On 07/23/2014 05:42 PM, Benjamin Tissoires wrote:
On Wed, Jul 23, 2014 at 8:42 AM, Nikolai Kondrashov <spbnick@xxxxxxxxx> wrote:
Switch to generating tablet pen report descriptor from a template and
parameters retrieved from string descriptor 0x64.
Signed-off-by: Nikolai Kondrashov <spbnick@xxxxxxxxx>
---
This is a nice solution.
Thanks, Benjamin :)
- rc = usb_string(hid_to_usb_dev(hdev), 0x64, buf, sizeof(buf));
- if (rc < 0)
- return rc;
+ /*
+ * Read string descriptor containing tablet parameters. The specific
+ * string descriptor and data were discovered by sniffing the Windows
+ * driver traffic.
+ * NOTE: This enables fully-functional tablet mode.
+ */
+ rc = usb_control_msg(usb_dev, usb_rcvctrlpipe(usb_dev, 0),
+ USB_REQ_GET_DESCRIPTOR, USB_DIR_IN,
+ (USB_DT_STRING << 8) + 0x64,
+ 0x0409, buf, sizeof(buf),
+ USB_CTRL_GET_TIMEOUT);
Just out of curiosity, you are replacing usb_string() by
usb_control_msg(). They both seem to do the same, so why bother
changing the call?
Well, actually they don't seem to do the same and the main difference is that
usb_string attempts to convert the data from UTF-16LE to UTF-8, which would be
undesirable for the binary contents we expect there.
+ resolution = le16_to_cpu(buf[5]);
+ if (resolution == 0) {
+ params[HUION_PH_ID_X_PM] = 0;
+ params[HUION_PH_ID_Y_PM] = 0;
This is not good (not your code I mean). I know OEMs tend to not care
about resolution, but Wayland will for the tablet protocol. The idea
will be to report the coordinate in mm so that we can have a constant
reporting across vendors/products.
Did you ever fall in this case? and if so, isn't there any way of
retrieving the actual resolution or an approximation?
Thankfully not. This is merely a protection against division-by-zero
exception in case they start doing that.
BTW, it's nice that Wayland tries to actually use the resolution.
The rest looks fair enough, so even with my questions:
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx>
Thanks for the review, Benjamin!
Will send a new version soon.
Sincerely,
Nick
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