On Wed, Oct 14, 2026 at 10:34:42AM -0700, Niranjana Vishwanathapura wrote:
On Wed, Oct 14, 2026 at 09:31:00AM +0200, Thomas Zimmermann wrote:
Hi
Am 13.10.26 um 20:29 schrieb Niranjana Vishwanathapura:
On Tue, Oct 13, 2026 at 09:17:17AM +0200, Thomas Zimmermann wrote:
Hi,
I don't think we should merge this series.
Testing for the functions struct is a hack, which we do because
it works in practice. We don't any other good identifier for the
source of the imported dma_buf. We want to hide this from the
outside world as much as possible. Putting it into an exported
interface goes in the wrong direction.
Ok, I understand. Given it is just a utility function that is helpful
across drivers, would defining drm_gem_prime_self_import() as a static
inline helper in drm_prime.h is permissible?
It's not about the EXPORT_SYMBOL. Please see my reply to Matthew for
details.
I think it would be OK to do something like this in the header file:
static inline bool __drm_gem_is_exported_dma_buf(dev, ops, dma_buf)
{
/* do the prime test here, but with the given ops. */
}
Double-underscore prefix in symbols means 'implementation detail'.
The existing drm_gem_is_prime_exported_dma_buf() can be implemented
on top; existing callers should continue to use
drm_gem_prime_eported_dma_buf(). Other drivers can use the new
helper for the test, as they use the same logic internally.
drm_gem_is_prime_exported_dma_buf() do not take object reference.
The code duplicated in multliple drivers take object reference. So, we
need the helper routine to take object reference.
I posted a newer series by moving drm_gem_prime_self_import() to the
drm_gem.h function.
And though using dma_buf_ops here is a plumbing due to lack of proper
driver identifier, idea is to have the drivers use this helper routine.
So, instead of a '__' naming prefix, I have added an explicit comment
about it in function kernel-doc.
Niranjana
Niranjana
Best regards
Thomas
Niranjana
Best regards
Thomas
Am 13.10.26 um 03:06 schrieb Niranjana Vishwanathapura:
Detecting that a PRIME dma-buf being imported was exported by the same
DRM device is a pattern currently open-coded in many drivers (compare
dma_buf->ops against the driver's own ops, check obj->dev == dev, then
return the GEM object with an extra reference). This series
adds generic
helpers for it and converts several drivers to use them.
Patch 1 adds drm_gem_prime_self_import(dev, dma_buf, ops): for
a dma-buf
self-exported via the given ops, it returns the backing GEM object with
a reference, letting a driver short-circuit the generic PRIME
import and
skip the extra dma-buf file reference. Patch 2 converts Xe to it.
Patch 3 adds drm_gem_prime_dma_buf_to_gem(), a thin wrapper
that uses the
core PRIME ops, and replaces the
drm_gem_is_prime_exported_dma_buf() bool
predicate with it so the shmem importer resolves the object directly
(the sole caller already wanted the referenced object).
Patches 4-6 convert panthor, panfrost and amdgpu to
drm_gem_prime_self_import(), removing the duplicated open-coded checks.
No intended functional change.
Assisted-by: GitHub-Copilot:claude-opus-4.8
Signed-off-by: Niranjana Vishwanathapura
<[email protected]>
Farah Kassabri (2):
drm/gem: add helper to detect self-imported PRIME dma-bufs
drm/xe/dma-buf: Use drm helper to detect dma-buf self-import
Niranjana Vishwanathapura (4):
drm/gem: add drm_gem_prime_dma_buf_to_gem() self-import helper
drm/panthor: use drm_gem_prime_self_import() helper
drm/panfrost: use drm_gem_prime_self_import() helper
drm/amdgpu: use drm_gem_prime_self_import() helper
drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c | 14 +---
drivers/gpu/drm/drm_gem_shmem_helper.c | 14 ++--
drivers/gpu/drm/drm_prime.c | 74 +++++++++++++++------
drivers/gpu/drm/panfrost/panfrost_gem.c | 10 +--
drivers/gpu/drm/panthor/panthor_gem.c | 10 +--
drivers/gpu/drm/xe/xe_dma_buf.c | 23 ++++---
drivers/gpu/drm/xe/xe_dma_buf.h | 2 +
include/drm/drm_prime.h | 8 ++-
8 files changed, 91 insertions(+), 64 deletions(-)
--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Stefan Gaiser, Jochen Jaser, Abhinav Puri, (HRB 36809, AG Nürnberg)
--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Stefan Gaiser, Jochen Jaser, Abhinav Puri, (HRB 36809, AG Nürnberg)
