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a44f42ba7f
While working on supporting the Intel HDR backlight interface, I noticed that there's a couple of laptops that will very rarely manage to boot up without detecting Intel HDR backlight support - even though it's supported on the system. One example of such a laptop is the Lenovo P17 1st generation. Following some investigation Ville Syrjälä did through the docs they have available to them, they discovered that there's actually supposed to be a 30ms wait after writing the source OUI before we begin setting up the rest of the backlight interface. This seems to be correct, as adding this 30ms delay seems to have completely fixed the probing issues I was previously seeing. So - let's start performing a 30ms wait after writing the OUI, which we do in a manner similar to how we keep track of PPS delays (e.g. record the timestamp of the OUI write, and then wait for however many ms are left since that timestamp right before we interact with the backlight) in order to avoid waiting any longer then we need to. As well, this also avoids us performing this delay on systems where we don't end up using the HDR backlight interface. V3: * Move last_oui_write into intel_dp V2: * Move panel delays into intel_pps Signed-off-by: Lyude Paul <lyude@redhat.com> Reviewed-by: Jani Nikula <jani.nikula@intel.com> Fixes:4a8d79901d("drm/i915/dp: Enable Intel's HDR backlight interface (only SDR for now)") Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Cc: <stable@vger.kernel.org> # v5.12+ Signed-off-by: Jani Nikula <jani.nikula@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20211130212912.212044-1-lyude@redhat.com (cherry picked from commitc7c90b0b84) Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
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.