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XE_LPD brings enhanced underrun recovery: the hardware can somewhat mitigate underruns by using an interpolated replacement pixel (soft underrun) or the previous pixel (hard underrun). Furthermore, underruns can now be caused downstream by the port, even if the pipe itself is operating properly. The interrupt register and PIPE_STATUS register give us extra bits to recognize hard/soft underruns and determine whether the underrun was caused by the port, so we'll use that information to print some more descriptive errors when underruns occur. v2: - Keep ICL's PIPE_STATUS defined separately from the old GMCH pipe status register. (Ville) - Only read/clear the PIPE_STATUS register on platforms with display ver >= 11. (Lucas) v3: - Actually enable+unmask all the new underrun interrupts, clear stale bits out from PIPE_STATUS before enabling the interrupts, report all FIFO underruns errors at once, rename a bunch of stuff to unconfuse vs. PIPESTAT. (Ville) Bspec: 50335 Bspec: 50366 Cc: Lucas De Marchi <lucas.demarchi@intel.com> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Signed-off-by: Matt Roper <matthew.d.roper@intel.com> Reviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20210526000656.3060314-2-matthew.d.roper@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.