Re: [PATCH v2 6/6] HID: uclogic: actually invert the in-range bit for huion tablets only

[Nikolai Kondrashov]

On 03/03/2015 12:25 AM, Benjamin Tissoires wrote:
> On Feb 28 2015 or thereabouts, Nikolai Kondrashov wrote:
> > On 02/26/2015 08:57 PM, Benjamin Tissoires wrote:
> > > This hack is only needed for Huion tablets. It does not seem to have
> > > any effect on the other tablets handled by this device right now, but
> > > it's better to check for the product id sooner than discovering that
> > > we have messed up one tablet later.
> > >
> > > Signed-off-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx>
> > > ---
> > >
> > > New in v2
> > >
> > >   drivers/hid/hid-uclogic.c | 3 ++-
> > >   1 file changed, 2 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/hid/hid-uclogic.c b/drivers/hid/hid-uclogic.c
> > > index f44e72b..5f5c16e 100644
> > > --- a/drivers/hid/hid-uclogic.c
> > > +++ b/drivers/hid/hid-uclogic.c
> > > @@ -930,7 +930,8 @@ static int uclogic_raw_event(struct hid_device *hdev, struct hid_report *report,
> > >   	struct usb_interface *intf = to_usb_interface(hdev->dev.parent);
> > >
> > >   	/* If this is a pen input report */
> > > -	if (intf->cur_altsetting->desc.bInterfaceNumber == 0 &&
> > > +	if (hdev->product == USB_DEVICE_ID_HUION_TABLET &&
> > > +	    intf->cur_altsetting->desc.bInterfaceNumber == 0 &&
> > >   	    report->type == HID_INPUT_REPORT &&
> > >   	    report->id == 0x07 && size >= 2)
> > >   		/* Invert the in-range bit */
> >
> > Right, I completely forgot about this. That's why it's important to put these
> > things out for testing.
>
> yes, and no. A thorough review can help detect these while it's a pain
> to ask each and every users to test every possible device :)

Perhaps :)

> > However, this should be inverted not just for Huion tablets, but rather for
> > all "enabled" tablets. The UC-Logic TWHA60 v3 inverts that bit as well when
> > enabled, IIRC. We can filter enabled tablets by drvdata->rdesc != NULL, or add
> > an explicit flag.
>
> I like the flag. It will remove the dependency to usb in raw_event()
> which is always a plus.

Great!

> Speaking of which. I started looking at these dependencies in the hid
> subtree (like every year, in spring, these dependencies itches me).
> I think we can find a preventive solution which would allow to reinject
> through uhid any device even if the driver wants to talk to the usb
> layer. This will require some more effort on my side but will allow us
> to have at least some regressions tests in hid-uclogic too.

This sounds good. I was thinking about record/replay on HID level over uhid,
similar to evdev level, but as usual didn't have time to even think it through
(it's not my day job).

Nick
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/