On Thu, Oct 20, 2022 at 5:13 AM Christian König ckoenig.leichtzumerken@gmail.com wrote:
When a device driver is snooping the CPU cache during access we assume that all importers need to be able to snoop the CPU cache as well.
Signed-off-by: Christian König christian.koenig@amd.com
drivers/gpu/drm/drm_prime.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c index 20e109a802ae..d5c70b6fe8a4 100644 --- a/drivers/gpu/drm/drm_prime.c +++ b/drivers/gpu/drm/drm_prime.c @@ -28,6 +28,7 @@
#include <linux/export.h> #include <linux/dma-buf.h> +#include <linux/dma-map-ops.h> #include <linux/rbtree.h> #include <linux/module.h>
@@ -889,6 +890,7 @@ struct dma_buf *drm_gem_prime_export(struct drm_gem_object *obj, .size = obj->size, .flags = flags, .priv = obj,
.coherent = dev_is_dma_coherent(dev->dev),
To set the coherent flag correctly, I think I'd need a way to override on a per buffer basis, since coherency is a property of the gpu pgtables (which in the msm case is an immutable property of the gem object). We also have some awkwardness that drm->dev isn't actually the GPU, thanks to the kernels device model seeing a collection of other small devices shoehorned into a single drm device to fit userspace's view of the world. So relying on drm->dev isn't really going to give sensible results.
I guess msm could just bury our heads in the sand and continue to do things the way we have been (buffers that are mapped cached-coherent are only self-shared) but would be nice to catch if userspace tried to import one into (for ex) v4l2..
BR, -R
.resv = obj->resv, };-- 2.25.1