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830 more or less requires both pipes and DPLLs to remain on as long as either pipe is needed. However, when neither pipe is actually needed, we can save a bit of power by turning everything off. To do that we add a new "power well" that turns both pipes and DPLLs on and off in the right order. Seems to save ~50mW on my Fujitsu-Siemens Lifebook S6010. This also avoids having to abuse the load detection to force pipe A on at init time. That was never very robust, and it only worked for one pipe, whereas 830 really needs both pipes enabled. As a bonus the 830 pipe quirk is now a bit more isolated from the rest of the mode setting infrastructure, which should mean that it's much less likely someone will accidentally break it in the future. The extra cost is of course slight code duplication, but that seems like a worthwile tradeoff here. v2; s/BIT/BIT_ULL/ Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/20170601143619.27840-5-ville.syrjala@linux.intel.com Acked-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.