linux-kernel - RE: Linux 3.8-rc4

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <A3397C8B8B789E45844E7EC5DEAD89D02DF0AF4E@sausexdag04.amd.com>
Date:	Thu, 31 Jan 2013 16:05:23 +0000
From:	"Deucher, Alexander" <Alexander.Deucher@....com>
To:	Shuah Khan <shuahkhan@...il.com>
CC:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: RE: Linux 3.8-rc4

> -----Original Message-----
> From: Shuah Khan [mailto:shuahkhan@...il.com]
> Sent: Thursday, January 31, 2013 11:01 AM
> To: Deucher, Alexander
> Cc: Linus Torvalds; Linux Kernel Mailing List
> Subject: Re: Linux 3.8-rc4
> 
> On Thu, Jan 31, 2013 at 7:56 AM, Deucher, Alexander
> <Alexander.Deucher@....com> wrote:
> >> -----Original Message-----
> >> From: Shuah Khan [mailto:shuahkhan@...il.com]
> >> Sent: Wednesday, January 30, 2013 4:12 PM
> >> To: Deucher, Alexander
> >> Cc: Linus Torvalds; Linux Kernel Mailing List
> >> Subject: Re: Linux 3.8-rc4
> >>
> >> On Wed, Jan 30, 2013 at 8:53 AM, Deucher, Alexander
> >> <Alexander.Deucher@....com> wrote:
> >> >> -----Original Message-----
> >> >> From: Shuah Khan [mailto:shuahkhan@...il.com]
> >> >> Sent: Wednesday, January 30, 2013 10:35 AM
> >> >> To: Deucher, Alexander
> >> >> Cc: Linus Torvalds; Linux Kernel Mailing List
> >> >> Subject: Re: Linux 3.8-rc4
> >> >>
> >> >> On Wed, Jan 30, 2013 at 6:31 AM, Deucher, Alexander
> >> >> <Alexander.Deucher@....com> wrote:
> >> >>
> >> >> >>
> >> >> >> ok. I did more debugging in rv515_mc_stop() and here is what's
> >> >> >> happening. It has two display controllers and one of them is
> enabled
> >> >> >> and the other is in disabled state when AVIVO_D1CRTC_CONTROL
> is
> >> >> >> checked. The current code doesn't blank the disabled crtc.
> However, it
> >> >> >> needs to be blanked to avoid DMAR faults it appears. I think that is
> >> >> >> what the original code prior to
> >> >> >> 6253e4c75d96006c06b9ac8f417eba873de2497b commit was doing:
> >> >> >>
> >> >> >> -       WREG32(R_0060E8_D1CRTC_UPDATE_LOCK, 1);
> >> >> >> -       WREG32(R_0068E8_D2CRTC_UPDATE_LOCK, 1);
> >> >> >> -       WREG32(R_006080_D1CRTC_CONTROL, 0);
> >> >> >> -       WREG32(R_006880_D2CRTC_CONTROL, 0);
> >> >> >> -       WREG32(R_0060E8_D1CRTC_UPDATE_LOCK, 0);
> >> >> >> -       WREG32(R_0068E8_D2CRTC_UPDATE_LOCK, 0);
> >> >> >> -       WREG32(R_000330_D1VGA_CONTROL, 0);
> >> >> >> -       WREG32(R_000338_D2VGA_CONTROL, 0);
> >> >> >>
> >> >> >> Anyways, here is the diff for the change (by no means a patch) I
> made
> >> >> >> that fixed the problem:
> >> >> >
> >> >> > Unfortunately, that just fixes the problem by causing an additional
> delay
> >> >> since the wait_for_vblank() and get_frame_count() loops will timeout
> >> since
> >> >> the secondary display is disabled.  The previous code disabled the
> displays
> >> >> completely while the new code just disables the memory request
> >> interface
> >> >> so that the display timing stays on to avoid additional flicker at startup
> or
> >> GPU
> >> >> reset.  For some reason on your system there seems to be a delay in
> >> getting
> >> >> the memory request interface to stop.
> >> >> >
> >> >> > Alex
> >> >>
> >> >> Right. That makes sense and yes the annoying flicker went away. :) Can
> >> >> you think of something that can address systems that would need
> more
> >> >> time to get the memory request interface to stop such as mine?
> >> >
> >> > Does adding an additional radeon_mc_wait_for_idle(rdev) call at the
> end
> >> of rv515_mc_stop() help?  Can you find out what the minimum delay
> >> required for your system is?
> >> >
> >> > Alex
> >>
> >> Adding radeon_mc_wait_for_idle(rdev) call at the end of
> >> rv515_mc_stop() - didn't help.
> >>
> >> I tried with adding udelay() with delay values of 1,10, and 50, and
> >> 100 at the end of rv515_mc_stop(). 100 is the minimum that fixed the
> >> DMAR faults.
> >
> > I guess we can just add the delay.  I've tried all the ways I know of to get
> proper feedback from the hardware.
> >
> > Alex
> >
> 
> Do you want me to send a patch with delay()? Would you like to see the
> delay specific to this chipset which is RV620? That said if you think
> of other ideas to try instead of delay, I can continue the debug and
> testing effort.

I'm planning to merge the attached patch.  I'll let you know if I found out any other things to try.

Alex


Download attachment "0001-drm-radeon-r5xx-r7xx-wait-for-the-MC-to-settle-after.patch" of type "application/octet-stream" (1010 bytes)