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Brian Norris cc62d98bd5 Revert "drm: bridge: analogix/dp: add panel prepare/unprepare in suspend/resume time" This reverts commit `211f276ed3`. For quite some time, core DRM helpers already ensure that any relevant connectors/CRTCs/etc. are disabled, as well as their associated components (e.g., bridges) when suspending the system. Thus, analogix_dp_bridge_{enable,disable}() already get called, which in turn call drm_panel_{prepare,unprepare}(). This makes these drm_panel_() calls redundant. Besides redundancy, there are a few problems with this handling: (1) drm_panel_{prepare,unprepare}() are not* reference-counted APIs and are not in general designed to be handled by multiple callers -- although some panel drivers have a coarse 'prepared' flag that mitigates some damage, at least. So at a minimum this is redundant and confusing, but in some cases, this could be actively harmful. (2) The error-handling is a bit non-standard. We ignored errors in suspend(), but handled errors in resume(). And recently, people noticed that the clk handling is unbalanced in error paths, and getting that right is not actually trivial, given the current way errors are mostly ignored. (3) In the particular way analogix_dp_{suspend,resume}() get used (e.g., in rockchip_dp_*(), as a late/early callback), we don't necessarily have a proper PM relationship between the DP/bridge device and the panel device. So while the DP bridge gets resumed, the panel's parent device (e.g., platform_device) may still be suspended, and so any prepare() calls may fail. So remove the superfluous, possibly-harmful suspend()/resume() handling of panel state. Fixes: `211f276ed3` ("drm: bridge: analogix/dp: add panel prepare/unprepare in suspend/resume time") Link: https://lore.kernel.org/all/Yv2CPBD3Picg%2FgVe@google.com/ Signed-off-by: Brian Norris <briannorris@chromium.org> Reviewed-by: Douglas Anderson <dianders@chromium.org> Signed-off-by: Douglas Anderson <dianders@chromium.org> Link: https://patchwork.freedesktop.org/patch/msgid/20220822180729.1.I8ac5abe3a4c1c6fd5c061686c6e883c22f69022c@changeid		History 2022-09-23 07:15:18 -07:00
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README

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.