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    SubjectRe: [PATCH 1/2] PM / Runtime: Add sysfs switch for disabling device run-time PM (rev. 2)
    Date
    On Thursday 04 February 2010, Pavel Machek wrote:
    > Hi!
    >
    > > /*
    > > + * control - Report/change current runtime PM setting of the device
    > > + *
    > > + * Runtime power management of a device can be blocked with the help of
    > > + * this attribute. All devices have one of the following two values for
    > > + * the power/control file:
    > > + *
    > > + * + "auto\n" to allow the device to be power managed at run time;
    > > + * + "on\n" to prevent the device from being power managed at run time;
    >
    > I find interface with mandatory \n quite 'interesting'.

    This simply follows the other descriptions in this file.

    > Plus english is strange here. All devices have ... "auto" to allow...?
    > Strange formulation. List the values first, then add "write ... to allow"?

    Ditto.

    > > + * The default for all devices is "auto", which means that devices may be
    > > + * subject to automatic power management, depending on their drivers.
    >
    > Is it wise to specify 'auto' default value for devices without runtime
    > pm?

    Yes, it is. It means the user space doesn't care whether or not the device is
    power managed at run-time.

    > > +static ssize_t control_store(struct device * dev, struct device_attribute *attr,
    > > + const char * buf, size_t n)
    > > +{
    > > + char *cp;
    > > + int len = n;
    > > +
    > > + cp = memchr(buf, '\n', n);
    > > + if (cp)
    > > + len = cp - buf;
    > > + if (len == sizeof ctrl_auto - 1 && strncmp(buf, ctrl_auto, len) == 0)
    > > + pm_runtime_allow(dev);
    >
    > parenthesis after sizeof?

    This notation is used throughout this file too.

    > Do I read it correctly that all of
    >
    > "auto"
    > "auto\n"
    > "auto\non\nIm confused"
    >
    > will switch to auto?

    Perhaps it would, but what exactly is the problem with that?

    Rafael


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