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i830 seems to occasionally forget the PIPESTAT enable bits when we read the register. These aren't the only registers on i830 that have problems with RMW, as reading the double buffered plane registers returns the latched value rather than the last written value. So something similar is perhaps going on with PIPESTAT. This corruption results on vblank interrupts occasionally turning off on their own, which leads to vblank timeouts and generally a stuck display subsystem. So let's not RMW the pipestat enable bits, and instead use the cached copy we have around. Cc: Imre Deak <imre.deak@intel.com> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20170914151731.5034-1-ville.syrjala@linux.intel.com Reviewed-by: Imre Deak <imre.deak@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.