tpm/tpm_i2c_infineon: Add small comment about return value of __i2c_transfer

Kent Yoder indicated that the code might be a bit clearer with a comment
here, so this patch adds a small explanation of the code.

Signed-off-by: Peter Huewe <peterhuewe@gmx.de>
Signed-off-by: Kent Yoder <key@linux.vnet.ibm.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/drivers/char/tpm/tpm_i2c_infineon.c b/drivers/char/tpm/tpm_i2c_infineon.c
index d83bb8c0217b..37d5dcc10ea7 100644
--- a/drivers/char/tpm/tpm_i2c_infineon.c
+++ b/drivers/char/tpm/tpm_i2c_infineon.c
@@ -162,6 +162,10 @@ out:
         /* take care of 'guard time' */
         usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI);
 
+        /* __i2c_transfer returns the number of successfully transferred
+         * messages.
+         * So rc should be greater than 0 here otherwise we have an error.
+         */
         if (rc <= 0)
                 return -EIO;
 
@@ -208,6 +212,11 @@ static int iic_tpm_write_generic(u8 addr, u8 *buffer, size_t len,
         i2c_unlock_adapter(tpm_dev.client->adapter);
         /* take care of 'guard time' */
         usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI);
+
+        /* __i2c_transfer returns the number of successfully transferred
+         * messages.
+         * So rc should be greater than 0 here otherwise we have an error.
+         */
         if (rc <= 0)
                 return -EIO;