Re: kern/46596 (ehci interrupt storm triggered by VGA interrupt)

[Jaromír Doleček <jaromir.dolecek%gmail.com@localhost>]

The following reply was made to PR kern/46596; it has been noted by GNATS.

From: =?UTF-8?B?SmFyb23DrXIgRG9sZcSNZWs=?= <jaromir.dolecek%gmail.com@localhost>
To: Andreas Gustafsson <gson%gson.org@localhost>
Cc: "gnats-bugs%NetBSD.org@localhost" <gnats-bugs%netbsd.org@localhost>
Subject: Re: kern/46596 (ehci interrupt storm triggered by VGA interrupt)
Date: Wed, 17 Jun 2020 11:11:45 +0200

 Can you try to disable intelfb via userconf or boot and try with that,
 to see how it behaves without the drm driver?
 
 Jaromir
 
 Le mer. 17 juin 2020 =C3=A0 11:07, Andreas Gustafsson <gson%gson.org@localhost> a =C3=
 =A9crit :
 >
 > Jaromir,
 >
 > I dug out the machine from storage and connected a VGA display using a
 > passive DVI/VGA adapter plugged into the motherboard DVI port.  My
 > test consists of starting a "vmstat 1" and unplugging/replugging the
 > adapter from the motherbord DVI port.
 >
 > I was unable to reproduce the bug using a -current USB live image, so
 > apparently it has already been fixed, and as a result, I can't
 > meaningfully test your patch.
 >
 > To narrow down the timeframe of the fix, I tried booting a couple of
 > old install CDs and breaking out of sysinst to a shell to run the
 > test.  With a 6.1.5 CD, I could reproduce the bug (the vmstat
 > interrupt column started showing 200000+ interrupts per second), but
 > with a 7.1 install CD, I could not.  Instead, the following kernel
 > message was printed:
 >
 >   drm: HPD interrupt storm detected on connector HDMI-A-1: switching from=
  hotplug detection to polling
 >
 > With the -current live image, there is neither an interrupt store nor
 > a kernel message.
 > --
 > Andreas Gustafsson, gson%gson.org@localhost