Thanks for an update! My comments below.
On Mon, 2016-12-12 at 15:36 +0700, Tin Huynh wrote:
> ACPI always sets txfifo and rxfifo 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.
I would use FIFO in capital to be consistent with what you refer to
(apparently not a variable name), so
Tx FIFO, Rx FIFO, FIFO, and so on.
>
> Signed-off-by: Tin Huynh <tnhuynh@xxxxxxx>
>
> ---
> drivers/i2c/busses/i2c-designware-platdrv.c | 26
> ++++++++++++++++++++------
> 1 files changed, 20 insertions(+), 6 deletions(-)
>
> 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..665f491 100644
> --- a/drivers/i2c/busses/i2c-designware-platdrv.c
> +++ b/drivers/i2c/busses/i2c-designware-platdrv.c
> @@ -150,6 +150,24 @@ 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)
> +{
> + u32 param1, tx_fifo_depth, rx_fifo_depth;
> +
> + param1 = i2c_dw_read_comp_param(dev);
You name it as param1 because you read *_PARAM1? For me it's not clear
from the name of helper function.
u32 param would work otherwise.
> + tx_fifo_depth = ((param1 >> 16) & 0xff) + 1;
> + rx_fifo_depth = ((param1 >> 8) & 0xff) + 1;
> + if (!dev->tx_fifo_depth) {
> + dev->tx_fifo_depth = tx_fifo_depth;
> + dev->rx_fifo_depth = rx_fifo_depth;
> + } else if (tx_fifo_depth) {
> + 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);
> + }
So, let's clarify here:
Is it possible to have an IP without parameter block enabled? I mean to
read something arbitrary (or zeroes, or all-ones) from param1.
If not, just remove second condition at all.
> +}
> +
> static int dw_i2c_plat_probe(struct platform_device *pdev)
> {
> struct dw_i2c_platform_data *pdata = dev_get_platdata(&pdev-
> >dev);
> @@ -246,13 +264,9 @@ 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;
>
> + if (!dev->tx_fifo_depth)
> dev->adapter.nr = pdev->id;
Now you spread condition to two locations and it's hard to remember
ordering without looking closer to the code.
That's why I suggested to pass an ID parameter in the first place.
> - }
> + dw_i2c_set_fifo_size(dev);
>
> adap = &dev->adapter;
> adap->owner = THIS_MODULE;
--
Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Intel Finland Oy
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