[PATCH 3/9] drm/panfrost: handle error when allocating AS number

[Adrián Larumbe]

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

Signed-off-by: Adrián Larumbe <adrian.laru...@collabora.com>
---
 drivers/gpu/drm/panfrost/panfrost_job.c     | 4 +++-
 drivers/gpu/drm/panfrost/panfrost_mmu.c     | 8 +++++---
 drivers/gpu/drm/panfrost/panfrost_mmu.h     | 2 +-
 drivers/gpu/drm/panfrost/panfrost_perfcnt.c | 5 ++++-
 4 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/panfrost/panfrost_job.c 
b/drivers/gpu/drm/panfrost/panfrost_job.c
index f640d211cc3a..f0a4690bcdf9 100644
--- a/drivers/gpu/drm/panfrost/panfrost_job.c
+++ b/drivers/gpu/drm/panfrost/panfrost_job.c
@@ -213,7 +213,9 @@ static void panfrost_job_hw_submit(struct panfrost_job 
*job, int js)
                return;
        }
 
-       cfg = panfrost_mmu_as_get(pfdev, job->mmu);
+       ret = panfrost_mmu_as_get(pfdev, job->mmu, &cfg);
+       if (ret)
+               return;
 
        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 2189e42d2bfa..8514a02d306d 100644
--- a/drivers/gpu/drm/panfrost/panfrost_mmu.c
+++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c
@@ -155,7 +155,7 @@ static void panfrost_mmu_disable(struct panfrost_device 
*pfdev, u32 as_nr)
        write_cmd(pfdev, as_nr, AS_COMMAND_UPDATE);
 }
 
-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, u32 *asi)
 {
        int as;
 
@@ -197,7 +197,8 @@ 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 -1;
 
                list_del_init(&lru_mmu->list);
                as = lru_mmu->as;
@@ -220,7 +221,8 @@ u32 panfrost_mmu_as_get(struct panfrost_device *pfdev, 
struct panfrost_mmu *mmu)
 
 out:
        spin_unlock(&pfdev->as_lock);
-       return as;
+       *asi = as;
+       return 0;
 }
 
 void panfrost_mmu_as_put(struct panfrost_device *pfdev, struct panfrost_mmu 
*mmu)
diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.h 
b/drivers/gpu/drm/panfrost/panfrost_mmu.h
index 022a9a74a114..0b2c0b59db3f 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, u32 *asi);
 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 f30817bcf8ba..d3436240f847 100644
--- a/drivers/gpu/drm/panfrost/panfrost_perfcnt.c
+++ b/drivers/gpu/drm/panfrost/panfrost_perfcnt.c
@@ -130,7 +130,10 @@ 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, &as);
+       if (ret)
+               return -EBUSY;
+
        cfg = GPU_PERFCNT_CFG_AS(as) |
              GPU_PERFCNT_CFG_MODE(GPU_PERFCNT_CFG_MODE_MANUAL);
 
-- 
2.46.2