Re: [PATCH 2/5] i2c: designware: allow IP specific sda_hold_time

From: Andy Shevchenko
Date: Tue Jul 17 2018 - 10:33:44 EST


On Tue, 2018-07-17 at 13:48 +0200, Alexandre Belloni wrote:
> Because some old designware IPs were not supporting setting an SDA
> hold
> time, vendors developed their own solution. Add a way for the final
> driver
> to provide its own SDA hold time handling.
>

Thanks for information you provided. See my comment below.
After addressing it,

Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>

> Signed-off-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxx>
> ---
> drivers/i2c/busses/i2c-designware-common.c | 6 ++++++
> drivers/i2c/busses/i2c-designware-core.h | 1 +
> 2 files changed, 7 insertions(+)
>
> diff --git a/drivers/i2c/busses/i2c-designware-common.c
> b/drivers/i2c/busses/i2c-designware-common.c
> index 9afc3e075b33..545b69d6be3c 100644
> --- a/drivers/i2c/busses/i2c-designware-common.c
> +++ b/drivers/i2c/busses/i2c-designware-common.c
> @@ -297,6 +297,12 @@ void i2c_dw_set_sda_hold_time(struct dw_i2c_dev
> *dev)
> {
> u32 reg;
>

>
> + if (dev->set_sda_hold_time) {
> + dev->set_sda_hold_time(dev);
> +
> + return;
> + }

I would rather inject this, for now (*), into if-else-if ladder, i.e.

if (reg >= DW_IC_SDA_HOLD_MIN_VERS) {
...
} else if (dev->set_sda_hold_time) { // <<<
...
} else if (dev->sda_hold_time) {
...

(*) Since your IP is of v1.10a I don't believe any new version of IP
would shadow existing DW IP registers, thus version check is okay to
have first in my opinion.

> +
> /* Configure SDA Hold Time if required. */
> reg = dw_readl(dev, DW_IC_COMP_VERSION);
> if (reg >= DW_IC_SDA_HOLD_MIN_VERS) {
> diff --git a/drivers/i2c/busses/i2c-designware-core.h
> b/drivers/i2c/busses/i2c-designware-core.h
> index bc43fb9ac1cf..b2778b6d8aca 100644
> --- a/drivers/i2c/busses/i2c-designware-core.h
> +++ b/drivers/i2c/busses/i2c-designware-core.h
> @@ -283,6 +283,7 @@ struct dw_i2c_dev {
> void (*disable)(struct dw_i2c_dev
> *dev);
> void (*disable_int)(struct dw_i2c_dev
> *dev);
> int (*init)(struct dw_i2c_dev *dev);
> + int (*set_sda_hold_time)(struct
> dw_i2c_dev *dev);
> int mode;
> struct i2c_bus_recovery_info rinfo;
> };

--
Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Intel Finland Oy