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e54a442492
It's possible to change which CRTC is in use for a given
connector/encoder/bridge while we're in self-refresh without fully
disabling the connector/encoder/bridge along the way. This can confuse
the bridge encoder/bridge, because
(a) it needs to track the SR state (trying to perform "active"
operations while the panel is still in SR can be Bad(TM)); and
(b) it tracks the SR state via the CRTC state (and after the switch, the
previous SR state is lost).
Thus, we need to either somehow carry the self-refresh state over to the
new CRTC, or else force an encoder/bridge self-refresh transition during
such a switch.
I choose the latter, so we disable the encoder (and exit PSR) before
attaching it to the new CRTC (where we can continue to assume a clean
(non-self-refresh) state).
This fixes PSR issues seen on Rockchip RK3399 systems with
drivers/gpu/drm/bridge/analogix/analogix_dp_core.c.
Change in v2:
- Drop "->enable" condition; this could possibly be "->active" to
reflect the intended hardware state, but it also is a little
over-specific. We want to make a transition through "disabled" any
time we're exiting PSR at the same time as a CRTC switch.
(Thanks Liu Ying)
Cc: Liu Ying <victor.liu@oss.nxp.com>
Cc: <stable@vger.kernel.org>
Fixes: 1452c25b0e60 ("drm: Add helpers to kick off self refresh mode in drivers")
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.v2.2.Ic15a2ef69c540aee8732703103e2cff51fb9c399@changeid
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.