On Fri, Jan 22, 2021 at 03:06:44PM +0100, Thomas Zimmermann wrote:

Hi

Am 22.01.21 um 14:36 schrieb Daniel Vetter:

...

Requested by Thomas. I think it justifies a new level, since I tried to make some forward progress on this last summer, and gave up (for now). This is very tricky.

Adding it to the TODO list is a first step. :)

Acked-by: Thomas Zimmermann tzimmermann@suse.de

Applied. -Daniel

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Signed-off-by: Daniel Vetter daniel.vetter@intel.com Cc: Maarten Lankhorst maarten.lankhorst@linux.intel.com Cc: Maxime Ripard mripard@kernel.org Cc: Thomas Zimmermann tzimmermann@suse.de Cc: David Airlie airlied@linux.ie Cc: Daniel Vetter daniel@ffwll.ch Cc: Sumit Semwal sumit.semwal@linaro.org Cc: "Christian König" christian.koenig@amd.com Cc: linux-media@vger.kernel.org Cc: linaro-mm-sig@lists.linaro.org

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Documentation/gpu/todo.rst | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+)

diff --git a/Documentation/gpu/todo.rst b/Documentation/gpu/todo.rst index dea9082c0e5f..f872d3d33218 100644 --- a/Documentation/gpu/todo.rst +++ b/Documentation/gpu/todo.rst @@ -23,6 +23,9 @@ Advanced: Tricky tasks that need fairly good understanding of the DRM subsystem and graphics topics. Generally need the relevant hardware for development and testing. +Expert: Only attempt these if you've successfully completed some tricky +refactorings already and are an expert in the specific area

• Subsystem-wide refactorings

@@ -168,6 +171,22 @@ Contact: Daniel Vetter, respective driver maintainers Level: Advanced +Move Buffer Object Locking to dma_resv_lock() +---------------------------------------------

+Many drivers have their own per-object locking scheme, usually using +mutex_lock(). This causes all kinds of trouble for buffer sharing, since +depending which driver is the exporter and importer, the locking hierarchy is +reversed.

+To solve this we need one standard per-object locking mechanism, which is +dma_resv_lock(). This lock needs to be called as the outermost lock, with all +other driver specific per-object locks removed. The problem is tha rolling out +the actual change to the locking contract is a flag day, due to struct dma_buf +buffer sharing.

+Level: Expert

• Convert logging to drm_* functions with drm_device paramater

-- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Felix Imendörffer