linux-kernel - Re: [REGRESSION] v3.12-rc1: i915_driver

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Date:	Sun, 8 Sep 2013 11:38:47 +0200
From:	Tom Gundersen <teg@...m.no>
To:	David Herrmann <dh.herrmann@...il.com>
Cc:	"dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Daniel Vetter <daniel.vetter@...ll.ch>
Subject: Re: [REGRESSION] v3.12-rc1: i915_driver_load oopses when sysfb enabled

On Sun, Sep 8, 2013 at 2:13 AM, David Herrmann <dh.herrmann@...il.com> wrote:
> Hi
>
> On Sun, Sep 8, 2013 at 1:22 AM, Tom Gundersen <teg@...m.no> wrote:
>> Hi David,
>>
>> On Sat, Sep 7, 2013 at 11:57 PM, Tom Gundersen <teg@...m.no> wrote:
>>> On Sat, Sep 7, 2013 at 4:30 PM, David Herrmann <dh.herrmann@...il.com> wrote:
>>>> Attached are two patches. The first one should fix this issue, the
>>>> second one is the rebased ioremap_wc() patch from the other thread.
>>>>
>>>> Does this fix the issue (and the speed-problems)?
>>>
>>> Sadly, no. I added a few printk's to verify that the function you
>>> added is called (it is), but still the same oops.
>>
>> A few more datapoints:
>>
>> Triggers:
>> X86_SYSFB=y and FB_SIMPLE=n (so no fbdev until i915 is loaded)
>> X86_SYSFB=y and FB_SIMPLE=y
>>
>> Does not trigger:
>> X86_SYSFB=y, FB_EFI=yes, and without the overflow fix (i.e., so we
>> fall back to efifb)
>> X86_SYSFB=n and FB_EFI=y
>> X86_SYSFB=n and FB_EFI=n (so no fbdev until i915 is loaded)
>>
>> Does this make any sense?
>
> Thanks a lot for these results. I think I got it know. I will write a
> patch that marks the resource as busy. See:
>   kernel/resource.c iomem_map_sanity_check()
> It also contains a hint that we should set this for driver-resources
> which not directly map to hardware resources (such as veasfb and,
> obviously, simplefb).
>
> Following a diff which hopefully fixes this. The other two patches
> should still be required, though. I will try to write a proper patch
> tomorrow.
>
> Thanks a lot for these extensive tests, Tom!

No problem. Thanks for the fix, it works for me!

Cheers,

Tom

> diff --git a/arch/x86/kernel/sysfb_simplefb.c b/arch/x86/kernel/sysfb_simplefb.c
> index 22513e9..b7bb615 100644
> --- a/arch/x86/kernel/sysfb_simplefb.c
> +++ b/arch/x86/kernel/sysfb_simplefb.c
> @@ -79,7 +79,7 @@ __init int create_simplefb(const struct screen_info *si,
>
>         /* setup IORESOURCE_MEM as framebuffer memory */
>         memset(&res, 0, sizeof(res));
> -       res.flags = IORESOURCE_MEM;
> +       res.flags = IORESOURCE_MEM | IORESOURCE_BUSY;
>         res.name = simplefb_resname;
>         res.start = si->lfb_base;
>         res.end = si->lfb_base + len - 1;
--
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