[V10,4/5] i2c: tegra: update transfer timeout

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(-)

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;
>