[PATCH V3 2/3] i2c: tegra: Update transfer timeout

Sowjanya Komatineni
2019-01-26T03:58:01Z

Update I2C transfer timeout based on transfer bytes and I2C bus
rate to allow enough time during max transfer size based on the
speed.

Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
---
[V3] : Same as V2
[V2] : Added this patch in V2 series to allow enough time for data transfer
to happen.
This patch has dependency with DMA patch as TEGRA_I2C_TIMEOUT define
takes argument with this patch.

drivers/i2c/busses/i2c-tegra.c | 18 ++++++++++++++++--
1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
index aec500ef9a98..3dcbc9960d9d 100644
--- a/drivers/i2c/busses/i2c-tegra.c
+++ b/drivers/i2c/busses/i2c-tegra.c
@@ -23,7 +23,7 @@
#include <linux/reset.h>
#include <linux/slab.h>

-#define TEGRA_I2C_TIMEOUT (msecs_to_jiffies(1000))
+#define TEGRA_I2C_TIMEOUT(ms) (msecs_to_jiffies(ms))
#define BYTES_PER_FIFO_WORD 4

#define I2C_CNFG 0x000
@@ -116,6 +116,9 @@
#define I2C_MST_FIFO_STATUS_TX_MASK 0xff0000
#define I2C_MST_FIFO_STATUS_TX_SHIFT 16

+/* Packet header size in bytes */
+#define I2C_PACKET_HEADER_SIZE 12
+
/*
* msg_end_type: The bus control which need to be send at end of transfer.
* @MSG_END_STOP: Send stop pulse at end of transfer.
@@ -683,6 +686,17 @@ static int tegra_i2c_xfer_msg(struct tegra_i2c_dev *i2c_dev,
u32 int_mask;
unsigned long time_left;
unsigned long flags;
+ u16 xfer_time = 100;
+ size_t xfer_size = 0;
+
+ if (msg->flags & I2C_M_RD)
+ xfer_size = ALIGN(msg->len, BYTES_PER_FIFO_WORD);
+ else
+ xfer_size = ALIGN(msg->len, BYTES_PER_FIFO_WORD) +
+ I2C_PACKET_HEADER_SIZE;
+
+ xfer_time += DIV_ROUND_CLOSEST((xfer_size * 9) * 1000,
+ i2c_dev->bus_clk_rate);

tegra_i2c_flush_fifos(i2c_dev);

@@ -739,7 +753,7 @@ static int tegra_i2c_xfer_msg(struct tegra_i2c_dev *i2c_dev,
i2c_readl(i2c_dev, I2C_INT_MASK));

time_left = wait_for_completion_timeout(&i2c_dev->msg_complete,
- TEGRA_I2C_TIMEOUT);
+ TEGRA_I2C_TIMEOUT(xfer_time));
tegra_i2c_mask_irq(i2c_dev, int_mask);

if (time_left == 0) {
--
2.7.4