Hello everybody!
I'm working on force feedback support for Saitek gamepad devices. I
base my work on Jérôme Poisson (goffi@xxxxxxxxx) Saitek P2500 driver,
which was written pretty dirty and should be loaded before usbhid to
work.
Logitech/Thrustmaster/ZeroPlus/etc force feedback drivers are
informative enough to build my own driver, but there are still 2
things that I need to clear up:
1. there is always some init code in _probe() function, e.g. for hid-zpff:
> zpff->report = report;
> zpff->report->field[0]->value[0] = 0x00;
> zpff->report->field[1]->value[0] = 0x02;
> zpff->report->field[2]->value[0] = 0x00;
> zpff->report->field[3]->value[0] = 0x00;
> usbhid_submit_report(hid, zpff->report, USB_DIR_OUT);
Jérôme used this code in open() function (input_dev::open field):
> struct usb_device *udev;
> char buf[2];
>
> ...
>
> buf[0]=0x15;
> buf[1]=0x01;
> usb_control_msg(udev, usb_sndctrlpipe(udev, 0), 0x09, 0x21, 0x315, 0, &buf, 2, 50);
May this be replaced by usbhid_submit_report() call and how report
should look like then?
2. in kernell FF drivers all interaction with the device made using
usbhid_submit_report() call, but Jérôme used usb_submit_urb():
> static int SP2500_playback(struct input_dev *dev, int code, int value)
> {
> struct usb_SP2500* sp2500 = (struct usb_SP2500*)(dev->private);
> struct urb *urb = NULL;
> char *buf = NULL;
> int count=4;
> int retval;
>
> urb = usb_alloc_urb(0, GFP_KERNEL);
> if (!urb) {
> retval = -ENOMEM;
> goto error;
> }
>
> buf = usb_buffer_alloc(sp2500->udev, count, GFP_KERNEL, &urb->transfer_dma);
> if (!buf) {
> retval = -ENOMEM;
> goto error;
> }
>
> if (code < 0 || code >= MAX_FF)
> return -EINVAL;
>
> buf[0]=0x51;
> buf[1]=(__u8)code;
>
> if (value > 0)
> buf[2]=02; //play
> else
> buf[2]=01; //stop
>
> buf[3]=01;
> count=4;
>
> usb_fill_int_urb(urb, sp2500->udev,
> usb_sndintpipe(sp2500->udev, sp2500->int_out_endpointAddr),
> buf, count, SP2500_write_int_callback, sp2500, 20);
> urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
>
>
> retval = usb_submit_urb(urb, GFP_KERNEL);
> if (retval) {
> err("%s - failed submitting write urb, error %d", __FUNCTION__, retval);
> goto error;
> }
>
> usb_free_urb(urb);
>
> return 0;
>
> error:
> err ("playback error");
> usb_buffer_free(sp2500->udev, count, buf, urb->transfer_dma);
> usb_free_urb(urb);
> return retval;
> }
Is following my replacement for this function correct? Mainly, I want
to know, if data packet is formed correctly.
> static int stff_play(struct input_dev *idev, int code, int value)
> {
> struct hid_device *hid = input_get_drvdata(idev);
> struct list_head *report_list = &hid->report_enum[HID_OUTPUT_REPORT].report_list;
> struct hid_report *report = list_entry(report_list->next, struct hid_report, list);
>
> report->field[0]->value[0] = 0x51;
> report->field[0]->value[1] = (__u8)code;
>
> if (value > 0)
> report->field[0]->value[2] = 02; //play
> else
> report->field[0]->value[2] = 01; //stop
>
> report->field[0]->value[3]=01;
>
> usbhid_submit_report(hid, report, USB_DIR_OUT);
>
> return 0;
> }
P.S. you can find SP2500 driver source here:
http://www.goffi.org/index.php?post/2006/09/14/Pilote-Linux-pour-le-joypad-Saitek-P2501
P.P.S. original driver contains quirk from original saitek driver --
d-pad and first analog stick swap on button press; I don't wan't to
implement this quirk at the moment
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