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* [PATCH 1/1] drm/amdgpu: Read clock counter via MMIO to reduce delay (v5)
@ 2021-07-01  9:57 YuBiao Wang
  2021-07-01 10:47 ` Christian König
                   ` (2 more replies)
  0 siblings, 3 replies; 4+ messages in thread
From: YuBiao Wang @ 2021-07-01  9:57 UTC (permalink / raw)
  To: amd-gfx
  Cc: YuBiao Wang, Andrey Grodzovsky, Jack Xiao, Feifei Xu, horace.chen,
	Kevin Wang, Tuikov Luben, Deucher Alexander, Evan Quan,
	Christian König, Monk Liu, Hawking Zhang

[Why]
GPU timing counters are read via KIQ under sriov, which will introduce
a delay.

[How]
It could be directly read by MMIO.

v2: Add additional check to prevent carryover issue.
v3: Only check for carryover for once to prevent performance issue.
v4: Add comments of the rough frequency where carryover happens.
v5: Remove mutex and gfxoff ctrl unused with current timing registers.

Signed-off-by: YuBiao Wang <YuBiao.Wang@amd.com>
Acked-by: Horace Chen <horace.chen@amd.com>
---
 drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c b/drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c
index ff7e9f49040e..5f4eae9c9526 100644
--- a/drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c
@@ -7609,10 +7609,8 @@ static int gfx_v10_0_soft_reset(void *handle)
 
 static uint64_t gfx_v10_0_get_gpu_clock_counter(struct amdgpu_device *adev)
 {
-	uint64_t clock;
+	uint64_t clock, clock_lo, clock_hi, hi_check;
 
-	amdgpu_gfx_off_ctrl(adev, false);
-	mutex_lock(&adev->gfx.gpu_clock_mutex);
 	switch (adev->asic_type) {
 	case CHIP_VANGOGH:
 	case CHIP_YELLOW_CARP:
@@ -7620,12 +7618,19 @@ static uint64_t gfx_v10_0_get_gpu_clock_counter(struct amdgpu_device *adev)
 			((uint64_t)RREG32_SOC15(SMUIO, 0, mmGOLDEN_TSC_COUNT_UPPER_Vangogh) << 32ULL);
 		break;
 	default:
-		clock = (uint64_t)RREG32_SOC15(SMUIO, 0, mmGOLDEN_TSC_COUNT_LOWER) |
-			((uint64_t)RREG32_SOC15(SMUIO, 0, mmGOLDEN_TSC_COUNT_UPPER) << 32ULL);
+		clock_hi = RREG32_SOC15_NO_KIQ(SMUIO, 0, mmGOLDEN_TSC_COUNT_UPPER);
+		clock_lo = RREG32_SOC15_NO_KIQ(SMUIO, 0, mmGOLDEN_TSC_COUNT_LOWER);
+		hi_check = RREG32_SOC15_NO_KIQ(SMUIO, 0, mmGOLDEN_TSC_COUNT_UPPER);
+		/* The GFX clock frequency is 100MHz, which sets 32-bit carry over
+		 * roughly every 42 seconds.
+		 */
+		if (hi_check != clock_hi) {
+			clock_lo = RREG32_SOC15_NO_KIQ(SMUIO, 0, mmGOLDEN_TSC_COUNT_LOWER);
+			clock_hi = hi_check;
+		}
+		clock = (uint64_t)clock_lo | ((uint64_t)clock_hi << 32ULL);
 		break;
 	}
-	mutex_unlock(&adev->gfx.gpu_clock_mutex);
-	amdgpu_gfx_off_ctrl(adev, true);
 	return clock;
 }
 
-- 
2.25.1

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^ permalink raw reply related	[flat|nested] 4+ messages in thread

end of thread, other threads:[~2021-07-01 16:39 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2021-07-01  9:57 [PATCH 1/1] drm/amdgpu: Read clock counter via MMIO to reduce delay (v5) YuBiao Wang
2021-07-01 10:47 ` Christian König
2021-07-01 10:50 ` Lazar, Lijo
2021-07-01 16:39 ` Luben Tuikov

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