linux-kernel - Re: [PATCH v6 4/5] i2c: aspeed: added driver for Aspeed I2C

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Message-ID: <1490691470.3177.114.camel@kernel.crashing.org>
Date:   Tue, 28 Mar 2017 19:57:50 +1100
From:   Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:     Brendan Higgins <brendanhiggins@...gle.com>, wsa@...-dreams.de,
        robh+dt@...nel.org, mark.rutland@....com, tglx@...utronix.de,
        jason@...edaemon.net, marc.zyngier@....com, joel@....id.au,
        vz@...ia.com, mouse@...c.ru, clg@...d.org
Cc:     linux-i2c@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, openbmc@...ts.ozlabs.org
Subject: Re: [PATCH v6 4/5] i2c: aspeed: added driver for Aspeed I2C

On Mon, 2017-03-27 at 22:12 -0700, Brendan Higgins wrote:
> +/* 0x04 : I2CD Clock and AC Timing Control Register #1 */
> +#define ASPEED_I2CD_TIME_SCL_HIGH_SHIFT                        16
> +#define ASPEED_I2CD_TIME_SCL_HIGH_MASK                 GENMASK(19, 16)
> +#define ASPEED_I2CD_TIME_SCL_LOW_SHIFT                 12
> +#define ASPEED_I2CD_TIME_SCL_LOW_MASK                  GENMASK(15, 12)
> +#define ASPEED_I2CD_TIME_BASE_DIVISOR_MASK             GENMASK(3, 0)
> +#define ASPEED_I2CD_TIME_SCL_REG_MAX                   GENMASK(3, 0)
> +/* 0x08 : I2CD Clock and AC Timing Control Register #2 */
> +#define ASPEED_NO_TIMEOUT_CTRL                         0

Those are slightly different between the 2400 and 2500, allowing
slightly more fine grained settings (faster base clock and thus higher
numbers in high/low counts).

I *think* that using the 2400 values as-is might work ok, at least
it does for 100kHz but I would double check.

I'll review the rest tomorrow.

Cheers,
Ben.