[Intel-gfx] i915 Skylake: "Invalid ROM contents"

[Andy Lutomirski]

On Sun, Jan 10, 2016 at 11:12 AM, Andy Lutomirski <luto at amacapital.net> wrote:
> On Sun, Jan 10, 2016 at 10:41 AM, Andy Lutomirski <luto at amacapital.net> wrote:
>> On Wed, Nov 18, 2015 at 8:12 AM, Daniel Stone <daniel at fooishbar.org> wrote:
>>> Hi,
>>>
>>> On 18 November 2015 at 15:59, Andy Lutomirski <luto at amacapital.net> wrote:
>>>> On Wed, Nov 18, 2015 at 2:59 AM, Ville Syrjälä
>>>> <ville.syrjala at linux.intel.com> wrote:
>>>>> On Tue, Nov 17, 2015 at 11:43:25AM -0800, Andy Lutomirski wrote:
>>>>>> Typing:
>>>>>>
>>>>>> # cat /sys/devices/pci0000:00/0000:00:02.0/rom
>>>>>>
>>>>>> Provokes:
>>>>>>
>>>>>> i915 0000:00:02.0: Invalid ROM contents
>>>>>
>>>>> Hmm. So there's no PCI option ROM there. I wonder what is there. I
>>>>> get the same on my Braswell BTW. I tried to look through the UEFI
>>>>> spec a bit, and it seems to say that even for non-legacy option ROMs
>>>>> the 0x55aa signature should be there.
>>>>>
>>>>> But this being the GPU means we may be using the shadow ROM stuff,
>>>>> which IIRC assumes that the shadow is at 0xc000. I'm not sure that
>>>>> holds anymore with UEFI, and maybe we should be using some UEFI
>>>>> trick instead to find out where it actually lives?
>>>>>
>>>>> BTW what does 'lspci -vv -s 00:02.0' say on your machine?
>>>>>
>>>>
>>>> 00:02.0 VGA compatible controller: Intel Corporation Sky Lake
>>>> Integrated Graphics (rev 07) (prog-if 00 [VGA controller])
>>>>     DeviceName:  Onboard IGD
>>>>     Subsystem: Dell Device 0704
>>>>     Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop-
>>>> ParErr- Stepping- SERR- FastB2B- DisINTx+
>>>>     Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort-
>>>> <TAbort- <MAbort- >SERR- <PERR- INTx-
>>>>     Latency: 0
>>>>     Interrupt: pin A routed to IRQ 128
>>>>     Region 0: Memory at db000000 (64-bit, non-prefetchable) [size=16M]
>>>>     Region 2: Memory at 90000000 (64-bit, prefetchable) [size=256M]
>>>>     Region 4: I/O ports at f000 [size=64]
>>>>     Expansion ROM at <unassigned> [disabled]
>>>
>>> UEFI has an option to enable option ROMs, which is disabled by
>>> default; I wonder if having it disabled prevents all access to the
>>> ROM.
>>>
>>> Mind you, it doesn't seem to be fatal; I've not had any issues with
>>> the same machine that I can pin down to lack of ROM.
>>>
>>
>> FWIW, my logs also get spammed with:
>>
>> [  127.101881] i915 0000:00:02.0: BAR 6: [??? 0x00000000 flags 0x2]
>> has bogus alignment
>>
>> I suspect that the PCI core is just failing to recognize that the ROM
>> is disabled.
>>
>
> A bit more info:
>
> I think I only get this error when suspending for the second time
> after boot.  No clue why.
>
> I instrumented the code a bit.  At the time of that error, res->flags
> == 0x2.  It's probably not a coincidence that:
>
> #define IORESOURCE_ROM_SHADOW        (1<<1)    /* ROM is copy at C000:0 */
>
> Should pci_fixup_video check that the resource exists in the first
> place before setting flags on it?

*ping*

Hi, PCI people.

--Andy