linux-kernel - [PATCH v3 1/3] drm/msm: Fix race of GPU init vs timestamp power management.

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Message-Id: <20210128210332.1690609-2-eric@anholt.net>
Date:   Thu, 28 Jan 2021 13:03:30 -0800
From:   Eric Anholt <eric@...olt.net>
To:     dri-devel@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org,
        freedreno@...ts.freedesktop.org, Rob Clark <robdclark@...il.com>,
        Sean Paul <sean@...rly.run>,
        Jordan Crouse <jcrouse@...eaurora.org>
Cc:     linux-kernel@...r.kernel.org, Eric Anholt <eric@...olt.net>
Subject: [PATCH v3 1/3] drm/msm: Fix race of GPU init vs timestamp power management.

We were using the same force-poweron bit in the two codepaths, so they
could race to have one of them lose GPU power early.

freedreno CI was seeing intermittent errors like:
[drm:_a6xx_gmu_set_oob] *ERROR* Timeout waiting for GMU OOB set GPU_SET: 0x0
and this issue could have contributed to it.

Signed-off-by: Eric Anholt <eric@...olt.net>
Fixes: 4b565ca5a2cb ("drm/msm: Add A6XX device support")
Reviewed-by: Jordan Crouse <jcrouse@...eaurora.org>
---
 drivers/gpu/drm/msm/adreno/a6xx_gmu.c | 25 ++++++++++++++++++++++---
 drivers/gpu/drm/msm/adreno/a6xx_gmu.h |  8 ++++++++
 drivers/gpu/drm/msm/adreno/a6xx_gpu.c |  4 ++--
 3 files changed, 32 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
index e6703ae98760..b3318f86aabc 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
@@ -264,6 +264,16 @@ int a6xx_gmu_set_oob(struct a6xx_gmu *gmu, enum a6xx_gmu_oob_state state)
 		}
 		name = "GPU_SET";
 		break;
+	case GMU_OOB_PERFCOUNTER_SET:
+		if (gmu->legacy) {
+			request = GMU_OOB_PERFCOUNTER_REQUEST;
+			ack = GMU_OOB_PERFCOUNTER_ACK;
+		} else {
+			request = GMU_OOB_PERFCOUNTER_REQUEST_NEW;
+			ack = GMU_OOB_PERFCOUNTER_ACK_NEW;
+		}
+		name = "PERFCOUNTER";
+		break;
 	case GMU_OOB_BOOT_SLUMBER:
 		request = GMU_OOB_BOOT_SLUMBER_REQUEST;
 		ack = GMU_OOB_BOOT_SLUMBER_ACK;
@@ -301,9 +311,14 @@ int a6xx_gmu_set_oob(struct a6xx_gmu *gmu, enum a6xx_gmu_oob_state state)
 void a6xx_gmu_clear_oob(struct a6xx_gmu *gmu, enum a6xx_gmu_oob_state state)
 {
 	if (!gmu->legacy) {
-		WARN_ON(state != GMU_OOB_GPU_SET);
-		gmu_write(gmu, REG_A6XX_GMU_HOST2GMU_INTR_SET,
-			1 << GMU_OOB_GPU_SET_CLEAR_NEW);
+		if (state == GMU_OOB_GPU_SET) {
+			gmu_write(gmu, REG_A6XX_GMU_HOST2GMU_INTR_SET,
+				1 << GMU_OOB_GPU_SET_CLEAR_NEW);
+		} else {
+			WARN_ON(state != GMU_OOB_PERFCOUNTER_SET);
+			gmu_write(gmu, REG_A6XX_GMU_HOST2GMU_INTR_SET,
+				1 << GMU_OOB_PERFCOUNTER_CLEAR_NEW);
+		}
 		return;
 	}
 
@@ -312,6 +327,10 @@ void a6xx_gmu_clear_oob(struct a6xx_gmu *gmu, enum a6xx_gmu_oob_state state)
 		gmu_write(gmu, REG_A6XX_GMU_HOST2GMU_INTR_SET,
 			1 << GMU_OOB_GPU_SET_CLEAR);
 		break;
+	case GMU_OOB_PERFCOUNTER_SET:
+		gmu_write(gmu, REG_A6XX_GMU_HOST2GMU_INTR_SET,
+			1 << GMU_OOB_PERFCOUNTER_CLEAR);
+		break;
 	case GMU_OOB_BOOT_SLUMBER:
 		gmu_write(gmu, REG_A6XX_GMU_HOST2GMU_INTR_SET,
 			1 << GMU_OOB_BOOT_SLUMBER_CLEAR);
diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gmu.h b/drivers/gpu/drm/msm/adreno/a6xx_gmu.h
index c6d2bced8e5d..9fa278de2106 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gmu.h
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gmu.h
@@ -156,6 +156,7 @@ enum a6xx_gmu_oob_state {
 	GMU_OOB_BOOT_SLUMBER = 0,
 	GMU_OOB_GPU_SET,
 	GMU_OOB_DCVS_SET,
+	GMU_OOB_PERFCOUNTER_SET,
 };
 
 /* These are the interrupt / ack bits for each OOB request that are set
@@ -190,6 +191,13 @@ enum a6xx_gmu_oob_state {
 #define GMU_OOB_GPU_SET_ACK_NEW		31
 #define GMU_OOB_GPU_SET_CLEAR_NEW	31
 
+#define GMU_OOB_PERFCOUNTER_REQUEST	17
+#define GMU_OOB_PERFCOUNTER_ACK		25
+#define GMU_OOB_PERFCOUNTER_CLEAR	25
+
+#define GMU_OOB_PERFCOUNTER_REQUEST_NEW	28
+#define GMU_OOB_PERFCOUNTER_ACK_NEW	30
+#define GMU_OOB_PERFCOUNTER_CLEAR_NEW	30
 
 void a6xx_hfi_init(struct a6xx_gmu *gmu);
 int a6xx_hfi_start(struct a6xx_gmu *gmu, int boot_state);
diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
index c8a9010c1a1d..7424a70b9d35 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
@@ -1177,12 +1177,12 @@ static int a6xx_get_timestamp(struct msm_gpu *gpu, uint64_t *value)
 	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
 
 	/* Force the GPU power on so we can read this register */
-	a6xx_gmu_set_oob(&a6xx_gpu->gmu, GMU_OOB_GPU_SET);
+	a6xx_gmu_set_oob(&a6xx_gpu->gmu, GMU_OOB_PERFCOUNTER_SET);
 
 	*value = gpu_read64(gpu, REG_A6XX_RBBM_PERFCTR_CP_0_LO,
 		REG_A6XX_RBBM_PERFCTR_CP_0_HI);
 
-	a6xx_gmu_clear_oob(&a6xx_gpu->gmu, GMU_OOB_GPU_SET);
+	a6xx_gmu_clear_oob(&a6xx_gpu->gmu, GMU_OOB_PERFCOUNTER_SET);
 	return 0;
 }
 
-- 
2.30.0