Re: [linux-usb-devel] [PATCH] Add some PID stuff and fix HID debug prettyprinting

[Vojtech P. <vo...@su...>]

On Wed, Jan 16, 2002 at 05:38:56PM +0100, Bj|rn Augustsson wrote:
> Quoting Johann Deneux <jo...@Do...>:
> > [cc to the linuxconsole list]
> > (Bj|rn is currently working on support for force feedback for microsoft
> > joysticks, and sent a patch to the usb-devel ML concerning the debugging
> > system of the hid driver)
> > 
> > On Wed, 16 Jan 2002, Bj|rn Augustsson wrote:
> > 
> > > Nope, 1.8 is what I've got here.
> > > 
> > > I'll certainly look into that. Thanks for the heads up!
> > > 
> > > I have quite a lot more written, but there's still some bugs and stuff
> > > that I haven't implemented yet, so I split this part out.
> > 
> > How far have you got ? Have you managed to make your joystick move yet ?
> > Please also have a look at the input/event API. It would be nice if it was
> > the one used to download effects to the device.
> 
> No, I haven't, but I'm close. (I think!)
> 
> OK, longish status update time:
> 
> I am using the event API. The joystick now reports almost all of it's 
> features to the event stuff, but actually writing stuff to the it 
> doesn't work yet.  I haven't started on uploading effects, but I thought
> I had the "set device gain" thing working last night, but I ran into 
> problems where this happens:
> 
> Jan 16 03:49:06 localhost kernel: Setting device gain to 127, span = 255
> Jan 16 03:49:06 localhost kernel: hid-debug: input PhysicalInterfaceDevice.Device_Gain = 127
> Jan 16 03:49:06 localhost kernel: hid-core.c: ctrl urb status -32 received
> 
> -32 is EPIPE, and I'll have to look into why that happens a bit later today.
> 
> The joystick actually seems to be a proper PID device, so that's what
> I'm aiming for, and trying not to hard-code anything MS-FF2-specific in
> there.
> 
> There's a few policy type things to consider. There's an Usage called
> PhysicalInterfaceDevice.Safety_Switch, which is a switch that notices if
> you hold the joystick or not (and if you let go, it turns the forces
> off). Since the existing HID-input "parser" reports every one-bit input
> usage as a button, this gets reported that way (except it's inverted, if
> you let go of the stick, it goes 0 -> 1). 
> 
> It's not really a button, but it could be useful to a game anyway. You
> could bind pause to it for example, or something. Do I report it to the
> API as a button, or do I add a new bit about this somewhere?

It's already defined: BTN_DEAD (The 'deadman' switch).

> Also, HID devices (can) have physical units bound to them, as in "This
> axis measues rotation, +- 30 degrees, 8bit resolution." There is no way
> for an app to get this information thru the input API, and it should
> probably be added at some point. It's not critical for game controllers,
> but other apps might want that information.

Yes, we may later add some IOCTLs to report and structures to hold that
information.

> (But as I said, I'll have to look at the current hid code, as I've been
> working against what's in 2.4.18pre3. Maybe things have changed.)

There is a lot of differences, namely in the control URB handling.

-- 
Vojtech Pavlik
SuSE Labs