From 5823cca39d585e4b4a32b1292eed0015da9c3276 Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Fri, 22 Jan 2021 14:36:23 +0100 Subject: [PATCH] drm/todo: Add entry for moving to dma_resv_lock MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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. Acked-by: Thomas Zimmermann Signed-off-by: Daniel Vetter Cc: Maarten Lankhorst Cc: Maxime Ripard Cc: Thomas Zimmermann Cc: David Airlie Cc: Daniel Vetter Cc: Sumit Semwal Cc: "Christian König" Cc: linux-media@vger.kernel.org Cc: linaro-mm-sig@lists.linaro.org Link: https://patchwork.freedesktop.org/patch/msgid/20210122133624.1751802-1-daniel.vetter@ffwll.ch --- 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 ------------------------------------------------------------