linux-kernel - Re: [RFC PATCH 01/06] input/rmi4: Public header and documentation

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Message-ID: <5087204A.3080303@synaptics.com>
Date:	Tue, 23 Oct 2012 15:55:06 -0700
From:	Christopher Heiny <cheiny@...aptics.com>
To:	Dmitry Torokhov <dmitry.torokhov@...il.com>
CC:	Linus Walleij <linus.walleij@...aro.org>,
	Anton Vorontsov <anton.vorontsov@...aro.org>,
	Mark Brown <broonie@...nsource.wolfsonmicro.com>,
	Jean Delvare <khali@...ux-fr.org>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Linux Input <linux-input@...r.kernel.org>,
	Allie Xiong <axiong@...aptics.com>,
	Vivian Ly <vly@...aptics.com>,
	Daniel Rosenberg <daniel.rosenberg@...aptics.com>,
	Joerie de Gram <j.de.gram@...il.com>,
	Wolfram Sang <w.sang@...gutronix.de>,
	Mathieu Poirier <mathieu.poirier@...aro.org>,
	Linus Walleij <linus.walleij@...ricsson.com>,
	Naveen Kumar Gaddipati <naveen.gaddipati@...ricsson.com>,
	Alexandra Chin <alexandra.chin@...synaptics.com>
Subject: Re: [RFC PATCH 01/06] input/rmi4: Public header and documentation

On 10/11/2012 01:24 AM, Dmitry Torokhov wrote:
> On Thu, Oct 11, 2012 at 03:41:41AM +0000, Christopher Heiny wrote:
>> >Linus Walleij wrote:
>>> > >On Sat, Oct 6, 2012 at 6:09 AM, Christopher Heiny<cheiny@...aptics.com>  wrote:
>>> > >
>>>> > > >+#ifdef CONFIG_RMI4_DEBUG
>>>> > > >+/**
>>>> > > >+ * Utility routine to handle writes to read-only attributes.  Hopefully
>>>> > > >+ * this will never happen, but if the user does something stupid, we
>>>> > > >don't
>>>> > > >+ * want to accept it quietly (which is what can happen if you just put
>>>> > > >NULL + * for the attribute's store function).
>>>> > > >+ */
>>>> > > >+static inline ssize_t rmi_store_error(struct device *dev,
>>>> > > >+                       struct device_attribute *attr,
>>>> > > >+                       const char *buf, size_t count)
>>>> > > >+{
>>>> > > >+       dev_warn(dev,
>>>> > > >+                "WARNING: Attempt to write %d characters to read-only
>>>> > > >attribute %s.", +               count, attr->attr.name);
>>>> > > >+       return -EPERM;
>>>> > > >+}
>>> > >
>>> > >Here it looks like you're hiding a lot of stuff that should be dev_warn()?
>>> > >Consider my earlier point about dynamic debug.
>> >
>> >In previous patch submissions, we always used these warning functions.
>> >But in the feedback on those patches, we were asked to just make sysfs
>> >show/store NULL if the attribute is write/read only.  However, during
>> >their development process, our customers want to see the warnings if
>> >the attributes are accessed incorrectly.  So we made these warnings a
>> >debug option.
 >
> I think it is the case when customer is not always right. Given that
> the attributes are created with S_IRUGO mask how will we even get these
> methods to fire?

We were able to get those to fire in earlier kernels under some UIs 
(such as Android).  However, we no longer support those earlier version. 
  I have checked the behavior on up-to-date kernels and UI versions, and 
everyone seems to handle this correctly.  That means we can drop these 
definitions entirely, so we'll do that.
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