From 981b14f01ae79f85eae3dc6873456abd08de2d86 Mon Sep 17 00:00:00 2001 From: Stephen Warren 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 Reviewed-by: Yen Lin --- 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; -- 2.25.1