Why? I thought this thing is an input device? Why does an
application have to modify a running device? Is this modification local
to the application<->device interface or does it also affect all other
running applications that use this device? If it is a configuration
value to put the device into a different state or similar, then you can
use a sysfs attribute. The user can change this with "echo <value>
>/sys/class/input/inputX/<attribute>"
I'm already with working examples of ATTRIB in my driver project. The
thing is that I have random kernel panics when I try to read from the
attribute. This is my attribute code:
static ssize_t usbtouchscreen_get_state(struct device *dev, struct
device_attribute *attr, char *buf)
{
int count=0;
struct usbtouch_usb *usbtouch = dev_get_drvdata(dev);
struct dpx_priv *priv = usbtouch->priv;
printk(KERN_INFO "state length: %d",sizeof(DPX_DEVICE_STATE)); //
size = 43196 bytes
memcpy(buf,(void*)&priv->context->State,sizeof(DPX_DEVICE_STATE));
return sizeof(DPX_DEVICE_STATE);
}
static DEVICE_ATTR(state, 0777, usbtouchscreen_get_state, NULL);
Should I make anykind of protection while doing this operation? I have
read in some answer from you guys, that I should create an attribute for
every field of the structure I want to bring to userspace, but that will
make me have tenths of attributes. The problem for me are not the number
of attributes, but the changes I will need to have in my control panel
to support that architecture. One attribute with the content of State
variable would be perfect.
Any ideas?
Thanks,
Nuno
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