linux-kernel - Re: [PATCH] i2c: exynos5: Calculate t_scl_l, t_scl

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Message-ID: <ZTaNaH8qo3Ho+yvL@ninjato>
Date:   Mon, 23 Oct 2023 17:12:40 +0200
From:   Wolfram Sang <wsa@...nel.org>
To:     Camel Guo <camel.guo@...s.com>
Cc:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Alim Akhtar <alim.akhtar@...sung.com>,
        linux-i2c@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel@...s.com
Subject: Re: [PATCH] i2c: exynos5: Calculate t_scl_l, t_scl_h according to
 i2c spec

On Mon, Sep 12, 2022 at 10:59:43AM +0200, Camel Guo wrote:
> Previously the duty cycle was divided equally into h_scl_l, t_scl_h.
> This makes the low period of the SCL clock in Fast Mode is only 1.25us
> which is way lower than the minimal value (1.3) specified in i2c
> specification. In order to make sure t_scl_l, t_scl_h always fullfill
> i2c specification, this commit calculates t_scl_l using this formula:
> 
> t_scl_l = clk_cycle *
>     ((t_low_min + (scl_clock - t_low_min - t_high_min) / 2) / scl_clock)
> 
> where:
> t_low_min is the minimal value of low period of the SCL clock in us;
> t_high_min is the minimal value of high period of the SCL clock in us;
> scl_clock is converted from SCL clock frequency into us.
> 
> Signed-off-by: Camel Guo <camel.guo@...s.com>

Applied to for-next, thanks!


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