linux-kernel - Re: 2.6.23-rc1-mm1 - seems OK on Dell Latitude D820, except for tpm

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Date:	Tue, 31 Jul 2007 17:31:43 -0400
From:	Valdis.Kletnieks@...edu
To:	Bjorn Helgaas <bjorn.helgaas@...com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Kylene Hall <kjhall@...ibm.com>, tpm@...horst.net,
	linux-kernel@...r.kernel.org
Subject: Re: 2.6.23-rc1-mm1 - seems OK on Dell Latitude D820, except for tpm_tis

On Tue, 31 Jul 2007 14:01:21 MDT, Bjorn Helgaas said:

> So, the BIOS is telling us that at least as currently configured, the
> TPM can't use interrupts.  /sys/devices/pnp0/00:0f/options should have
> all the *possible* TPM configurations.  I would guess that none of them
> shows an IRQ either.

Hmm.. Oddness. Looks empty:

# cat /sys/devices/pnp0/00\:0f/options | wc
      0       0       0

Or is that expected if the chipset has one cast-in-stone/ROM config?

> In general, if the BIOS says there's no interrupt, we should not poke
> around looking for one unless we think there's a BIOS defect.  I think
> you said that under 2.6.22-rc6-mm1, the TPM didn't find a working
> interrupt either.

> Yup, I hadn't considered the case of BIOS not telling us an interrupt
> for the device.  In that case, I think we should force interrupts off
> as you suggest.  Here's the patch I would propose:

Patch tested, and seems to decide to initialize in polled mode on my
machine, without having to do any /etc/modprobe.conf 'interrupts=0'.
I'm able to run the tpm_demo program from libtpm-2.0, so /dev/tpm0 does
seem to be operational.

You can stick this on the patch and pass it along:

Tested-By: <valdis.kletnieks@...edu>

but I'd suggest running a regression test against a chipset that *does*
do IRQs before sending it upstream (if you haven't already)...

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