[PATCH 2/4] drm/panfrost: Make reset sequence deal with an active HWPerf session

[Adrián Larumbe]

Right now, if there's a HW reset and an HWPerf session is active,
panfrost_mmu_reset() will reset mmu structs for all all open files to
have zero users and their HW address space assignment. Then, when
disabling hwperf, panfrost_mmu_as_put() will WARN that mmu->as_count is
less than zero.

Fix this by introducing a perfcnt HW reset path.

The choice was made to render perfcnt unusable after reset, so that a
user might have to reprogram it with a full disable/enable sequence
before requesting more perfcnt dumps.

Signed-off-by: Adrián Larumbe <adrian.larumbe@xxxxxxxxxxxxx>
---
 drivers/gpu/drm/panfrost/panfrost_device.c  |  1 +
 drivers/gpu/drm/panfrost/panfrost_perfcnt.c | 58 +++++++++++++++++++----------
 drivers/gpu/drm/panfrost/panfrost_perfcnt.h |  1 +
 3 files changed, 41 insertions(+), 19 deletions(-)

diff --git a/drivers/gpu/drm/panfrost/panfrost_device.c b/drivers/gpu/drm/panfrost/panfrost_device.c
index 7fed22d555a5..2a4417bc4065 100644
--- a/drivers/gpu/drm/panfrost/panfrost_device.c
+++ b/drivers/gpu/drm/panfrost/panfrost_device.c
@@ -421,6 +421,7 @@ void panfrost_device_reset(struct panfrost_device *pfdev, bool enable_job_int)
 {
 	panfrost_gpu_soft_reset(pfdev);
 
+	panfrost_perfcnt_reset(pfdev);
 	panfrost_gpu_power_on(pfdev);
 	panfrost_mmu_reset(pfdev);
 
diff --git a/drivers/gpu/drm/panfrost/panfrost_perfcnt.c b/drivers/gpu/drm/panfrost/panfrost_perfcnt.c
index 7020c0192e18..d6a6fbe35578 100644
--- a/drivers/gpu/drm/panfrost/panfrost_perfcnt.c
+++ b/drivers/gpu/drm/panfrost/panfrost_perfcnt.c
@@ -33,6 +33,7 @@ struct panfrost_perfcnt {
 	struct panfrost_file_priv *user;
 	struct mutex lock;
 	struct completion dump_comp;
+	bool hw_reset_happened;
 };
 
 void panfrost_perfcnt_clean_cache_done(struct panfrost_device *pfdev)
@@ -166,6 +167,7 @@ static int panfrost_perfcnt_enable_locked(struct panfrost_device *pfdev,
 	/* The BO ref is retained by the mapping. */
 	drm_gem_object_put(&bo->base);
 
+	perfcnt->hw_reset_happened = false;
 	perfcnt->user = user;
 
 	return 0;
@@ -183,6 +185,16 @@ static int panfrost_perfcnt_enable_locked(struct panfrost_device *pfdev,
 	return ret;
 }
 
+static void panfrost_perfcnt_gpu_disable(struct panfrost_device *pfdev)
+{
+	gpu_write(pfdev, GPU_PERFCNT_CFG,
+		  GPU_PERFCNT_CFG_MODE(GPU_PERFCNT_CFG_MODE_OFF));
+	gpu_write(pfdev, GPU_PRFCNT_JM_EN, 0x0);
+	gpu_write(pfdev, GPU_PRFCNT_SHADER_EN, 0x0);
+	gpu_write(pfdev, GPU_PRFCNT_MMU_L2_EN, 0x0);
+	gpu_write(pfdev, GPU_PRFCNT_TILER_EN, 0);
+}
+
 static int panfrost_perfcnt_disable_locked(struct panfrost_device *pfdev,
 					   struct drm_file *file_priv)
 {
@@ -193,18 +205,14 @@ static int panfrost_perfcnt_disable_locked(struct panfrost_device *pfdev,
 	if (user != perfcnt->user)
 		return -EINVAL;
 
-	gpu_write(pfdev, GPU_PRFCNT_JM_EN, 0x0);
-	gpu_write(pfdev, GPU_PRFCNT_SHADER_EN, 0x0);
-	gpu_write(pfdev, GPU_PRFCNT_MMU_L2_EN, 0x0);
-	gpu_write(pfdev, GPU_PRFCNT_TILER_EN, 0);
-	gpu_write(pfdev, GPU_PERFCNT_CFG,
-		  GPU_PERFCNT_CFG_MODE(GPU_PERFCNT_CFG_MODE_OFF));
+	panfrost_perfcnt_gpu_disable(pfdev);
 
 	perfcnt->user = NULL;
 	drm_gem_vunmap(&perfcnt->mapping->obj->base.base, &map);
 	perfcnt->buf = NULL;
 	panfrost_gem_close(&perfcnt->mapping->obj->base.base, file_priv);
-	panfrost_mmu_as_put(pfdev, perfcnt->mapping->mmu);
+	if (!perfcnt->hw_reset_happened)
+		panfrost_mmu_as_put(pfdev, perfcnt->mapping->mmu);
 	panfrost_gem_mapping_put(perfcnt->mapping);
 	perfcnt->mapping = NULL;
 	pm_runtime_put_autosuspend(pfdev->base.dev);
@@ -258,6 +266,15 @@ int panfrost_ioctl_perfcnt_dump(struct drm_device *dev, void *data,
 		goto out;
 	}
 
+	/*
+	 * A HW reset when HWPerf was active mean user should go through
+	 * a disable/enable sequence before requesting more frame dumps.
+	 */
+	if (perfcnt->hw_reset_happened) {
+		ret = -EAGAIN;
+		goto out;
+	}
+
 	ret = panfrost_perfcnt_dump_locked(pfdev);
 	if (ret)
 		goto out;
@@ -327,12 +344,7 @@ int panfrost_perfcnt_init(struct panfrost_device *pfdev)
 	perfcnt->bosize = size;
 
 	/* Start with everything disabled. */
-	gpu_write(pfdev, GPU_PERFCNT_CFG,
-		  GPU_PERFCNT_CFG_MODE(GPU_PERFCNT_CFG_MODE_OFF));
-	gpu_write(pfdev, GPU_PRFCNT_JM_EN, 0);
-	gpu_write(pfdev, GPU_PRFCNT_SHADER_EN, 0);
-	gpu_write(pfdev, GPU_PRFCNT_MMU_L2_EN, 0);
-	gpu_write(pfdev, GPU_PRFCNT_TILER_EN, 0);
+	panfrost_perfcnt_gpu_disable(pfdev);
 
 	init_completion(&perfcnt->dump_comp);
 	mutex_init(&perfcnt->lock);
@@ -344,10 +356,18 @@ int panfrost_perfcnt_init(struct panfrost_device *pfdev)
 void panfrost_perfcnt_fini(struct panfrost_device *pfdev)
 {
 	/* Disable everything before leaving. */
-	gpu_write(pfdev, GPU_PERFCNT_CFG,
-		  GPU_PERFCNT_CFG_MODE(GPU_PERFCNT_CFG_MODE_OFF));
-	gpu_write(pfdev, GPU_PRFCNT_JM_EN, 0);
-	gpu_write(pfdev, GPU_PRFCNT_SHADER_EN, 0);
-	gpu_write(pfdev, GPU_PRFCNT_MMU_L2_EN, 0);
-	gpu_write(pfdev, GPU_PRFCNT_TILER_EN, 0);
+	panfrost_perfcnt_gpu_disable(pfdev);
+}
+
+void panfrost_perfcnt_reset(struct panfrost_device *pfdev)
+{
+	struct panfrost_perfcnt *perfcnt = pfdev->perfcnt;
+
+	mutex_lock(&perfcnt->lock);
+	if (perfcnt->user) {
+		panfrost_perfcnt_gpu_disable(pfdev);
+		panfrost_mmu_as_put(pfdev, perfcnt->mapping->mmu);
+		perfcnt->hw_reset_happened = true;
+	}
+	mutex_unlock(&perfcnt->lock);
 }
diff --git a/drivers/gpu/drm/panfrost/panfrost_perfcnt.h b/drivers/gpu/drm/panfrost/panfrost_perfcnt.h
index 8bbcf5f5fb33..8b9bc704b634 100644
--- a/drivers/gpu/drm/panfrost/panfrost_perfcnt.h
+++ b/drivers/gpu/drm/panfrost/panfrost_perfcnt.h
@@ -14,5 +14,6 @@ int panfrost_ioctl_perfcnt_enable(struct drm_device *dev, void *data,
 				  struct drm_file *file_priv);
 int panfrost_ioctl_perfcnt_dump(struct drm_device *dev, void *data,
 				struct drm_file *file_priv);
+void panfrost_perfcnt_reset(struct panfrost_device *pfdev);
 
 #endif

-- 
2.53.0