On Tue, Aug 19, 2014 at 09:18:49PM +0100, atull@xxxxxxxxxxxxxxxxxxxxx wrote:
> From: Alan Tull <atull@xxxxxxxxxxxxxxxxxxxxx>
>
> Use the documented, but unimplemented "clock-frequency"
> Device Tree setting as a guide on whether to set the speed
> mode bits in DW_IC_CON to standard or fast i2c mode.
>
> Previously, the driver was hardwired to fast mode. Default
> to fast mode if the "clock-frequency" property is not present
> for backwards compatiblity.
>
> Signed-off-by: Alan Tull <atull@xxxxxxxxxxxxxxxxxxxxx>
> ---
> drivers/i2c/busses/i2c-designware-platdrv.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
> index bc87733..18cd3d9 100644
> --- a/drivers/i2c/busses/i2c-designware-platdrv.c
> +++ b/drivers/i2c/busses/i2c-designware-platdrv.c
> @@ -122,7 +122,8 @@ static int dw_i2c_probe(struct platform_device *pdev)
> struct dw_i2c_dev *dev;
> struct i2c_adapter *adap;
> struct resource *mem;
> - int irq, r;
> + int irq, r, ret, speed = DW_IC_CON_SPEED_FAST;
> + u32 bus_rate;
>
> irq = platform_get_irq(pdev, 0);
> if (irq < 0) {
> @@ -167,6 +168,11 @@ static int dw_i2c_probe(struct platform_device *pdev)
> of_property_read_u32(pdev->dev.of_node,
> "i2c-scl-falling-time-ns",
> &dev->scl_falling_time);
> +
> + ret = of_property_read_u32(pdev->dev.of_node,
> + "clock-frequency", &bus_rate);
> + if (!ret && (bus_rate <= 100000))
> + speed = DW_IC_CON_SPEED_STD;
This looks a bit odd.
If the device only supports two particular speeds why do we accept any
other speed in the clock-frequency property? Surely we should at least
warn that something was off?
Thanks,
Mark
> }
>
> dev->functionality =
> @@ -177,7 +183,7 @@ static int dw_i2c_probe(struct platform_device *pdev)
> I2C_FUNC_SMBUS_WORD_DATA |
> I2C_FUNC_SMBUS_I2C_BLOCK;
> dev->master_cfg = DW_IC_CON_MASTER | DW_IC_CON_SLAVE_DISABLE |
> - DW_IC_CON_RESTART_EN | DW_IC_CON_SPEED_FAST;
> + DW_IC_CON_RESTART_EN | speed;
>
> /* Try first if we can configure the device from ACPI */
> r = dw_i2c_acpi_configure(pdev);
> --
> 1.7.9.5
>
> --
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