Re: [PATCH 2/3] input: evdev: add new ioctl EVIOCSIFTYPE / EVIOCGIFTYPE

From: Arnd Bergmann <arnd@arndb.de>
To: WEN Pingbo <pingbo.wen@linaro.org>
Cc: y2038@lists.linaro.org, linux-api@vger.kernel.org,
	dmitry.torokhov@gmail.com, linux-kernel@vger.kernel.org,
	aksgarg1989@gmail.com, linux-input@vger.kernel.org
Subject: Re: [PATCH 2/3] input: evdev: add new ioctl EVIOCSIFTYPE / EVIOCGIFTYPE
Date: Fri, 27 Nov 2015 17:59:04 +0100	[thread overview]
Message-ID: <2705528.qSj27KAuDS@wuerfel> (raw)
In-Reply-To: <1448618432-32357-3-git-send-email-pingbo.wen@linaro.org>

On Friday 27 November 2015 18:00:31 WEN Pingbo wrote:
> This patch depends on 'introduce new evdev interface'.
> 
> Userspace cat set / get evdev interface type via the two ioctl
> commands. And default interface type is EV_IF_LEGACY, so the old binary
> will work normal with new kernel. Maybe we should change this default
> option to encourage people to move to new interface.
> 
> And since all events are stored as input_value in evdev, there are no
> need to flush evdev_client's buffer if we change clk_type and if_type.

I would split out the change to evdev_set_clk_type into a separate patch.

> +	case EVIOCSIFTYPE:
> +		if (get_user(if_type, ip))
> +			return -EFAULT;
> +
> +		return evdev_set_if_type(client, if_type);
> +	case EVIOCGIFTYPE:
> +		return put_user(client->if_type, ip);
>  	}

This look asymmetric: EVIOCSIFTYPE uses a EVDEV_* constant, while
EVIOCGIFTYPE returns a EV_IF_* constant. Should those just
be the same constants anyway?

	Arnd
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