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SubjectRe: [PATCH V10 4/5] i2c: tegra: update transfer timeout
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05.02.2019 4:29, Sowjanya Komatineni пишет:
> Tegra194 allows max of 64K bytes and Tegra186 and prior allows
> max of 4K bytes of transfer per packet.
>
> one sec timeout is not enough for transfers more than 10K bytes
> at STD bus rate.
>
> This patch updates I2C transfer timeout based on the transfer size
> and I2C bus rate to allow enough time during max transfer size at
> lower bus speed.
>
> Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
> Acked-by: Thierry Reding <treding@nvidia.com>
> Reviewed-by: Dmitry Osipenko <digetx@gmail.com>
> ---
> [V10] : Reduced the timeout for bus clear operation
> Added adapter timeout to cover worst case transfer rate (max transfer
> size at STD speed) incase if ARB LOST happens during middle/end of
> the transaction.
> [V9] : Rebased to 5.0-rc4
> Minor updates for readability of xfer time
> [V8] : Added comment with explaination of xfer time calculation
> [V5/V6/V7] : Same as V4
> [V4] : V4 series includes bus clear support and this patch is updated with
> fixed timeout of 1sec for bus clear operation.
> [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 | 22 ++++++++++++++++------
> 1 file changed, 16 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
> index 658cf01e3f59..341475204cb6 100644
> --- a/drivers/i2c/busses/i2c-tegra.c
> +++ b/drivers/i2c/busses/i2c-tegra.c
> @@ -25,7 +25,6 @@
> #include <linux/pm_runtime.h>
> #include <linux/reset.h>
>
> -#define TEGRA_I2C_TIMEOUT (msecs_to_jiffies(1000))
> #define BYTES_PER_FIFO_WORD 4
>
> #define I2C_CNFG 0x000
> @@ -936,8 +935,9 @@ static int tegra_i2c_issue_bus_clear(struct tegra_i2c_dev *i2c_dev)
> i2c_writel(i2c_dev, reg, I2C_BUS_CLEAR_CNFG);
> tegra_i2c_unmask_irq(i2c_dev, I2C_INT_BUS_CLR_DONE);
>
> - time_left = wait_for_completion_timeout(&i2c_dev->msg_complete,
> - TEGRA_I2C_TIMEOUT);
> + time_left = wait_for_completion_timeout(
> + &i2c_dev->msg_complete,
> + msecs_to_jiffies(50));
> if (time_left == 0) {
> dev_err(i2c_dev->dev, "timed out for bus clear\n");
> return -ETIMEDOUT;
> @@ -964,6 +964,7 @@ static int tegra_i2c_xfer_msg(struct tegra_i2c_dev *i2c_dev,
> u32 *buffer = NULL;
> int err = 0;
> bool dma = false;
> + u16 xfer_time = 100;
>
> tegra_i2c_flush_fifos(i2c_dev);
>
> @@ -982,6 +983,13 @@ static int tegra_i2c_xfer_msg(struct tegra_i2c_dev *i2c_dev,
> dma = (xfer_size > I2C_PIO_MODE_MAX_LEN) && i2c_dev->dma_buf;
> i2c_dev->is_curr_dma_xfer = dma;
>
> + /*
> + * Transfer time in mSec = Total bits / transfer rate
> + * Total bits = 9 bits per byte (including ACK bit) + Start & stop bits
> + */
> + xfer_time += DIV_ROUND_CLOSEST(((xfer_size * 9) + 2) * MSEC_PER_SEC,
> + i2c_dev->bus_clk_rate);
> +
> spin_lock_irqsave(&i2c_dev->xfer_lock, flags);
>
> int_mask = I2C_INT_NO_ACK | I2C_INT_ARBITRATION_LOST;
> @@ -1089,7 +1097,7 @@ static int tegra_i2c_xfer_msg(struct tegra_i2c_dev *i2c_dev,
>
> time_left = wait_for_completion_timeout(
> &i2c_dev->dma_complete,
> - TEGRA_I2C_TIMEOUT);
> + msecs_to_jiffies(xfer_time));
>
> if (time_left == 0) {
> dev_err(i2c_dev->dev, "DMA transfer timeout\n");
> @@ -1110,8 +1118,9 @@ static int tegra_i2c_xfer_msg(struct tegra_i2c_dev *i2c_dev,
> }
> }
>
> - time_left = wait_for_completion_timeout(&i2c_dev->msg_complete,
> - TEGRA_I2C_TIMEOUT);
> + time_left = wait_for_completion_timeout(
> + &i2c_dev->msg_complete,
> + msecs_to_jiffies(xfer_time));
> tegra_i2c_mask_irq(i2c_dev, int_mask);
>
> if (time_left == 0) {
> @@ -1367,6 +1376,7 @@ static int tegra_i2c_probe(struct platform_device *pdev)
> i2c_dev->div_clk = div_clk;
> i2c_dev->adapter.algo = &tegra_i2c_algo;
> i2c_dev->adapter.retries = 1;
> + i2c_dev->adapter.timeout = msecs_to_jiffies(6 * MSEC_PER_SEC);

There is a "HZ" constant in kernel which is equal to a number of jiffies per second. It's a common practice to use it where appropriate, in this case it will be:

i2c_dev->adapter.timeout = 6 * HZ;

> i2c_dev->irq = irq;
> i2c_dev->cont_id = pdev->id;
> i2c_dev->dev = &pdev->dev;
>

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