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

[Stefan Berger <stefanb@linux.ibm.com>]

On 11/10/19 1:00 PM, Jerry Snitselaar wrote:
> On Sun Nov 10 19, amirmizi6@gmail.com wrote:
>> From: Amir Mizinski <amirmizi6@gmail.com>
>>
>> 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@gmail.com>
>> ---
>> 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