Re: [PATCH v14 2/7] tpm: tpm_tis: Fix expected bit handling and send all bytes in one shot without last byte in exception

[Jarkko Sakkinen <jarkko@kernel.org>]

On Mon, 2021-09-13 at 17:43 +0300, amirmizi6@gmail.com wrote:
> From: Amir Mizinski <amirmizi6@gmail.com>
> 
> Detected an incorrect implementation of the send command.
> Currently, the driver polls the TPM_STS.stsValid field until TRUE; then it
> reads TPM_STS register again to verify only that TPM_STS.expect field is
> FALSE (i.e., it ignores TPM_STS.stsValid).
> Since TPM_STS.stsValid represents the TPM_STS.expect validity, both fields
> fields should be checked in the same TPM_STS register read value.
> 
> This fix modifies the signature of 'wait_for_tpm_stat()', adding an
> additional "mask_result" parameter to its call and renaming it to
> 'tpm_tis_wait_for_stat()' for better alignment with other naming.
> 'tpm_tis_wait_for_stat()' is now polling the TPM_STS with a mask and waits
> for the value in mask_result. The fix adds the ability to check if certain
> TPM_STS bits have been cleared.

Use imprative form, e.g. "Modify the signature...".

> 
> This change is also aligned to verifying the CRC on I2C TPM. The CRC
> verification should be done after the TPM_STS.expect field is cleared
> (TPM received all expected command bytes and set the calculated CRC value
> in the register).

What does it mean when you "align to verifying"?

> In addition, the send command was changed to comply with
> TCG_DesignPrinciples_TPM2p0Driver_vp24_pubrev.pdf as follows:
> - send all command bytes in one loop
> - remove special handling of the last byte
> 
> Suggested-by: Benoit Houyere <benoit.houyere@st.com>
> Signed-off-by: Amir Mizinski <amirmizi6@gmail.com>


I don't think the rename is important enough to be done, and it
definitely should not be melded into another patch.

/Jarkko