67cc24ac17
Panel power sequence says timing T8 (time from link idle to turn on the backlight) should be at least 50 ms. This is what the .enable delay in simple-panel is for, so set it. NOTE: this overlaps with the 80 ms .prepare_to_enable delay on purpose. The data sheet says that at least 80 ms needs to pass between HPD going high and turning on the backlight and that at least 50 ms needs to pass between the link idle and the backlight going on. Thus it works like this on the system in front of me: * In bridge chip pre_enable call drm_panel_prepare() * drm_panel_prepare() -> panel_simple_prepare() * Wait for HPD GPIO to go high. * Start counting for 80 ms (store in prepared_time) * In bridge chip enable, train link then call drm_panel_enable() * drm_panel_enable() -> panel_simple_enable() * panel_simple_enable() does hardcoded 50 ms delay then enforces 80 ms from HPD going high (in case the bridge took less than 30 ms to enable / link train). * drm_panel_enable() -> backlight_enable(). Signed-off-by: Douglas Anderson <dianders@chromium.org> Signed-off-by: Linus Walleij <linus.walleij@linaro.org> Link: https://patchwork.freedesktop.org/patch/msgid/20210222081716.1.I1a45aece5d2ac6a2e73bbec50da2086e43e0862b@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.