tpm, tpm_tis: Fix timeout handling when waiting for TPM status

The change to only use interrupts to handle supported status changes
introduced an issue when it is necessary to poll for the status. Rather
than checking for the status after sleeping the code now sleeps after
the check. This means a correct, but slower, status change on the part
of the TPM can be missed, resulting in a spurious timeout error,
especially on a more loaded system. Switch back to sleeping *then*
checking. An up front check of the status has been done at the start of
the function, so this does not cause an additional delay when the status
is already what we're looking for.

Cc: stable@vger.kernel.org # v6.4+
Fixes: e87fcf0dc2b4 ("tpm, tpm_tis: Only handle supported interrupts")
Signed-off-by: Jonathan McDowell <noodles@meta.com>
Reviewed-by: Michal Suchánek <msuchanek@suse.de>
Reviewed-by: Lino Sanfilippo <l.sanfilippo@kunbus.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>

diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index fdef214b9f6bffc24017c50271e552c6e9d44564..c969a179318410905a00d710e94eeddd5c9911e4 100644 (file)
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -114,11 +114,10 @@ again:
                return 0;
        /* process status changes without irq support */
        do {
+               usleep_range(priv->timeout_min, priv->timeout_max);
                status = chip->ops->status(chip);
                if ((status & mask) == mask)
                        return 0;
-               usleep_range(priv->timeout_min,
-                            priv->timeout_max);
        } while (time_before(jiffies, stop));
        return -ETIME;
 }