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For certain platforms on certain encoders, timings are driven from port instead of pipe. Thus, we can't rely on pipe scanline registers to get the timing information. Some cases scanline register read will not be functional. This is causing vblank evasion logic to fail since it relies on scanline, causing atomic update failure warnings. This patch uses pipe framestamp and current timestamp registers to calculate scanline. This is an indirect way to get the scanline. It helps resolve atomic update failure for gen9 dsi platforms. v2: Addressed Ville and Daniel's review comments. Updated the register MACROs, handled race condition for register reads, extracted timings from the hwmode. Removed the dependency on crtc->config to get the encoder type. v3: Made get scanline function generic v4: Addressed Ville's review comments. Added a flag to decide timestamp based scanline reporting. Changed 64bit variables to u32 v5: Adressed Ville's review comments. Put the scanline compute function at the place of caller. Removed hwmode flags from uapi and used a local i915 data structure instead. v6: Used vblank hwmode to get the timings. v7: Fixed sparse warnings, indentation and minor review comments. v8: Limited this only for Gen9 DSI. Credits-to: Ville Syrjälä <ville.syrjala@linux.intel.com> Signed-off-by: Uma Shankar <uma.shankar@intel.com> Signed-off-by: Chandra Konduru <chandra.konduru@intel.com> Signed-off-by: Vidya Srinivas <vidya.srinivas@intel.com> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Signed-off-by: Jani Nikula <jani.nikula@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/1506347761-4201-1-git-send-email-vidya.srinivas@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.