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.

Thanks,
Steve


>From dea29b2d87b7b740d3e5abad0ee72c3a01ae5b2e Mon Sep 17 00:00:00 2001
From: Stephen Douthit <steph...@silicom-usa.com>
Date: Wed, 7 Mar 2018 12:26:21 -0500
Subject: [PATCH] tpm: Don't propagate return from tis_wait_access() in
 tis_probe() if no TPM

Signed-off-by: Stephen Douthit <steph...@silicom-usa.com>
---
 src/hw/tpm_drivers.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/hw/tpm_drivers.c b/src/hw/tpm_drivers.c
index ed58bf5..9a52558 100644
--- a/src/hw/tpm_drivers.c
+++ b/src/hw/tpm_drivers.c
@@ -118,6 +118,8 @@ static u32 tis_probe(void)
 
     if ((didvid != 0) && (didvid != 0xffffffff))
         rc = 1;
+    else
+        rc = 0;
 
     /* TPM 2 has an interface register */
     u32 ifaceid = readl(TIS_REG(0, TIS_REG_IFACE_ID));
-- 
2.14.3

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