[coreboot] Question about Intel HD graphics and FLR

[Joshua Pincus]

Hi Zoran,

So long as you don't have to kill anyone to get the info, I genuinely
appreciate the help.
JP

On Thu, Mar 30, 2017 at 9:54 AM, Zoran Stojsavljevic <
zoran.stojsavljevic at gmail.com> wrote:

> OK, Joshua!
>
> I do not promise anything. But I, out of (your) desperation, will try to
> find answers for you. If (no promise)...
>
> If I (eventually) return back, I have only one condition for you: NEVER
> ask how I found (any future) answer for/to you!
>
> Thank you,
> Zoran
>
> On Thu, Mar 30, 2017 at 5:48 PM, Joshua Pincus <joshua.pincus at gmail.com>
> wrote:
>
>> Hi Zoran,
>>
>> Thanks for your reply.
>>
>> My situation is this: When the VM guest comes up the first time from a
>> system-level reset (aka power on), the Broadwell HD graphics device runs
>> fine.  I see basic VGA both before and during the boot of Windows.  Once
>> Windows boots, the HD graphics device is configured by Intel's driver and I
>> see hi-rez output.  On a reboot of Windows within the VM, an FLR is
>> issued.  When the guest comes back up, no VGA.  Windows does boot but
>> provides no VGA output.  If Windows needs to drop into VGA mode so that a
>> user can access the real-mode functionality of the recovery console, still
>> no VGA.
>>
>> It's only on Broadwell-based boards that we have this problem.  If we
>> issue FLRs during the reset of the PCI bus for older Intel boards, no
>> problem.  We get VGA.  Something involved with the FLR is messing up the
>> state of the hardware instead of actually returning the hardware to a
>> virgin state, akin to what you would get from a full system reset.
>>
>> I was wondering if anyone had seen this kind of behavior.  We've tried
>> everything.  We've manipulated all of the obvious HD graphics MMIO
>> registers involved with restoring VGA but nothing seems to work.
>>
>> Thanks,
>> JP
>>
>> On Thu, Mar 30, 2017 at 4:29 AM, Zoran Stojsavljevic <
>> zoran.stojsavljevic at gmail.com> wrote:
>>
>>> Hello Joshua,
>>>
>>> I'll ask similar question, considering UEFI (BIOS). I have no idea if
>>> you can issue somehow easy FLR (PCI Function Level Reset), but if you
>>> can, does this use case repeat itself?
>>>
>>> I found, related to BIOS, this pointer (http://www.tomshardware.co.uk
>>> /forum/278002-30-solved-what-capability-option-bios), since I do NOT
>>> recall this option in any (legacy and UEFI) of the BIOSes I used (and I
>>> used lot (>100) of them). Probably, did not pay too much attention, since I
>>> do not recall this option to be tested/used?!
>>>
>>> Zoran
>>>
>>> On Wed, Mar 29, 2017 at 10:49 PM, Joshua Pincus <joshua.pincus at gmail.com
>>> > wrote:
>>>
>>>> Hi,
>>>>
>>>> After performing just an FLR (PCI function level reset) of a Gen8 Intel
>>>> HD graphics device, there's no VGA output from the device, no matter what I
>>>> try to do.  I've had coreboot reset the graphics control register, VGA
>>>> control, VGA display disable bit, etc.
>>>>
>>>> Has anyone seen anything like this?  The only way I can get VGA
>>>> restored is by performing a system-level reset.  But I just want to do an
>>>> FLR.  Any ideas?
>>>>
>>>> Thanks,
>>>> JP
>>>>
>>>> --
>>>> coreboot mailing list: coreboot at coreboot.org
>>>> https://www.coreboot.org/mailman/listinfo/coreboot
>>>>
>>>
>>>
>>
>
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