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    SubjectRe: [lm-sensors] [PATCH] hwmon class driver registration with a device number
    On Thu, Oct 06, 2011 at 09:43:02AM +0200, Jean Delvare wrote:
    >

    Thanks Jean for summing up the questions :)

    > I again agree. Which means that Himanshu is still 3 steps away from
    > getting his patch accepted:
    > * Explaining why the current sysfs interface is insufficient and can't
    > be fixed.

    AFAIK, the current sysfs interface is to read standard attributes from
    the device. My reasoning is:

    1. This will give hwmon devices to have their "dev" in their sysfs folder
    as like other classes and in turn be visible in /dev by mdev or udev.

    2. Implementing IOCTL if required. I know that kernel hackers believe
    they are "backdoors" and "can't be done right" but sometimes there
    isn't any get away with them. I don't know when their support will
    be completely removed. Rather, I see that instead of deprecation,
    new IOCTL vectors like compat_ioctl have been introduced.

    > * Getting official device node numbers registered for hwmon use.

    Jean, as long as drivers get major device numbers on the fly, I don't
    think this is a requirement. Isn't it?

    > * Defining an API for these device nodes.
    My idea is just this:
    1. Get a major number from kernel on the fly.
    2. During probing, for each device, call "hwmon_device_register_numbered"
    and let mdev create a /dev node for it. I don't say that this interface
    be imposed on drivers. If they want they can still call "hwmon_device_register"
    if they don't want to implement standard ioctl, read, write calls.

    > Before then, there's no point in resending this patch, it will be
    > rejected.
    >

    Thanks for reviewing. These are my thoughts. If you guys think the reasoning
    isn't strong enough to get this in mainline, I am happy to accept that :)
    At least I know what can get rejected for sure and I am happy to build a
    stack of rejected patches for that. :)

    -Himanshu


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