Re: [PATCH V5] i2c: designware: fix wrong Tx/Rx FIFO for ACPI

Andy Shevchenko
2016-12-15T17:57:45Z

On Wed, 2016-12-14 at 16:23 +0700, Tin Huynh wrote:
> ACPI always sets Tx/Rx FIFO to 32. This configuration will
> cause problem if the IP core supports a FIFO size of less than 32.
> The driver should read the FIFO size from the IP and select the
> smaller
> one of the two.
>
> Signed-off-by: Tin Huynh <tnhuynh@apm.com>
>

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

> ---
>  drivers/i2c/busses/i2c-designware-platdrv.c |   31
> ++++++++++++++++++++------
>  1 files changed, 24 insertions(+), 7 deletions(-)
>
> Change from V4:
>  -Change else condition and add some comments to clarify new approach.
>
> Change from V3:
>  -Use uppercase of FIFO instead of lowercase.
>  -Correct else condition when IP core return 0 of FIFO.
>
> Change from V2:
>  -Add a helper function to set FIFO size.
>
> Change from V1:
>  -Revert the default 32 for FIFO, read parameter from IP core
>  and pick the smaller one of the two.
>  -Correct the title to describe new approach.
>
> diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c
> b/drivers/i2c/busses/i2c-designware-platdrv.c
> index 0b42a12..682adc3 100644
> --- a/drivers/i2c/busses/i2c-designware-platdrv.c
> +++ b/drivers/i2c/busses/i2c-designware-platdrv.c
> @@ -150,6 +150,29 @@ static int i2c_dw_plat_prepare_clk(struct
> dw_i2c_dev *i_dev, bool prepare)
>   return 0;
>  }
>
> +static void dw_i2c_set_fifo_size(struct dw_i2c_dev *dev, int id)
> +{
> + u32 param, tx_fifo_depth, rx_fifo_depth;
> +
> + /*
> +  * Try to detect the FIFO depth if not set by interface
> driver,
> +  * the depth could be from 2 to 256 from HW spec.
> +  */
> + param = i2c_dw_read_comp_param(dev);
> + tx_fifo_depth = ((param >> 16) & 0xff) + 1;
> + rx_fifo_depth = ((param >> 8)  & 0xff) + 1;
> + if (!dev->tx_fifo_depth) {
> + dev->tx_fifo_depth = tx_fifo_depth;
> + dev->rx_fifo_depth = rx_fifo_depth;
> + dev->adapter.nr = id;
> + } else if (tx_fifo_depth >= 2) {
> + dev->tx_fifo_depth = min_t(u32, dev->tx_fifo_depth,
> + tx_fifo_depth);
> + dev->rx_fifo_depth = min_t(u32, dev->rx_fifo_depth,
> + rx_fifo_depth);
> + }
> +}
> +
>  static int dw_i2c_plat_probe(struct platform_device *pdev)
>  {
>   struct dw_i2c_platform_data *pdata = dev_get_platdata(&pdev-
> >dev);
> @@ -246,13 +269,7 @@ static int dw_i2c_plat_probe(struct
> platform_device *pdev)
>   1000000);
>   }
>
> - if (!dev->tx_fifo_depth) {
> - u32 param1 = i2c_dw_read_comp_param(dev);
> -
> - dev->tx_fifo_depth = ((param1 >> 16) & 0xff) + 1;
> - dev->rx_fifo_depth = ((param1 >> 8)  & 0xff) + 1;
> - dev->adapter.nr = pdev->id;
> - }
> + dw_i2c_set_fifo_size(dev, pdev->id);
>
>   adap = &dev->adapter;
>   adap->owner = THIS_MODULE;

--
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Intel Finland Oy