linux-kernel - Re: [PATCH] i2c: meson: Fix wrong speed use from probe

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Date:   Mon, 7 Mar 2022 09:46:48 +0100
From:   Neil Armstrong <narmstrong@...libre.com>
To:     Lucas Tanure <tanure@...ux.com>,
        Kevin Hilman <khilman@...libre.com>,
        Jerome Brunet <jbrunet@...libre.com>,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>
Cc:     linux-i2c@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-amlogic@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] i2c: meson: Fix wrong speed use from probe

On 01/03/2022 08:26, Lucas Tanure wrote:
> Having meson_i2c_set_clk_div after i2c_add_adapter
> causes issues for client drivers that try to use
> the bus before the requested speed is applied.
> 
> The bus can be used just after i2c_add_adapter, so
> move i2c_add_adapter to the final step as
> meson_i2c_set_clk_div needs to be called before
> the bus is used.
> 
> Signed-off-by: Lucas Tanure <tanure@...ux.com>
> ---
>   drivers/i2c/busses/i2c-meson.c | 12 ++++++------
>   1 file changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-meson.c b/drivers/i2c/busses/i2c-meson.c
> index ef73a42577cc..07eb819072c4 100644
> --- a/drivers/i2c/busses/i2c-meson.c
> +++ b/drivers/i2c/busses/i2c-meson.c
> @@ -465,18 +465,18 @@ static int meson_i2c_probe(struct platform_device *pdev)
>   	 */
>   	meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_START, 0);
>   
> -	ret = i2c_add_adapter(&i2c->adap);
> -	if (ret < 0) {
> -		clk_disable_unprepare(i2c->clk);
> -		return ret;
> -	}
> -
>   	/* Disable filtering */
>   	meson_i2c_set_mask(i2c, REG_SLAVE_ADDR,
>   			   REG_SLV_SDA_FILTER | REG_SLV_SCL_FILTER, 0);
>   
>   	meson_i2c_set_clk_div(i2c, timings.bus_freq_hz);
>   
> +	ret = i2c_add_adapter(&i2c->adap);
> +	if (ret < 0) {
> +		clk_disable_unprepare(i2c->clk);
> +		return ret;
> +	}
> +
>   	return 0;
>   }
>   

Reviewed-by: Neil Armstrong <narmstrong@...libre.com>