Re: [PATCH] Input: usbtouchscreen - initialize eGalax devices

[Sergei Shtylyov <sshtylyov@mvista.com>]

Hello.

On 08/31/2012 05:56 PM, 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,

   Please also specify that commit's summary ion parens.

> 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 |   25 +++++++++++++++++++++++++
>  1 files changed, 25 insertions(+), 0 deletions(-)

> diff --git a/drivers/input/touchscreen/usbtouchscreen.c b/drivers/input/touchscreen/usbtouchscreen.c
> index e32709e..2ce5308 100644
> --- a/drivers/input/touchscreen/usbtouchscreen.c
> +++ b/drivers/input/touchscreen/usbtouchscreen.c
> @@ -304,6 +304,30 @@ 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;
> +	struct usb_device *udev = interface_to_usbdev(usbtouch->interface);
> +
> +	/* An eGalax diagnostic packet kicks the device into using the right
> +	 * protocol. */

   The preferred multi-line comment style is:

/*
 * bla
 * bla
 */

> +	for (i = 0; i < 3; i++) {
> +		/* Send a "check active" packet. The response will be read
> +		 * later and ignored. */
> +		ret = usb_control_msg(udev, usb_rcvctrlpipe(udev, 0),
> +				      0,
> +				      USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
> +				      0, 0, "\x0A\x01A", 0,

   You probably can't send data from the .const section (as well as off the
stack) -- they can be DMA'ed and there'll be issues with cache consistency on
non-x86 arches. You should allocate the data with kmalloc().
   Although, on the second thought, maybe I'm wrong in this case... not really
sure about sending -- receiving (to the .data section) could certainly be harmful...

WBR, Sergei