_helper.h
+++ b/include/drm/display/drm_dp_mst_helper.h
@@ -832,7 +832,7 @@ struct edid *drm_dp_mst_get_edid(struct drm_connector *connector,
int drm_dp_get_vc_payload_bw(const struct drm_dp_mst_topology_mgr *mgr,
int link_rate, int link_lane_count);
-int drm_dp_calc_pbn_mode(int clock, int bpp, bool dsc);
+int drm_dp_calc_pbn_mode(int clock, int bpp, bool dsc, bool fec);
void drm_dp_mst_update_slots(struct drm_dp_mst_topology_state *mst_state, uint8_t link_encoding_cap);
--
2.37.2
