linux-kernel - Re: [PATCH] tpm_tis: TPM_STS_DATA

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Message-Id: <1253817781.8653.3.camel@dyn531367.br.ibm.com>
Date:	Thu, 24 Sep 2009 15:43:01 -0300
From:	Rajiv Andrade <srajiv@...ux.vnet.ibm.com>
To:	Seiji Munetoh <seiji.munetoh@...il.com>
Cc:	akpm@...ux-foundation.org, Daniel Walker <dwalker@...o99.com>,
	Andy Isaacson <adi@...apodia.org>, jmorris@...ei.org,
	len.brown@...el.com, Alan Cox <alan@...rguk.ukuu.org.uk>,
	Andy Isaacson <adi@...are.com>, linux-kernel@...r.kernel.org,
	tpmdd-devel@...ts.sourceforge.net, dds@...gle.com,
	Mimi Zohar <zohar@...ux.vnet.ibm.com>,
	Shahbaz Khan <shaz.linux@...il.com>
Subject: Re: [PATCH] tpm_tis: TPM_STS_DATA_EXPECT workaround

This was already tested and, given no more comments on it, finally
reviewed. Can it already be merged?

Thanks,
Rajiv

On Sat, 2009-09-12 at 08:34 +0900, Seiji Munetoh wrote:
> On Fri, Sep 11, 2009 at 5:09 AM, Rajiv Andrade
> <srajiv@...ux.vnet.ibm.com> wrote:
> > Some newer Lenovo models are shipped with a TPM that doesn't seem to set the TPM_STS_DATA_EXPECT status bit
> > when sending it a burst of data, so the code understands it as a failure and doesn't proceed sending the chip
> > the intended data. In this patch we bypass this bit check in case the itpm module parameter was set.
> >
> > This patch is based on Andy Isaacson's one:
> >
> > http://marc.info/?l=linux-kernel&m=124650185023495&w=2
> >
> > It was heavily discussed how should we deal with identifying the chip in kernel space, but the required
> > patch to do so was NACK'd:
> >
> > http://marc.info/?l=linux-kernel&m=124650186423711&w=2
> >
> > This way we let the user choose using this workaround or not based on his
> > observations on this code behavior when trying to use the TPM.
> >
> > Fixed a checkpatch issue present on the previous patch, thanks to Daniel Walker.
> >
> > Signed-off-by: Rajiv Andrade <srajiv@...ux.vnet.ibm.com>
> 
> As far as I know, only the intel tpm has this PNP issue, so I'm fine with it.
> 
> Tested-by: Seiji Munetoh <seiji.munetoh@...il.com>
> 
> > ---
> > diff --git a/drivers/char/tpm/tpm_tis.c b/drivers/char/tpm/tpm_tis.c
> > index aec1931..c9990db 100644
> > --- a/drivers/char/tpm/tpm_tis.c
> > +++ b/drivers/char/tpm/tpm_tis.c
> > @@ -257,6 +257,10 @@ out:
> >        return size;
> >  }
> >
> > +static int itpm;
> > +module_param(itpm, bool, 0444);
> > +MODULE_PARM_DESC(itpm, "Force iTPM workarounds (found on some Lenovo laptops)");
> > +
> >  /*
> >  * If interrupts are used (signaled by an irq set in the vendor structure)
> >  * tpm.c can skip polling for the data to be available as the interrupt is
> > @@ -293,7 +297,7 @@ static int tpm_tis_send(struct tpm_chip *chip, u8 *buf, size_t len)
> >                wait_for_stat(chip, TPM_STS_VALID, chip->vendor.timeout_c,
> >                              &chip->vendor.int_queue);
> >                status = tpm_tis_status(chip);
> > -               if ((status & TPM_STS_DATA_EXPECT) == 0) {
> > +               if (!itpm && (status & TPM_STS_DATA_EXPECT) == 0) {
> >                        rc = -EIO;
> >                        goto out_err;
> >                }
> > @@ -467,6 +471,10 @@ static int tpm_tis_init(struct device *dev, resource_size_t start,
> >                 "1.2 TPM (device-id 0x%X, rev-id %d)\n",
> >                 vendor >> 16, ioread8(chip->vendor.iobase + TPM_RID(0)));
> >
> > +       if (itpm)
> > +               dev_info(dev, "Intel iTPM workaround enabled\n");
> > +
> > +
> >        /* Figure out the capabilities */
> >        intfcaps =
> >            ioread32(chip->vendor.iobase +
> >
> >
> >
> --
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