On Fri, Aug 31, 2012 at 08:37:26PM -0400, Forest Bond wrote:
> From: Forest Bond <forest.bond@rapidrollout.com>
> 
> Certain eGalax devices expose an interface with class HID and protocol
> None.  Some work with usbhid and some work with usbtouchscreen, but
> there is no easy way to differentiate.  Sending an eGalax diagnostic
> packet seems to kick them all into using the right protocol for
> usbtouchscreen, so we can continue to bind them all there (as opposed to
> handing some off to usbhid).
> 
> This fixes a regression for devices that were claimed by (and worked
> with) usbhid prior to commit 139ebe8dc80dd74cb2ac9f5603d18fbf5cff049f
> ("Input: usbtouchscreen - fix eGalax HID ignoring"), which made
> usbtouchscreen claim them instead.  With this patch they will still be
> claimed by usbtouchscreen, but they will actually report events
> usbtouchscreen can understand.  Note that these devices will be limited
> to the usbtouchscreen feature set so e.g. dual touch features are not
> supported.
> 
> I have the distinct pleasure of needing to support devices of both types
> and have tested accordingly.
> 
> Signed-off-by: Forest Bond <forest.bond@rapidrollout.com>
> ---
>  drivers/input/touchscreen/usbtouchscreen.c |   36 ++++++++++++++++++++++++++++
>  1 files changed, 36 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/input/touchscreen/usbtouchscreen.c b/drivers/input/touchscreen/usbtouchscreen.c
> index e32709e..64b4b17 100644
> --- a/drivers/input/touchscreen/usbtouchscreen.c
> +++ b/drivers/input/touchscreen/usbtouchscreen.c
> @@ -304,6 +304,41 @@ static int e2i_read_data(struct usbtouch_usb *dev, unsigned char *pkt)
>  #define EGALAX_PKT_TYPE_REPT		0x80
>  #define EGALAX_PKT_TYPE_DIAG		0x0A
>  
> +static int egalax_init(struct usbtouch_usb *usbtouch)
> +{
> +	int ret, i;
> +	unsigned char *buf;
> +	struct usb_device *udev = interface_to_usbdev(usbtouch->interface);
> +
> +	/* An eGalax diagnostic packet kicks the device into using the right
> +	 * protocol.  We send a "check active" packet.  The response will be
> +	 * read later and ignored.
> +	 */
> +
> +	buf = kmalloc(3, GFP_KERNEL);

	if (!buf)
		return -ENOMEM;

> +	buf[0] = EGALAX_PKT_TYPE_DIAG;
> +	buf[1] = 1;	/* length */
> +	buf[2] = 'A';	/* command - check active */
> +
> +	for (i = 0; i < 3; i++) {
> +		ret = usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
> +				      0,
> +				      USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
> +				      0, 0, buf, 3,
> +				      USB_CTRL_SET_TIMEOUT);
> +		if (ret >= 0) {
> +			ret = 0;
> +			break;
> +		}
> +		if (ret != -EPIPE)
> +			break;
> +	}
> +
> +	kfree(buf);
> +
> +	return ret;
> +}