Re: [PATCH v1 3/5] char: tpm: rewrite "tpm_tis_req_canceled()"

[Stefan Berger]

On 11/10/19 1:00 PM, Jerry Snitselaar wrote:
> On Sun Nov 10 19, amirmizi6@xxxxxxxxx wrote:
> > From: Amir Mizinski <amirmizi6@xxxxxxxxx>
> >
> > using this function while read/write data resulted in aborted operation.
> > after investigating according to TCG TPM Profile (PTP) Specifications,
> > i found cancel should happen only if TPM_STS.commandReady bit is lit
> > and couldn't find a case when the current condition is valid.
> > also only cmdReady bit need to be compared instead of the full lower 
> > status register byte.
> >
> > Signed-off-by: Amir Mizinski <amirmizi6@xxxxxxxxx>
> > ---
> > drivers/char/tpm/tpm_tis_core.c | 12 +-----------
> > 1 file changed, 1 insertion(+), 11 deletions(-)
> >
> > diff --git a/drivers/char/tpm/tpm_tis_core.c 
> > b/drivers/char/tpm/tpm_tis_core.c
> > index ce7f8a1..9016f06 100644
> > --- a/drivers/char/tpm/tpm_tis_core.c
> > +++ b/drivers/char/tpm/tpm_tis_core.c
> > @@ -627,17 +627,7 @@ static int probe_itpm(struct tpm_chip *chip)
> >
> > static bool tpm_tis_req_canceled(struct tpm_chip *chip, u8 status)
> > {
> > -    struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
> > -
> > -    switch (priv->manufacturer_id) {
> > -    case TPM_VID_WINBOND:
> > -        return ((status == TPM_STS_VALID) ||
> > -            (status == (TPM_STS_VALID | TPM_STS_COMMAND_READY)));
> > -    case TPM_VID_STM:
> > -        return (status == (TPM_STS_VALID | TPM_STS_COMMAND_READY));
>
> Stefan were these cases you found that were deviating from the spec? 
> Wondering
> if dropping these will cause issues for these devices.


I believe these devices needed special handling of the status register 
as they didn't behave as the 'other' devices, so I would expect issues.

   Stefan