[PATCH 3.16 065/129] tpm/tpm_i2c_atmel: Return -E2BIG when the transfer is incomplete

[Ben Hutchings]

3.16.70-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>

commit 442601e87a4769a8daba4976ec3afa5222ca211d upstream.

Return -E2BIG when the transfer is incomplete. The upper layer does
not retry, so not doing that is incorrect behaviour.

Fixes: a2871c62e186 ("tpm: Add support for Atmel I2C TPMs")
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
Reviewed-by: Stefan Berger <stefanb@xxxxxxxxxxxxx>
Reviewed-by: Jerry Snitselaar <jsnitsel@xxxxxxxxxx>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
--- a/drivers/char/tpm/tpm_i2c_atmel.c
+++ b/drivers/char/tpm/tpm_i2c_atmel.c
@@ -65,7 +65,14 @@ static int i2c_atmel_send(struct tpm_chi
 	dev_dbg(chip->dev,
 		"%s(buf=%*ph len=%0zx) -> sts=%d\n", __func__,
 		(int)min_t(size_t, 64, len), buf, len, status);
-	return status;
+	if (status < 0)
+		return status;
+
+	/* The upper layer does not support incomplete sends. */
+	if (status != len)
+		return -E2BIG;
+
+	return 0;
 }
 
 static int i2c_atmel_recv(struct tpm_chip *chip, u8 *buf, size_t count)