Re: kern/55198: When the video card is Intel Mobile 965GMExpress,i915drmkmshaserror CPU pipe A FIFO underrun, also X freezes/hangs

["John D. Baker" <jdbaker%consolidated.net@localhost>]

The following reply was made to PR kern/55198; it has been noted by GNATS.

From: "John D. Baker" <jdbaker%consolidated.net@localhost>
To: gnats-bugs%netbsd.org@localhost
Cc: 
Subject: Re: kern/55198: When the video card is Intel Mobile
 965GMExpress,i915drmkmshaserror  CPU pipe A FIFO underrun, also X freezes/hangs
Date: Wed, 24 Jun 2020 14:32:57 -0500 (CDT)

 On Wed, 24 Jun 2020, Izumi Tsutsui wrote:
 
 > So maybe the upperlimit "gen < 050" is okay?
 
 I just re-checked my Q45 system and when using SNA it reports using the
 "EagleLake (gen 4.5)" backend, which doesn't work.  So, if the octal
 encoding accounts for fractional generation values, "gen < 050" should
 cover all the cases I can test.
 
 It should then be possible to get a working display on more intel-video
 machines w/o needing an "xorg.conf" file (important for live-CD/USB
 installs).
 
 
 Also, the "TearFree" option was defaulted to "True" some time back.
 Apparently some devices need that to produce a usable display.
 
 I find the older devices on which SNA works and those later devices
 which must revert to UXA work just fine with "TearFree" set to "False"
 (and thus save a bit of performance hit).  It would be nice to adjust
 that default in a similar fashion as the current patch does for
 "AccelMethod".
 
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