linux-stable/drivers/gpu
Boris Brezillon f66ff55a9b drm/exynos: dsi: Fix bridge chain handling
Commit 05193dc381 ("drm/bridge: Make the bridge chain a double-linked
list") patched the bridge chain logic to use a double-linked list instead
of a single-linked list. This change induced changes to the Exynos driver
which was manually resetting the encoder->bridge element to NULL to
control the enable/disable sequence of the bridge chain. During this
conversion, 2 bugs were introduced:

1/ list_splice() was used to move chain elements to our own internal
   chain, but list_splice() does not reset the source list to an empty
   state, leading to unexpected bridge hook calls when
   drm_bridge_chain_xxx() helpers were called by the core. Replacing
   the list_splice() call by list_splice_init() fixes this problem.

2/ drm_bridge_chain_xxx() helpers operate on the
   bridge->encoder->bridge_chain list, which is now empty. When the
   helper uses list_for_each_entry_reverse() we end up with no operation
   done which is not what we want. But that's even worse when the helper
   uses list_for_each_entry_from(), because in that case we end up in
   an infinite loop searching for the list head element which is no
   longer encoder->bridge_chain but exynos_dsi->bridge_chain. To address
   that problem we stop using the bridge chain helpers and call the
   hooks directly.

Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Fixes: 05193dc381 ("drm/bridge: Make the bridge chain a double-linked list")
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191227144124.210294-3-boris.brezillon@collabora.com
2020-01-08 09:09:48 +01:00
..
drm drm/exynos: dsi: Fix bridge chain handling 2020-01-08 09:09:48 +01:00
host1x drm-misc-next for v5.6: 2019-12-17 13:57:54 +01:00
ipu-v3
vga vga: Fix Kconfig indentation 2019-11-20 17:40:32 +01:00
Makefile