6a3552527d
Our TGL CI platforms are running into cases where aux transactions have failed to complete or declare a timeout well after the timeout limit that the hardware is supposed to enforce. From the logs it appears that these failures arise when aux transactions happen after we've entered DC6: <7> [622.523650] [drm:skl_enable_dc6 [i915]] Enabling DC6 <7> [622.523685] [drm:gen9_set_dc_state [i915]] Setting DC state from 00 to 02 ... <3> [622.535753] [drm:intel_dp_aux_xfer [i915]] *ERROR* dp aux hw did not signal timeout! <3> [622.547745] [drm:intel_dp_aux_xfer [i915]] *ERROR* dp aux hw did not signal timeout! <3> [622.559746] [drm:intel_dp_aux_xfer [i915]] *ERROR* dp aux hw did not signal timeout! <3> [622.571744] [drm:intel_dp_aux_xfer [i915]] *ERROR* dp aux hw did not signal timeout! <3> [622.583743] [drm:intel_dp_aux_xfer [i915]] *ERROR* dp aux hw did not signal timeout! <3> [622.583780] [drm:intel_dp_aux_xfer [i915]] *ERROR* dp_aux_ch not done status 0xad400bff <7> [622.863725] [drm:drm_dp_dpcd_access] Too many retries, giving up. First error: -110 On TGL AUX B & C are in PG1 (managed by the DMC firmware) rather than PG3 as they were on ICL, so allowing DC6 means the DMC firmware might shut off the power wells behind our backs when we're trying to use them. Signed-off-by: Matt Roper <matthew.d.roper@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20191025230623.27829-6-matthew.d.roper@intel.com Reviewed-by: Imre Deak <imre.deak@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.