On Tue, Nov 9, 2010 at 8:28 AM, Chris Bagwell <chris@xxxxxxxxxxxxxx> wrote: > On Tue, Nov 9, 2010 at 12:59 AM, Dmitry Torokhov > <dmitry.torokhov@xxxxxxxxx> wrote: >> On Tue, Nov 09, 2010 at 01:31:49PM +1000, Peter Hutterer wrote: >>> >>> That said, it also goes counter the whole multi-touch approach - allowing >>> more than one device on a single physical device. >>> >> >> So maybe we should teach wacom to handle all devices as a single input device even >> in cases when they use several USB interfaces? We should be able to >> detect related interfaces by examining intf->intf_assoc (I hope) and >> using usb_driver_claim_interface() to claim them. > > Thanks for tips. I may try it just to prove its possible. > > Here is extra info on resolution/dimension issue to also solve when > combining. Taken from current logic on touch input of Wacom Bamboo: > > input_mt_create_slots(input_dev, 2); > input_set_abs_params(input_dev, ABS_MT_POSITION_X, 0, features->x_max, > features->x_fuzz, 0); > > Combining 2 inputs means MT slots increases from 2 to 3 (2 touches and > 1 stylus). > > Today, Pen has x_max=17420, x_fuzz=4 and resolution of 2540. Also > today, Touch has x_max=15360, x_fuzz=128 and resolution=dunno (we are > scaling up touch x_max in driver and I haven't calculated its affects > on resolution). > > I believe that a normalized value of x_max would show that there is a > greater area of tablet can be used for touch then pen. Normalization can be a way to address this issue. But, I am not sure if we want normalization in the kernel. You are onto the right point though. How are we going to pass the different resolution and x/y_max with the same SLOT array? This is an issue we can not avoid for serial MT devices since all data are from the same interface (your case #1). The USB case (your case #2) can work around it since pen and touch are on different logical port. But, I think we want to have an unified approach for both serial and USB to avoid userland inconsistency. What I did in the current code is to report touch x/y_max through ABS_RX/Y so we don't step on ABS_X/Y for serial devices. I know there are people don't like this idea either. So, any more suggestions? Specifying individual resolution and x/y_max for each MT slot is another way to address this issue. But that requires MT implementation and (maybe) spec change. Thank you for thinking out loud. I am sure you understood why I haven't picked up that Bamboo for so long ;). Ping > To handle this difference, we can scale reported values in driver such > that x_max=x_max for all slots. I'm not clear on fuzz logic so don't > know what 4 vs 128 does. > > Or we can maybe update MT interface so you can have per slot values > for clients to query (or MT logic automatically scales for driver as > another option). Then slots 0-1 are reserved for touch and slot 3 is > reserved for pen. > > Chris > -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
