linux-kernel - Re: [PATCH 1/2] i2c: imx: I2C Driver doesn't consider I2C_IPGCLK

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Date:   Tue, 30 Apr 2019 14:50:43 +0200
From:   Sascha Hauer <s.hauer@...gutronix.de>
To:     Chuanhua Han <chuanhua.han@....com>
Cc:     shawnguo@...nel.org, leoyang.li@....com, robh+dt@...nel.org,
        mark.rutland@....com, linux-kernel@...r.kernel.org,
        linux-i2c@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        devicetree@...r.kernel.org, festevam@...il.com, linux-imx@....com,
        wsa+renesas@...g-engineering.com, u.kleine-koenig@...gutronix.de,
        eha@...f.com, linux@...pel-privat.de, l.stach@...gutronix.de,
        peda@...ntia.se, sumit.batra@....com
Subject: Re: [PATCH 1/2] i2c: imx: I2C Driver doesn't consider I2C_IPGCLK_SEL
 RCW bit when using ls1046a SoC

On Tue, Apr 30, 2019 at 12:47:18PM +0800, Chuanhua Han wrote:
> The current kernel driver does not consider I2C_IPGCLK_SEL (424 bit
> of RCW) in deciding  i2c_clk_rate in function i2c_imx_set_clk()
> { 0 Platform clock/4, 1 Platform clock/2}.
> 
> When using ls1046a SoC, this populates incorrect value in IBFD register
> if I2C_IPGCLK_SEL = 0, which generates half of the desired Clock.
> 
> Therefore, if ls1046a SoC is used, we need to set the i2c clock
> according to the corresponding RCW.

So the clock driver reports the wrong clock. Please fix the clock driver
then.

Sascha

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