linux-kernel - Re: [PATCH v3] PM / core: conditionally skip system pm in device/driver model

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Message-ID: <Zdi3UWWRfKw1N_Jn@smile.fi.intel.com>
Date: Fri, 23 Feb 2024 17:18:41 +0200
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Guan-Yu Lin <guanyulin@...gle.com>
Cc: rafael@...nel.org, pavel@....cz, len.brown@...el.com,
	gregkh@...uxfoundation.org, petr.tesarik.ext@...wei.com,
	rdunlap@...radead.org, james@...iv.tech, broonie@...nel.org,
	james.clark@....com, masahiroy@...nel.org,
	linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org
Subject: Re: [PATCH v3] PM / core: conditionally skip system pm in
 device/driver model

On Fri, Feb 23, 2024 at 02:38:29PM +0000, Guan-Yu Lin wrote:
> In systems with a main processor and a co-processor, asynchronous
> controller management can lead to conflicts.  One example is the main
> processor attempting to suspend a device while the co-processor is
> actively using it. To address this, we introduce a new sysfs entry
> called "conditional_skip". This entry allows the system to selectively
> skip certain device power management state transitions. To use this
> feature, set the value in "conditional_skip" to indicate the type of
> state transition you want to avoid.  Please review /Documentation/ABI/
> testing/sysfs-devices-power for more detailed information.

..

> +static ssize_t conditional_skip_store(struct device *dev,
> +				      struct device_attribute *attr,
> +				      const char *buf, size_t n)
> +{

> +	int ret;

> +	if (kstrtoint(buf, 0, &ret))

Why is it int? It seems like flags, should not be unsigned as u32 or so?

> +		return -EINVAL;

Do not shadow the real error code without justification.

> +	ret &= (PM_EVENT_FREEZE|PM_EVENT_SUSPEND|PM_EVENT_HIBERNATE);
> +
> +	dev->power.conditional_skip_pm = ret;
> +
> +	return n;
> +}

> +

Redundant blank line.

> +static DEVICE_ATTR_RW(conditional_skip);

-- 
With Best Regards,
Andy Shevchenko