linux-kernel - [PATCH v4 04/10] drm/panfrost: Handle error when allocating AS number

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Message-ID: <20251001022039.1215976-5-adrian.larumbe@collabora.com>
Date: Wed,  1 Oct 2025 03:20:25 +0100
From: Adrián Larumbe <adrian.larumbe@...labora.com>
To: linux-kernel@...r.kernel.org
Cc: dri-devel@...ts.freedesktop.org,
	Steven Price <steven.price@....com>,
	Boris Brezillon <boris.brezillon@...labora.com>,
	kernel@...labora.com,
	Adrián Larumbe <adrian.larumbe@...labora.com>,
	Rob Herring <robh@...nel.org>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>
Subject: [PATCH v4 04/10] drm/panfrost: Handle error when allocating AS number

If we reach the beginning of the LRU AS list, then return an error.

Reviewed-by: Boris Brezillon <boris.brezillon@...labora.com>
Signed-off-by: Adrián Larumbe <adrian.larumbe@...labora.com>
---
 drivers/gpu/drm/panfrost/panfrost_job.c     | 6 +++++-
 drivers/gpu/drm/panfrost/panfrost_mmu.c     | 5 +++--
 drivers/gpu/drm/panfrost/panfrost_mmu.h     | 2 +-
 drivers/gpu/drm/panfrost/panfrost_perfcnt.c | 9 ++++++++-
 4 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/panfrost/panfrost_job.c b/drivers/gpu/drm/panfrost/panfrost_job.c
index 3f60adc9b69d..ba934437a8ea 100644
--- a/drivers/gpu/drm/panfrost/panfrost_job.c
+++ b/drivers/gpu/drm/panfrost/panfrost_job.c
@@ -215,7 +215,11 @@ static int panfrost_job_hw_submit(struct panfrost_job *job, int js)
 		goto err_hwsubmit;
 	}
 
-	cfg = panfrost_mmu_as_get(pfdev, job->mmu);
+	ret = panfrost_mmu_as_get(pfdev, job->mmu);
+	if (ret < 0)
+		goto err_hwsubmit;
+
+	cfg = ret;
 
 	job_write(pfdev, JS_HEAD_NEXT_LO(js), lower_32_bits(jc_head));
 	job_write(pfdev, JS_HEAD_NEXT_HI(js), upper_32_bits(jc_head));
diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.c b/drivers/gpu/drm/panfrost/panfrost_mmu.c
index 1d696eeea2fa..cf272b167feb 100644
--- a/drivers/gpu/drm/panfrost/panfrost_mmu.c
+++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c
@@ -258,7 +258,7 @@ static int panfrost_mmu_cfg_init(struct panfrost_mmu *mmu,
 	}
 }
 
-u32 panfrost_mmu_as_get(struct panfrost_device *pfdev, struct panfrost_mmu *mmu)
+int panfrost_mmu_as_get(struct panfrost_device *pfdev, struct panfrost_mmu *mmu)
 {
 	int as;
 
@@ -300,7 +300,8 @@ u32 panfrost_mmu_as_get(struct panfrost_device *pfdev, struct panfrost_mmu *mmu)
 			if (!atomic_read(&lru_mmu->as_count))
 				break;
 		}
-		WARN_ON(&lru_mmu->list == &pfdev->as_lru_list);
+		if (WARN_ON(&lru_mmu->list == &pfdev->as_lru_list))
+			return -EBUSY;
 
 		list_del_init(&lru_mmu->list);
 		as = lru_mmu->as;
diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.h b/drivers/gpu/drm/panfrost/panfrost_mmu.h
index 022a9a74a114..e6e6966a0cca 100644
--- a/drivers/gpu/drm/panfrost/panfrost_mmu.h
+++ b/drivers/gpu/drm/panfrost/panfrost_mmu.h
@@ -16,7 +16,7 @@ void panfrost_mmu_fini(struct panfrost_device *pfdev);
 void panfrost_mmu_reset(struct panfrost_device *pfdev);
 void panfrost_mmu_suspend_irq(struct panfrost_device *pfdev);
 
-u32 panfrost_mmu_as_get(struct panfrost_device *pfdev, struct panfrost_mmu *mmu);
+int panfrost_mmu_as_get(struct panfrost_device *pfdev, struct panfrost_mmu *mmu);
 void panfrost_mmu_as_put(struct panfrost_device *pfdev, struct panfrost_mmu *mmu);
 
 struct panfrost_mmu *panfrost_mmu_ctx_get(struct panfrost_mmu *mmu);
diff --git a/drivers/gpu/drm/panfrost/panfrost_perfcnt.c b/drivers/gpu/drm/panfrost/panfrost_perfcnt.c
index 718eb44b40f8..a8d821e1bde2 100644
--- a/drivers/gpu/drm/panfrost/panfrost_perfcnt.c
+++ b/drivers/gpu/drm/panfrost/panfrost_perfcnt.c
@@ -132,7 +132,12 @@ static int panfrost_perfcnt_enable_locked(struct panfrost_device *pfdev,
 
 	perfcnt->user = user;
 
-	as = panfrost_mmu_as_get(pfdev, perfcnt->mapping->mmu);
+	ret = panfrost_mmu_as_get(pfdev, perfcnt->mapping->mmu);
+	if (ret < 0)
+		goto err_unsetuser;
+
+	as = ret;
+
 	cfg = GPU_PERFCNT_CFG_AS(as) |
 	      GPU_PERFCNT_CFG_MODE(GPU_PERFCNT_CFG_MODE_MANUAL);
 
@@ -166,6 +171,8 @@ static int panfrost_perfcnt_enable_locked(struct panfrost_device *pfdev,
 
 	return 0;
 
+err_unsetuser:
+	perfcnt->user = NULL;
 err_vunmap:
 	drm_gem_vunmap(&bo->base, &map);
 err_put_mapping:
-- 
2.51.0