linux-kernel - Re: [PATCH v1 3/3] misc: Add meta cld driver

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Message-ID: <Y8Z1JxsLA6UKi805@kroah.com>
Date:   Tue, 17 Jan 2023 11:15:03 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Delphine CC Chiu <Delphine_CC_Chiu@...ynn.com>
Cc:     patrick@...cx.xyz, Derek Kiernan <derek.kiernan@...inx.com>,
        Dragan Cvetic <dragan.cvetic@...inx.com>,
        Arnd Bergmann <arnd@...db.de>, garnermic@...com,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Stanislav Jakubek <stano.jakubek@...il.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Samuel Holland <samuel@...lland.org>,
        linux-i2c@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 3/3] misc: Add meta cld driver

On Tue, Jan 17, 2023 at 05:44:22PM +0800, Delphine CC Chiu wrote:
> Add support for meta control-logic-device driver. The CLD manages the
> server system power squence and other state such as host-power-state,
> uart-selection and presense-slots. The baseboard management controller
> (BMC) can access the CLD through I2C.
> 
> The version 1 of CLD driver is supported. The registers number, name
> and mode of CLD can be defined in dts file for version 1. The driver
> exports the filesystem following the dts setting.
> 
> Signed-off-by: Delphine CC Chiu <Delphine_CC_Chiu@...ynn.com>
> Tested-by: Bonnie Lo <Bonnie_Lo@...ynn.com>
> ---
>  MAINTAINERS                         |   6 +
>  drivers/misc/Kconfig                |   9 +
>  drivers/misc/Makefile               |   1 +
>  drivers/misc/control-logic-device.c | 443 ++++++++++++++++++++++++++++

That is a very generic name for a very specific driver.  Please make it
more hardware-specific.

Also, you add a bunch of undocumented sysfs files here, which require a
Documentation/ABI/ entries so that we can review the code to verify it
does what you all think it does.

And finally, why is this needed to be a kernel driver at all?  Why can't
you control this all through the userspace i2c api?

One review comment:

> +static int cld_remove(struct i2c_client *client)
> +{
> +	struct device *dev = &client->dev;
> +	struct cld_client *cld = dev_get_drvdata(dev);
> +
> +	if (cld->task) {
> +		kthread_stop(cld->task);
> +		cld->task = NULL;
> +	}
> +
> +	devm_kfree(dev, cld);

Whenever you see this line in code, it's almost always a huge red flag
that someone is not using the devm_* api properly.  I think that is most
certainly the case here.

thanks,

greg k-h