linux-kernel - Re: [PATCH] i2c: mt65xx: allow optional pmic clock

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Date:   Wed, 13 Sep 2023 16:00:53 +0200
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     Daniel Golle <daniel@...rotopia.org>,
        Qii Wang <qii.wang@...iatek.com>,
        Andi Shyti <andi.shyti@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org
Cc:     郭小桥 <joe@...nstrong.cn>
Subject: Re: [PATCH] i2c: mt65xx: allow optional pmic clock

Il 27/08/23 04:13, Daniel Golle ha scritto:
> Using the I2C host controller on the MT7981 SoC requires 4 clocks to
> be enabled. One of them, the pmic clk, is only enabled in case
> 'mediatek,have-pmic' is also set which has other consequences which
> are not desired in this case.
> 
> Allow defining a pmic clk even in case the 'mediatek,have-pmic' propterty
> is not present and the bus is not used to connect to a pmic, but may
> still require to enable the pmic clock.
> 
> Signed-off-by: Daniel Golle <daniel@...rotopia.org>
> ---
>   drivers/i2c/busses/i2c-mt65xx.c | 12 ++++++++----
>   1 file changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-mt65xx.c b/drivers/i2c/busses/i2c-mt65xx.c
> index 1a9b5a068ef1b..a8b5719c33729 100644
> --- a/drivers/i2c/busses/i2c-mt65xx.c
> +++ b/drivers/i2c/busses/i2c-mt65xx.c
> @@ -1442,15 +1442,19 @@ static int mtk_i2c_probe(struct platform_device *pdev)
>   	if (IS_ERR(i2c->clocks[I2C_MT65XX_CLK_ARB].clk))
>   		return PTR_ERR(i2c->clocks[I2C_MT65XX_CLK_ARB].clk);
>   
> +	i2c->clocks[I2C_MT65XX_CLK_PMIC].clk = devm_clk_get_optional(&pdev->dev, "pmic");
> +	if (IS_ERR(i2c->clocks[I2C_MT65XX_CLK_PMIC].clk)) {
> +		dev_err(&pdev->dev, "cannot get pmic clock\n");
> +		return PTR_ERR(i2c->clocks[I2C_MT65XX_CLK_PMIC].clk);
> +	}
> +
>   	if (i2c->have_pmic) {

...but you're not changing speed_clk if !i2c->have_pmic, I'm not sure that
this will work correctly. Perhaps you wanted to also set speed_clk if the
clock is present?

if (IS_ERR...) {
	error handling
} else if (clk is present)
	speed_clk = I2C_MT65XX_CLK_PMIC;

if (have_pmic && !clk_is_present)
	error

Regards,
Angelo

> -		i2c->clocks[I2C_MT65XX_CLK_PMIC].clk = devm_clk_get(&pdev->dev, "pmic");
> -		if (IS_ERR(i2c->clocks[I2C_MT65XX_CLK_PMIC].clk)) {
> +		if (!i2c->clocks[I2C_MT65XX_CLK_PMIC].clk) {
>   			dev_err(&pdev->dev, "cannot get pmic clock\n");
> -			return PTR_ERR(i2c->clocks[I2C_MT65XX_CLK_PMIC].clk);
> +			return -ENODEV;
>   		}
>   		speed_clk = I2C_MT65XX_CLK_PMIC;
>   	} else {
> -		i2c->clocks[I2C_MT65XX_CLK_PMIC].clk = NULL;
>   		speed_clk = I2C_MT65XX_CLK_MAIN;
>   	}
>