Re: Excessive WARN()s in Intel 915 driver

From: Daniel Vetter
Date: Tue Jan 07 2014 - 15:12:30 EST

On Tue, Jan 7, 2014 at 7:50 PM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> 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

> 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 -
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at