From mboxrd@z Thu Jan  1 00:00:00 1970
From: Greg KH <greg@kroah.com>
Subject: Re: [RFC][PATCH] input: Introduce device information ioctl
Date: Tue, 7 Dec 2010 08:22:22 -0800
Message-ID: <20101207162222.GA32237@kroah.com>
References: <1291706726-8835-1-git-send-email-rydberg@euromail.se>
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To: Henrik Rydberg <rydberg@euromail.se>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>, Jiri Kosina <jkosina@suse.cz>, linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, Ping Cheng <pingc@wacom.com>, Chris Bagwell <chris@cnpbagwell.com>

On Tue, Dec 07, 2010 at 08:25:26AM +0100, Henrik Rydberg wrote:
>  /**
> + * struct input_devinfo - device information via EVIOCGDEVINFO ioctl
> + * @types: bitmask of types (DEVTYPE_*) matching this device
> + * @capabilities: bitmask of capabilities (DEVCAPS_*) of this device
> + *
> + * This struct provides information about the device needed for
> + * automatic setup in userspace, such as if the device is direct
> + * (touchscreen) or indirect (touchpad), and if there are other
> + * special considerations, such as the touchpad also being a button.
> + */
> +struct input_devinfo {
> +	__u32 types;
> +	__u32 capabilities;
> +};

Why use an ioctl for this at all?  It's just 2 simple values that don't
need to be atomically read at the same time.  What's wrong with 2 more
sysfs files?

thanks,

greg k-h