Hi, Michael,
thanks for looking at this.
On 6/25/21 6:02 PM, Ruhl, Michael J wrote:
-----Original Message-----
From: dri-devel <dri-devel-bounces@xxxxxxxxxxxxxxxxxxxxx> On Behalf Of
Thomas Hellström
Sent: Thursday, June 24, 2021 2:31 PM
To: intel-gfx@xxxxxxxxxxxxxxxxxxxxx; dri-devel@xxxxxxxxxxxxxxxxxxxxx
Cc: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>; Auld, Matthew
<matthew.auld@xxxxxxxxx>
Subject: [PATCH 4/4] drm/i915/gem: Migrate to system at dma-buf map time
Until we support p2p dma or as a complement to that, migrate data
to system memory at dma-buf map time if possible.
Signed-off-by: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
index 616c3a2f1baf..a52f885bc09a 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
@@ -25,7 +25,14 @@ static struct sg_table *i915_gem_map_dma_buf(struct
dma_buf_attachment *attachme
struct scatterlist *src, *dst;
int ret, i;
- ret = i915_gem_object_pin_pages_unlocked(obj);
+ ret = i915_gem_object_lock_interruptible(obj, NULL);
Hmm, I believe in most cases that the caller should be holding the
lock (object dma-resv) on this object already.
Yes, I agree, In particular for other instances of our own driver, at
least since the dma_resv introduction.
But I also think that's a pre-existing bug, since
i915_gem_object_pin_pages_unlocked() will also take the lock.
I Think we need to initially make the exporter dynamic-capable to
resolve this, and drop the locking here completely, as dma-buf docs says
that we're then guaranteed to get called with the object lock held.
I figure if we make the exporter dynamic, we need to migrate already at
dma_buf_pin time so we don't pin the object in the wrong location.
/Thomas
I know for the dynamic version of dma-buf, there is a check to make
sure that the lock is held when called.
I think you will run into some issues if you try to get it here as well.
Mike
+ if (ret)
+ return ERR_PTR(ret);
+
+ ret = i915_gem_object_migrate(obj, NULL, INTEL_REGION_SMEM);
+ if (!ret)
+ ret = i915_gem_object_pin_pages(obj);
+ i915_gem_object_unlock(obj);
if (ret)
goto err;
--
2.31.1
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