[SeaBIOS] Long delay: WARNING - Timeout at wait_reg8:81!

Stephen Douthit stephend at silicom-usa.com
Wed Mar 7 18:33:36 CET 2018

On 03/07/2018 10:33 AM, Paul Menzel wrote:
> Dear Stephen,
> Thank you for your quick response.
> Am Dienstag, den 06.03.2018, 11:57 -0500 schrieb Stephen Douthit:
>> On 03/06/2018 11:04 AM, Paul Menzel wrote:
>>> On 03/02/18 17:31, Kevin O'Connor wrote:
>>>> On Tue, Feb 27, 2018 at 02:17:08PM -0500, Stephen Douthit wrote:
>>> […]
>>>> Thanks.  I committed this series.
>>> The second commit introduced a regression with coreboot on the
>>> ASRock E350M1. There are a bunch of time-outs, causing the startup
>>> to be really slow. With no serial console, the user thinks, it’s
>>> not working and start to debug.
>> Looking through the the user manual for that board I don't see that it
>> has a TPM, or even the header for one, so a timeout seems correct.
> Indeed, no TPM is present.

Thanks for confirming.

>> Multiple 750ms timeouts does seem pretty painful though.  I hadn't
>> considered that tis_probe() would be called multiple times if no TPM
>> was present.
>> What's the preferred way to have a probe function run and bail before
>> rerunning the timeout?  Just put a static flag in tis_probe()?  The
>> attached patch takes that approach.  Please let me know if that fixes
>> the issue for you, or if there's some other preferred pattern I should
>> use here.
> Unfortunately, that didn’t help.
> ```
> $ git log --oneline -2
> fd1cbb4 (HEAD -> master, origin/master, origin/HEAD) tpm: Save tis_probe() result to avoid a reun of lengthy timeouts
> 5adc8bd tpm: Handle unimplemented TIS_REG_IFACE_ID in tis_get_tpm_version()
> ```
> And the time-outs seem to be around 20 seconds or more. Please find the
> log with time stamps attached (`sudo ./readserial.py /dev/ttyUSB0`).

Yikes, 20 seconds is the medium duration timeout, not the default A
timeout of 750ms.  I was poking the wrong area with the last patch.
It looks like tis_probe() is propagating the return from
tis_wait_access() in the no device present case.

Please try the attached patch instead of the 'tpm: Save tis_probe...'
and see if that works better.


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