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 <[email protected]> > > --- > 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 <[email protected]> Intel Finland Oy
