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

From: Jerry Snitselaar
Date: Sun Nov 10 2019 - 13:00:27 EST


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.

- default:
- return (status == TPM_STS_COMMAND_READY);
- }
+ return ((status & TPM_STS_COMMAND_READY) == TPM_STS_COMMAND_READY);
}

static irqreturn_t tis_int_handler(int dummy, void *dev_id)
--
2.7.4