drm/panfrost: Rework page table flushing and runtime PM interaction

There is no point in resuming the h/w just to do flush operations and
doing so takes several locks which cause lockdep issues with the shrinker.
Rework the flush operations to only happen when the h/w is already awake.
This avoids taking any locks associated with resuming which trigger
lockdep warnings.

Fixes: 013b65101315 ("drm/panfrost: Add madvise and shrinker support")
Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Rob Herring <robh@kernel.org>
Acked-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190826223317.28509-5-robh@kernel.org

diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.c b/drivers/gpu/drm/panfrost/panfrost_mmu.c
index 3a8bcfa..2204e60 100644 (file)
--- a/drivers/gpu/drm/panfrost/panfrost_mmu.c
+++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c
@@ -220,6 +220,22 @@ static size_t get_pgsize(u64 addr, size_t size)
        return SZ_2M;
 }
 
+void panfrost_mmu_flush_range(struct panfrost_device *pfdev,
+                             struct panfrost_mmu *mmu,
+                             u64 iova, size_t size)
+{
+       if (mmu->as < 0)
+               return;
+
+       pm_runtime_get_noresume(pfdev->dev);
+
+       /* Flush the PTs only if we're already awake */
+       if (pm_runtime_active(pfdev->dev))
+               mmu_hw_do_operation(pfdev, mmu, iova, size, AS_COMMAND_FLUSH_PT);
+
+       pm_runtime_put_sync_autosuspend(pfdev->dev);
+}
+
 static int mmu_map_sg(struct panfrost_device *pfdev, struct panfrost_mmu *mmu,
                      u64 iova, int prot, struct sg_table *sgt)
 {
@@ -244,8 +260,7 @@ static int mmu_map_sg(struct panfrost_device *pfdev, struct panfrost_mmu *mmu,
                }
        }
 
-       mmu_hw_do_operation(pfdev, mmu, start_iova, iova - start_iova,
-                           AS_COMMAND_FLUSH_PT);
+       panfrost_mmu_flush_range(pfdev, mmu, start_iova, iova - start_iova);
 
        return 0;
 }
@@ -255,7 +270,6 @@ int panfrost_mmu_map(struct panfrost_gem_object *bo)
        struct drm_gem_object *obj = &bo->base.base;
        struct panfrost_device *pfdev = to_panfrost_device(obj->dev);
        struct sg_table *sgt;
-       int ret;
        int prot = IOMMU_READ | IOMMU_WRITE;
 
        if (WARN_ON(bo->is_mapped))
@@ -268,14 +282,7 @@ int panfrost_mmu_map(struct panfrost_gem_object *bo)
        if (WARN_ON(IS_ERR(sgt)))
                return PTR_ERR(sgt);
 
-       ret = pm_runtime_get_sync(pfdev->dev);
-       if (ret < 0)
-               return ret;
-
        mmu_map_sg(pfdev, bo->mmu, bo->node.start << PAGE_SHIFT, prot, sgt);
-
-       pm_runtime_mark_last_busy(pfdev->dev);
-       pm_runtime_put_autosuspend(pfdev->dev);
        bo->is_mapped = true;
 
        return 0;
@@ -289,17 +296,12 @@ void panfrost_mmu_unmap(struct panfrost_gem_object *bo)
        u64 iova = bo->node.start << PAGE_SHIFT;
        size_t len = bo->node.size << PAGE_SHIFT;
        size_t unmapped_len = 0;
-       int ret;
 
        if (WARN_ON(!bo->is_mapped))
                return;
 
        dev_dbg(pfdev->dev, "unmap: as=%d, iova=%llx, len=%zx", bo->mmu->as, iova, len);
 
-       ret = pm_runtime_get_sync(pfdev->dev);
-       if (ret < 0)
-               return;
-
        while (unmapped_len < len) {
                size_t unmapped_page;
                size_t pgsize = get_pgsize(iova, len - unmapped_len);
@@ -312,11 +314,7 @@ void panfrost_mmu_unmap(struct panfrost_gem_object *bo)
                unmapped_len += pgsize;
        }
 
-       mmu_hw_do_operation(pfdev, bo->mmu, bo->node.start << PAGE_SHIFT,
-                           bo->node.size << PAGE_SHIFT, AS_COMMAND_FLUSH_PT);
-
-       pm_runtime_mark_last_busy(pfdev->dev);
-       pm_runtime_put_autosuspend(pfdev->dev);
+       panfrost_mmu_flush_range(pfdev, bo->mmu, bo->node.start << PAGE_SHIFT, len);
        bo->is_mapped = false;
 }