linux-kernel - Re: [RFC] Try a bit harder to get output on the screen at panic time

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Message-ID: <1274390082.4773.1.camel@maxim-laptop>
Date:	Fri, 21 May 2010 00:14:42 +0300
From:	Maxim Levitsky <maximlevitsky@...il.com>
To:	Jesse Barnes <jbarnes@...tuousgeek.org>
Cc:	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Dave Airlie <airlied@...il.com>,
	James Simmons <jsimmons@...radead.org>
Subject: Re: [RFC] Try a bit harder to get output on the screen at panic
 time

On Thu, 2010-05-20 at 09:28 -0700, Jesse Barnes wrote: 
> On Thu, 20 May 2010 04:27:07 +0300
> Maxim Levitsky <maximlevitsky@...il.com> wrote:
> 
> > On Thu, 2010-05-20 at 04:13 +0300, Maxim Levitsky wrote: 
> > > On Wed, 2010-05-19 at 17:34 -0700, Jesse Barnes wrote: 
> > > > On Fri, 9 Apr 2010 15:10:50 -0700
> > > > Jesse Barnes <jbarnes@...tuousgeek.org> wrote:
> > > > 
> > > > > This set of 3 patches makes it a little more likely we'll get panic
> > > > > output onto the screen even when X is running, assuming a KMS enabled
> > > > > stack anyway.
> > > > > 
> > > > > It gets me from a blank or very sparsely populated black screen at
> > > > > panic time, to one including the full backtrace and panic output at
> > > > > panic time (tested with "echo c > /proc/sysrq-trigger" from an X
> > > > > session).
> > > > > 
> > > > > It doesn't cover every case; for instance I think it'll fail when X has
> > > > > disabled the display, but those cases need to be handled with separate
> > > > > patches anyway (need to add atomic DPMS paths for instance).
> > > > > 
> > > > > Anyway, please test these out and let me know if they work for you.
> > > > 
> > > > Ping Linus & Dave again.  Have you guys tried these?  Really, it's cool.
> > > > 
> > > Second that, just tested these patches, and these work perfectly.
> > > One more reason for me to dump nvidia driver for nouveau.
> > 
> > 
> > Unfortunately I spoke too soon.
> > 
> > 
> > After suspend to ram, system doesn't properly resume now.
> > 
> > My system is based on nvidia G86, I use latest nouveau drivers, and
> > suspend with compiz running.
> > 
> > I also patched kernel not to do vt switch on suspend/resume:
> > 
> > diff --git a/drivers/gpu/drm/nouveau/nouveau_state.c
> > b/drivers/gpu/drm/nouveau/nouveau_state.c
> > index 062b7f6..b3ef08b 100644
> > --- a/drivers/gpu/drm/nouveau/nouveau_state.c
> > +++ b/drivers/gpu/drm/nouveau/nouveau_state.c
> > @@ -31,6 +31,7 @@
> > #include "drm_crtc_helper.h"
> > #include <linux/vgaarb.h>
> > #include <linux/vga_switcheroo.h>
> > +#include <linux/suspend.h>
> > 
> > #include "nouveau_drv.h"
> > #include "nouveau_drm.h"
> > @@ -771,6 +772,8 @@ int nouveau_load(struct drm_device *dev, unsigned
> > long flags)
> >                 int ret = nouveau_card_init(dev);
> >                 if (ret)
> >                         return ret;
> > +
> > +               pm_set_vt_switch(0);
> >         }
> > 
> >         return 0;
> 
> Hm I don't see how my patches would have affected suspend/resume, since
> they just add "oops_in_progress" checks to a few places.  Are you sure
> something else isn't breaking your resume path?
I am sure. I just reverted them, and everything works again.
I refer to 3 patches in this thread.

Best regards,
Maxim Levitsky


> 


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