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Date: Wed, 26 Sep 2012 13:39:10 +0200
Message-ID: <CACRpkdbQ4PMVbLuKT-i1dt2oYUYadJ6iw7X-xvAiXjveHAn-Hw@mail.gmail.com>
Subject: Re: [RFC PATCH 2/17] input: RMI4 core bus and sensor drivers.
From: Linus Walleij <linus.walleij@linaro.org>
To: Christopher Heiny <cheiny@synaptics.com>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        Jean Delvare <khali@linux-fr.org>,
        Linux Kernel <linux-kernel@vger.kernel.org>,
        Linux Input <linux-input@vger.kernel.org>,
        Allie Xiong <axiong@synaptics.com>,
        William Manson <wmanson@synaptics.com>,
        Peichen Chang <peichen.chang@synaptics.com>,
        Joerie de Gram <j.de.gram@gmail.com>,
        Wolfram Sang <w.sang@pengutronix.de>,
        Mathieu Poirier <mathieu.poirier@linaro.org>,
        Linus Walleij <linus.walleij@stericsson.com>,
        Naveen Kumar Gaddipati <naveen.gaddipati@stericsson.com>,
        Greg KH <gregkh@linuxfoundation.org>,
        "Rafael J. Wysocki" <rjw@sisk.pl>, Magnus Damm <magnus.damm@gmail.com>
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On Wed, Sep 26, 2012 at 1:53 AM, Christopher Heiny <cheiny@synaptics.com> wrote:

>>> >+/* Remove access to raw format string versions */
>>> >+/*#undef simple_show_union_struct
>>> >+#undef show_union_struct_unsigned
>>> >+#undef show_store_union_struct
>>> >+#undef show_repeated_union_struct
>>> >+#undef show_store_repeated_union_struct*/
>>
>> This looks like trying to reimplement ioctl() in sysfs.
>>
>> If what you want is to send big structs in/out of the kernel,
>> use either ioctl() on device nodes (should be trivial since input
>> is using real device nodes) or use configfs.
>
> I'm a little confused.  There's repeated emphasis in the kernel doc that you
> shouldn't use ioctl() anymore - use sysfs instead.  So we've been using
> sysfs, though it seems somewhat klutzy.  If it's actually OK to use ioctl(),
> that could simplify things.  On the other hand, using configfs might be more
> appropriate.

OK yes configfs is said to be ideal for large configuration chunks,
I haven't really used it.

sysfs has this concept of one value per file, and that turns into the
above serialization/marshalling code if followed, so it doesn't look
good. Maybe configfs is the silver bullet.

Yours,
Linus Walleij