linux-kernel - Re: Excessive WARN()s in Intel 915 driver

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Message-ID: <CAKMK7uFEzOKYjojVop1ouRsJWyeK-rnKH-udBxZcc9fwKCOV6w@mail.gmail.com>
Date:	Tue, 7 Jan 2014 21:12:16 +0100
From:	Daniel Vetter <daniel.vetter@...ll.ch>
To:	Alan Stern <stern@...land.harvard.edu>
Cc:	intel-gfx <intel-gfx@...ts.freedesktop.org>,
	Kernel development list <linux-kernel@...r.kernel.org>
Subject: Re: Excessive WARN()s in Intel 915 driver

On Tue, Jan 7, 2014 at 7:50 PM, Alan Stern <stern@...land.harvard.edu> wrote:
> After all, it's not like there's anything I can do to fix the hardware,
> is there?  And it doesn't look like the pipe state mismatch is going to
> go away by itself.  Or is this a genuine, fixable, software bug?

These are genuine software bugs - every time one of these WARNs fires
our software tracking and the actual hardware state have diverged,
which eventually will lead to really subtle and hard to reproduce
bugs.

> In any case, wouldn't it be good enough for this message to be
> dev_warn() instead of WARN()?

I really want users to report these issues, and excessive WARNs seems
to be the only way to get those reports. Please boot with
drm.debug=0xe added to your kernel cmdline and reproduce this issues.
Also, which precise kernel are you running? Testing latest -rc is
always recommended, this state checker code is fairly new and gets
constantly extended and bugs fixed ...

Yours, Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
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