This is a note to let you know that I've just added the patch titled
drm/amd/display: For prefetch mode > 0, extend prefetch if possible
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-amd-display-for-prefetch-mode-0-extend-prefetch-.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit b647a308d3f35a692f8d2032e9cb0b0d31d671d6
Author: Alvin Lee <alvin.lee2@xxxxxxx>
Date: Wed Dec 6 14:52:31 2023 -0500
drm/amd/display: For prefetch mode > 0, extend prefetch if possible
[ Upstream commit dd4e4bb28843393065eed279e869fac248d03f0f ]
[Description]
For mode programming we want to extend the prefetch as much as possible
(up to oto, or as long as we can for equ) if we're not already applying
the 60us prefetch requirement. This is to avoid intermittent underflow
issues during prefetch.
The prefetch extension is applied under the following scenarios:
1. We're in prefetch mode 1 (i.e. we don't support MCLK switch in blank)
2. We're using subvp or drr methods of p-state switch, in which case we
we don't care if prefetch takes up more of the blanking time
Mode programming typically chooses the smallest prefetch time possible
(i.e. highest bandwidth during prefetch) presumably to create margin between
p-states / c-states that happen in vblank and prefetch. Therefore we only
apply this prefetch extension when p-state in vblank is not required (UCLK
p-states take up the most vblank time).
Reviewed-by: Jun Lei <jun.lei@xxxxxxx>
Acked-by: Aurabindo Pillai <aurabindo.pillai@xxxxxxx>
Signed-off-by: Alvin Lee <alvin.lee2@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_32.c b/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_32.c
index cbdfb762c10c..6c84b0fa40f4 100644
--- a/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_32.c
+++ b/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_32.c
@@ -813,6 +813,8 @@ static void DISPCLKDPPCLKDCFCLKDeepSleepPrefetchParametersWatermarksAndPerforman
(v->DRAMSpeedPerState[mode_lib->vba.VoltageLevel] <= MEM_STROBE_FREQ_MHZ ||
v->DCFCLKPerState[mode_lib->vba.VoltageLevel] <= DCFCLK_FREQ_EXTRA_PREFETCH_REQ_MHZ) ?
mode_lib->vba.ip.min_prefetch_in_strobe_us : 0,
+ mode_lib->vba.PrefetchModePerState[mode_lib->vba.VoltageLevel][mode_lib->vba.maxMpcComb] > 0 || mode_lib->vba.DRAMClockChangeRequirementFinal == false,
+
/* Output */
&v->DSTXAfterScaler[k],
&v->DSTYAfterScaler[k],
@@ -3317,6 +3319,7 @@ void dml32_ModeSupportAndSystemConfigurationFull(struct display_mode_lib *mode_l
v->SwathHeightCThisState[k], v->TWait,
(v->DRAMSpeedPerState[i] <= MEM_STROBE_FREQ_MHZ || v->DCFCLKState[i][j] <= DCFCLK_FREQ_EXTRA_PREFETCH_REQ_MHZ) ?
mode_lib->vba.ip.min_prefetch_in_strobe_us : 0,
+ mode_lib->vba.PrefetchModePerState[i][j] > 0 || mode_lib->vba.DRAMClockChangeRequirementFinal == false,
/* Output */
&v->dummy_vars.dml32_ModeSupportAndSystemConfigurationFull.DSTXAfterScaler[k],
diff --git a/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c b/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c
index ecea008f19d3..208b89d13d3f 100644
--- a/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c
+++ b/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.c
@@ -3423,6 +3423,7 @@ bool dml32_CalculatePrefetchSchedule(
unsigned int SwathHeightC,
double TWait,
double TPreReq,
+ bool ExtendPrefetchIfPossible,
/* Output */
double *DSTXAfterScaler,
double *DSTYAfterScaler,
@@ -3892,12 +3893,32 @@ bool dml32_CalculatePrefetchSchedule(
/* Clamp to oto for bandwidth calculation */
LinesForPrefetchBandwidth = dst_y_prefetch_oto;
} else {
- *DestinationLinesForPrefetch = dst_y_prefetch_equ;
- TimeForFetchingMetaPTE = Tvm_equ;
- TimeForFetchingRowInVBlank = Tr0_equ;
- *PrefetchBandwidth = prefetch_bw_equ;
- /* Clamp to equ for bandwidth calculation */
- LinesForPrefetchBandwidth = dst_y_prefetch_equ;
+ /* For mode programming we want to extend the prefetch as much as possible
+ * (up to oto, or as long as we can for equ) if we're not already applying
+ * the 60us prefetch requirement. This is to avoid intermittent underflow
+ * issues during prefetch.
+ *
+ * The prefetch extension is applied under the following scenarios:
+ * 1. We're in prefetch mode > 0 (i.e. we don't support MCLK switch in blank)
+ * 2. We're using subvp or drr methods of p-state switch, in which case we
+ * we don't care if prefetch takes up more of the blanking time
+ *
+ * Mode programming typically chooses the smallest prefetch time possible
+ * (i.e. highest bandwidth during prefetch) presumably to create margin between
+ * p-states / c-states that happen in vblank and prefetch. Therefore we only
+ * apply this prefetch extension when p-state in vblank is not required (UCLK
+ * p-states take up the most vblank time).
+ */
+ if (ExtendPrefetchIfPossible && TPreReq == 0 && VStartup < MaxVStartup) {
+ MyError = true;
+ } else {
+ *DestinationLinesForPrefetch = dst_y_prefetch_equ;
+ TimeForFetchingMetaPTE = Tvm_equ;
+ TimeForFetchingRowInVBlank = Tr0_equ;
+ *PrefetchBandwidth = prefetch_bw_equ;
+ /* Clamp to equ for bandwidth calculation */
+ LinesForPrefetchBandwidth = dst_y_prefetch_equ;
+ }
}
*DestinationLinesToRequestVMInVBlank = dml_ceil(4.0 * TimeForFetchingMetaPTE / LineTime, 1.0) / 4.0;
diff --git a/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.h b/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.h
index 592d174df6c6..5d34735df83d 100644
--- a/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.h
+++ b/drivers/gpu/drm/amd/display/dc/dml/dcn32/display_mode_vba_util_32.h
@@ -747,6 +747,7 @@ bool dml32_CalculatePrefetchSchedule(
unsigned int SwathHeightC,
double TWait,
double TPreReq,
+ bool ExtendPrefetchIfPossible,
/* Output */
double *DSTXAfterScaler,
double *DSTYAfterScaler,
