linux-kernel - Re: [PATCH v2] i2c: designware: add support for pinctrl for recovery

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Message-ID: <685b10d2-7627-eea8-69e4-454af039fa5d@sionneau.net>
Date:   Thu, 17 Aug 2023 16:27:26 +0200
From:   Yann Sionneau <yann@...nneau.net>
To:     Jarkko Nikula <jarkko.nikula@...ux.intel.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Jan Dabros <jsd@...ihalf.com>,
        Andi Shyti <andi.shyti@...nel.org>
Cc:     linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org,
        Yann Sionneau <ysionneau@...ray.eu>
Subject: Re: [PATCH v2] i2c: designware: add support for pinctrl for recovery

Hi

Le 17/08/2023 à 10:07, Jarkko Nikula a écrit :
> Hi
>
> On 8/16/23 12:50, Yann Sionneau wrote:
>> From: Yann Sionneau <ysionneau@...ray.eu>
>>
>> Currently if the SoC needs pinctrl to switch the SCL and SDA
>> from the I2C function to GPIO function, the recovery won't work.
>>
>> scl-gpio = <>;
>> sda-gpio = <>;
>>
>> Are not enough for some SoCs to have a working recovery.
>> Some need:
>>
>> scl-gpio = <>;
>> sda-gpio = <>;
>> pinctrl-names = "default", "recovery";
>> pinctrl-0 = <&i2c_pins_hw>;
>> pinctrl-1 = <&i2c_pins_gpio>;
>>
>> The driver was not filling rinfo->pinctrl with the device node
>> pinctrl data which is needed by generic recovery code.
>>
>> Tested-by: Yann Sionneau <ysionneau@...ray.eu>
>> Signed-off-by: Yann Sionneau <ysionneau@...ray.eu>
>
> Tested-by from author is needless. Expectation is that author has 
> tested the patch while not always true :-)
Ok, I just wanted to emphasize the fact that I have the device and I 
tested the change with the device. Ack!
>
>> @@ -905,6 +906,15 @@ static int i2c_dw_init_recovery_info(struct 
>> dw_i2c_dev *dev)
>>           return PTR_ERR(gpio);
>>       rinfo->sda_gpiod = gpio;
>>   +    rinfo->pinctrl = devm_pinctrl_get(dev->dev);
>> +    if (IS_ERR(rinfo->pinctrl)) {
>> +        if (PTR_ERR(rinfo->pinctrl) == -EPROBE_DEFER)
>> +            return PTR_ERR(rinfo->pinctrl);
>> +
>> +        rinfo->pinctrl = NULL;
>> +        dev_info(dev->dev, "can't get pinctrl, bus recovery might 
>> not work\n");
>
> I think dev_dbg() suits better here or is it needed at all? End user 
> may not be able to do anything when sees this in dmesg. I.e. more like 
> development time dev_dbg() information.
I agree dev_dbg() is a better idea.
>
> Does i2c-core-base.c: i2c_gpio_init_pinctrl_recovery() already do 
> dev_info() print when pinctrl & GPIO are set properly making above 
> also kind of needless?

Thanks for the review. In fact I had to use gdb to understand why the 
recovery was not working. Because as you said, it only prints something 
to say "everything looks ok!".

I kind of prefer when it prints when something goes wrong.

But I let you decide what you think is the best.

-- 

Yann