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

Dmitry Osipenko
2019-01-26T18:02:12Z

26.01.2019 6:57, Sowjanya Komatineni пишет:
> Update I2C transfer timeout based on transfer bytes and I2C bus
> rate to allow enough time during max transfer size based on the
> speed.

Could it be that I2C device is busy and just slowly handling the transfer requests? Maybe better to leave the timeout as-is and assume the worst case scenario?

>
> 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;

No need to initialize xfer_size to 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) {
>