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SubjectRe: [PATCH 1/2] i2c designware make SCL and SDA falling time configurable
On Tue, Oct 08, 2013 at 05:00:54PM +0200, Romain Baeriswyl wrote:
> static void __i2c_dw_enable(struct dw_i2c_dev *dev, bool enable)
> @@ -286,6 +287,7 @@ int i2c_dw_init(struct dw_i2c_dev *dev)
> u32 input_clock_khz;
> u32 hcnt, lcnt;
> u32 reg;
> + u32 sda_falling_time, scl_falling_time;
>
> input_clock_khz = dev->get_clk_rate_khz(dev);
>
> @@ -307,15 +309,25 @@ int i2c_dw_init(struct dw_i2c_dev *dev)
>
> /* set standard and fast speed deviders for high/low periods */
>
> + if (dev->sda_falling_time)
> + sda_falling_time = dev->sda_falling_time;
> + else
> + sda_falling_time = 300; /* ns */

I think this looks better:

sda_falling_time = dev->sda_falling_time ? dev->sda_falling_time : 300;

> +
> + if (dev->scl_falling_time)
> + scl_falling_time = dev->scl_falling_time;
> + else
> + scl_falling_time = 300; /* ns */

Ditto.

> +
> /* Standard-mode */
> hcnt = i2c_dw_scl_hcnt(input_clock_khz,
> - 40, /* tHD;STA = tHIGH = 4.0 us */
> - 3, /* tf = 0.3 us */
> + 4000, /* tHD;STA = tHIGH = 4.0 us */
> + sda_falling_time,
> 0, /* 0: DW default, 1: Ideal */
> 0); /* No offset */
> lcnt = i2c_dw_scl_lcnt(input_clock_khz,
> - 47, /* tLOW = 4.7 us */
> - 3, /* tf = 0.3 us */
> + 4700, /* tLOW = 4.7 us */
> + scl_falling_time,
> 0); /* No offset */
>
> /* Allow platforms to specify the ideal HCNT and LCNT values */


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