Merge tag 'docs-5.12' of git://git.lwn.net/linux

[linux-2.6-microblaze.git] / Documentation / gpu / todo.rst

diff --git a/Documentation/gpu/todo.rst b/Documentation/gpu/todo.rst
index d42c225..40ccac6 100644 (file)
--- 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
 ------------------------------------------------------------