On Tue, Dec 13, 2016 at 6:25 PM, Andy Shevchenko
<andriy.shevchenko@xxxxxxxxxxxxxxx> wrote:
> On Tue, 2016-12-13 at 17:03 +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@xxxxxxx>
>>
>
> One comment below, after addressing it
>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
>
>> ---
>> drivers/i2c/busses/i2c-designware-platdrv.c | 27
>> ++++++++++++++++++++-------
>> 1 files changed, 20 insertions(+), 7 deletions(-)
>>
>> Change from V3:
>> -Use uppercase of FIFO instead of lowercase.
>> -Fix the problem 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..24032d6 100644
>> --- a/drivers/i2c/busses/i2c-designware-platdrv.c
>> +++ b/drivers/i2c/busses/i2c-designware-platdrv.c
>> @@ -150,6 +150,25 @@ 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.
> */
>
I will add your comment to the driver.
>> + 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 > 1) {
>
> This makes sense now, though I would add a comment here and use >= 2 to
> reflect datasheet.
>
> /*
> * Choose minimum values between HW and interface
> * driver provided.
> */
>
I will implement as your comment. However , because adding 1 to the
value , can i use > 2 or >=3 ?
>> + 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 +265,7 @@ 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@xxxxxxxxxxxxxxx>
> Intel Finland Oy
Thank you and regards,
Tin
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