Re: kern/55198: When the video card is Intel Mobile 965GM Express,i915drmkms has error 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 965GM
 Express,i915drmkms has error CPU pipe A FIFO underrun, also X freezes/hangs
Date: Wed, 29 Apr 2020 18:49:34 -0500 (CDT)

 There was a thread about this issue in current-users some time back.  I
 don't recall if another PR was filed about it.  In that thread, X didn't
 freeze/hang but the display was corrupt/sluggish.
 
 The gist of it is, if your intel video hardware is old enough,
 
   Accelmethod "SNA"
 
 (default) works.  If it is new enough, it works, albeit "TearFree" "True"
 is required and was made default.
 
 Then there are some in the middle where Accelmethod "SNA" used to work
 (INTEL_2014 driver), but no-longer works (INTEL_2019 driver).
 
 Old enough:  i82810e (no DRMKMS), i82915, others? (Set "TearFree" "False"
 to save performance penalty.)
 
 Used to work but doesn't anymore:  i82Q45, i82G41, i82945, i82946, others.
 Must force Accelmethod "UXA" (set "TearFree" "False" to save performance
 penalty) or use the "modesetting" driver.
 
 New enough:  (See other people's messages wherein it works for them with
 "TearFree" "True".  I don't have any of these, so can't say myself.)
 
 -- 
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