[SeaBIOS] Long delay: WARNING - Timeout at wait_reg8:81! (was: [PATCH v1 0/3] tpm: Support 2.0 TPM devices connected to a TIS host)

[Paul Menzel]

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.

> 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`).


Kind regards,

Paul
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