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

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Message-ID: <dc2cf86a-abf2-b372-29f9-3bfedeb24a97@collabora.com>
Date:   Thu, 14 Sep 2023 11:37:49 +0200
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     Daniel Golle <daniel@...rotopia.org>
Cc:     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,
        郭小桥 <joe@...nstrong.cn>
Subject: Re: [PATCH] i2c: mt65xx: allow optional pmic clock

Il 14/09/23 11:07, Daniel Golle ha scritto:
> On Wed, Sep 13, 2023 at 04:00:53PM +0200, AngeloGioacchino Del Regno wrote:
>> 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?
> 
> No, if I wanted that I could have used the existing 'mediatek,have-pmic'
> property -- however, all needed e.g. on MT7981 is to make sure the
> clock is enabled, but still use I2C_MT65XX_CLK_MAIN as speed_clk.
> 

Sorry, I've misunderstood the intention and yes, I understand now.

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>