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    SubjectRe: [PATCH] tpm_tis: TPM_STS_DATA_EXPECT workaround
    From
    On Fri, Sep 11, 2009 at 5:09 AM, Rajiv Andrade
    <srajiv@linux.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@linux.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@gmail.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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