[PATCH V5 6/7] i2c: tegra: fix PIO rx/tx residual transfer check

Bitan Biswas
2019-06-11T10:51:13Z

Fix expression for residual bytes(less than word) transfer
in I2C PIO mode RX/TX.

Signed-off-by: Bitan Biswas <bbiswas@nvidia.com>
---
drivers/i2c/busses/i2c-tegra.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
index 4dfb4c1..0596c12 100644
--- a/drivers/i2c/busses/i2c-tegra.c
+++ b/drivers/i2c/busses/i2c-tegra.c
@@ -514,7 +514,8 @@ static int tegra_i2c_empty_rx_fifo(struct tegra_i2c_dev *i2c_dev)
* If there is a partial word at the end of buf, handle it manually to
* prevent overwriting past the end of buf
*/
- if (rx_fifo_avail > 0 && buf_remaining > 0) {
+ if (rx_fifo_avail > 0 &&
+ (buf_remaining > 0 && buf_remaining < BYTES_PER_FIFO_WORD)) {
BUG_ON(buf_remaining > 3);
val = i2c_readl(i2c_dev, I2C_RX_FIFO);
val = cpu_to_le32(val);
@@ -557,11 +558,10 @@ static int tegra_i2c_fill_tx_fifo(struct tegra_i2c_dev *i2c_dev)
words_to_transfer = tx_fifo_avail;

/*
- * Update state before writing to FIFO. If this casues us
+ * Update state before writing to FIFO. If this causes us
* to finish writing all bytes (AKA buf_remaining goes to 0) we
* have a potential for an interrupt (PACKET_XFER_COMPLETE is
- * not maskable). We need to make sure that the isr sees
- * buf_remaining as 0 and doesn't call us back re-entrantly.
+ * not maskable).
*/
buf_remaining -= words_to_transfer * BYTES_PER_FIFO_WORD;
tx_fifo_avail -= words_to_transfer;
@@ -580,7 +580,8 @@ static int tegra_i2c_fill_tx_fifo(struct tegra_i2c_dev *i2c_dev)
* prevent reading past the end of buf, which could cross a page
* boundary and fault.
*/
- if (tx_fifo_avail > 0 && buf_remaining > 0) {
+ if (tx_fifo_avail > 0 &&
+ (buf_remaining > 0 && buf_remaining < BYTES_PER_FIFO_WORD)) {
BUG_ON(buf_remaining > 3);
memcpy(&val, buf, buf_remaining);
val = le32_to_cpu(val);
--
2.7.4