From 981b14f01ae79f85eae3dc6873456abd08de2d86 Mon Sep 17 00:00:00 2001
From: Stephen Warren <swarren@nvidia.com>
Date: Wed, 25 Jun 2014 10:57:28 -0600
Subject: [PATCH] i2c: tegra: write clean data to TX FIFO
The Tegra I2C controller's TX FIFO contains 32-bit words. If the final
FIFO entry of a transaction contains fewer than 4 bytes, the driver
currently fills the unused FIFO bytes with uninitialized data. This can
be confusing when reading back the FIFO content for debugging purposes.
Solve this by explicitly initializing the variable containing FIFO data
before filling it (partially) with data. With this change,
send_recv_packets()'s loop's if (is_write) code mirrors the else (i.e.
read) branch.
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Yen Lin <yelin@nvidia.com>
---
drivers/i2c/tegra_i2c.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/drivers/i2c/tegra_i2c.c b/drivers/i2c/tegra_i2c.c
index 97f0ca44c5..a62f30e66c 100644
--- a/drivers/i2c/tegra_i2c.c
+++ b/drivers/i2c/tegra_i2c.c
@@ -224,14 +224,16 @@ static int send_recv_packets(struct i2c_bus *i2c_bus,
if (is_write) {
/* deal with word alignment */
- if ((unsigned)dptr & 3) {
+ if ((words == 1) && last_bytes) {
+ local = 0;
+ memcpy(&local, dptr, last_bytes);
+ } else if ((unsigned)dptr & 3) {
memcpy(&local, dptr, sizeof(u32));
- writel(local, &control->tx_fifo);
- debug("pkt data sent (0x%x)\n", local);
} else {
- writel(*wptr, &control->tx_fifo);
- debug("pkt data sent (0x%x)\n", *wptr);
+ local = *wptr;
}
+ writel(local, &control->tx_fifo);
+ debug("pkt data sent (0x%x)\n", local);
if (!wait_for_tx_fifo_empty(control)) {
error = -1;
goto exit;
--
2.39.5