drm/bridge: analogix_dp: Support PSR-exit to disable transition

stable inclusion
from stable-v5.10.122
commit dbe04e874d4fbd56be64fdfcb29410241b6ad08a
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5W6OE

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=dbe04e874d4fbd56be64fdfcb29410241b6ad08a



--------------------------------

commit ca871659 upstream.

Most eDP panel functions only work correctly when the panel is not in
self-refresh. In particular, analogix_dp_bridge_disable() tends to hit
AUX channel errors if the panel is in self-refresh.

Given the above, it appears that so far, this driver assumes that we are
never in self-refresh when it comes time to fully disable the bridge.
Prior to commit 846c7dfc ("drm/atomic: Try to preserve the crtc
enabled state in drm_atomic_remove_fb, v2."), this tended to be true,
because we would automatically disable the pipe when framebuffers were
removed, and so we'd typically disable the bridge shortly after the last
display activity.

However, that is not guaranteed: an idle (self-refresh) display pipe may
be disabled, e.g., when switching CRTCs. We need to exit PSR first.

Stable notes: this is definitely a bugfix, and the bug has likely
existed in some form for quite a while. It may predate the "PSR helpers"
refactor, but the code looked very different before that, and it's
probably not worth rewriting the fix.

Cc: <stable@vger.kernel.org>
Fixes: 6c836d96 ("drm/rockchip: Use the helpers for PSR")
Signed-off-by: Brian Norris <briannorris@chromium.org>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20220228122522.v2.1.I161904be17ba14526f78536ccd78b85818449b51@changeid


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>
Reviewed-by: Wei Li <liwei391@huawei.com>