From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Torokhov Subject: Re: Interacting with a input kernel driver from user space Date: Mon, 14 Nov 2011 10:57:41 -0800 Message-ID: <201111141057.42310.dmitry.torokhov@gmail.com> References: <4EC10878.20109@edigma.com> <4EC15CD1.2010409@edigma.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: Received: from mail-gy0-f174.google.com ([209.85.160.174]:57794 "EHLO mail-gy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751817Ab1KNS5t (ORCPT ); Mon, 14 Nov 2011 13:57:49 -0500 Received: by gyc15 with SMTP id 15so5201378gyc.19 for ; Mon, 14 Nov 2011 10:57:49 -0800 (PST) In-Reply-To: <4EC15CD1.2010409@edigma.com> Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: Nuno Santos Cc: linux-input@vger.kernel.org On Monday, November 14, 2011 10:24:17 AM Nuno Santos wrote: > Hi, > > I have defined my first attribute in the following way: > > static ssize_t usbtouchscreen_update_sensibility(struct device *dev, > struct device_attribute *attr, > const char *buf, size_t count) > { > > printk(KERN_INFO "update sensibility called"); > Updating sensibility is always a good thing but I gather you mean sensitivity here... BTW this should probably be a per-user setting and belong to the X driver, not kernel driver. I.e. kernel streams all data and userspace (X) decides what data do discard according to current user preferences. > return 0; > } > > static DEVICE_ATTR(sensibility, 0664, NULL, > usbtouchscreen_update_sensibility); > > static struct attribute *usbtouchscreen_attrs[] = { > &dev_attr_sensibility.attr, > NULL > }; > > static const struct attribute_group usbtouchscreen_attr_group = { > .attrs = usbtouchscreen_attrs, > }; > > In the probe function I have added: > > if (sysfs_create_group(&intf->dev.kobj, &usbtouchscreen_attr_group)) > goto out_unregister_input; > > > Then I tried to write on the attribute in the following way: > > nsantos@NS-PC:~/workspaces/linux-kernel-driver$ echo 45 > > /sys/class/input/input7/sensibility > bash: /sys/class/input/input7/sensibility: No such file or directory > > After digging a bit under /sys/class/input/input7 i found that the sub > directory device add sensibilty listed so I tried the following: > > nsantos@NS-PC:~/workspaces/workspace-mtt/linux-kernel-driver$ sudo echo > 45 > /sys/class/input/input7/device/sensibility > bash: /sys/class/input/input7/device/sensibility: Permission denied > > With no success again... > > Am I doing something terribly wrong? You aren't doing this as root and don't have permission to access the attribute. -- Dmitry