Imre Deak 1f1be49fb6 drm/i915: Avoid HPD poll detect triggering a new detect cycle
For the HPD interrupt functionality the HW depends on power wells in the
display core domain to be on. Accordingly when enabling these power
wells the HPD polling logic will force an HPD detection cycle to account
for hotplug events that may have happened when such a power well was
off.

Thus a detect cycle started by polling could start a new detect cycle if
a power well in the display core domain gets enabled during detect and
stays enabled after detect completes. That in turn can lead to a
detection cycle runaway.

To prevent re-triggering a poll-detect cycle make sure we drop all power
references we acquired during detect synchronously by the end of detect.
This will let the poll-detect logic continue with polling (matching the
off state of the corresponding power wells) instead of scheduling a new
detection cycle.

Fixes: 6cfe7ec02e85 ("drm/i915: Remove the unneeded AUX power ref from intel_dp_detect()")
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=112125
Reported-and-tested-by: Val Kulkov <val.kulkov@gmail.com>
Reported-and-tested-by: wangqr <wqr.prg@gmail.com>
Cc: Val Kulkov <val.kulkov@gmail.com>
Cc: wangqr <wqr.prg@gmail.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191028181517.22602-1-imre.deak@intel.com
(cherry picked from commit a8ddac7c9f06a12227a4f5febd1cbe0575a33179)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
2019-11-04 13:24:11 -08:00
2019-11-02 11:08:19 -07:00
2019-11-02 14:34:00 -07:00
2019-10-25 16:11:55 -04:00
2019-11-03 08:25:25 -08:00
2019-09-22 10:34:46 -07:00
2019-10-26 19:43:12 -04:00
2019-11-03 14:07:26 -08:00

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.
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