Re: [RFC v2 1/1] HID: User-space I/O driver support for HID subsystem

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Hi Nicolas

On Wed, Mar 28, 2012 at 1:15 PM, Nicolas Pouillon <npouillon@xxxxxxxxxx> wrote:
> David,
>
> ----- Original Message -----
>
>> >> +     strncpy(hid->name, ev->u.create.name, 128);
>> >> +     hid->name[127] = 0;
>> >> +     hid->ll_driver = &uhid_hid_driver;
>> >> +     hid->hid_get_raw_report = uhid_hid_get_raw;
>> >> +     hid->hid_output_raw_report = uhid_hid_output_raw;
>> >> +     hid->bus = ev->u.create.bus;
>> >> +     hid->vendor = ev->u.create.vendor;
>> >> +     hid->product = ev->u.create.product;
>> >> +     hid->version = ev->u.create.version;
>> >> +     hid->country = ev->u.create.country;
>> >> +     hid->phys[0] = 0;
>> >> +     hid->uniq[0] = 0;
>> >> +     hid->driver_data = uhid;
>> >> +     hid->dev.parent = uhid->parent;
>> >
>> > Here we have to make sure that we have all required information provided
>> > by userspace. Anything else that HID might require to work better. Or
>> > that BR/EDR or LE provides additionally over USB.
>>
>> Beside phys and uniq I have copied all information that HIDP and
>> USBHID use. I haven't found any other field that could be of interest
>> here. We can also always add UHID_CREATE2 with additional fields to
>> allow further additions (or use a "size" field as you suggested
>> below).
>
> HID report descriptor may reference Physical Descriptor (HID 6.2.3) and
> String Descriptor entries (USB 9.6.8, HID E.11).  Physical Descriptor
> blob could be another __user buffer + size in uhid_create_req.  String
> descriptor should probably be an event for querying strings.

I haven't seen that hid-core uses them? I pass the report-descriptor
to hid_parse_report() and I don't see a way to pass in the phys-desc
or string-descriptors. Neither USBHID nor HIDP uses them or am I
missing something here?
Anyway, we can always add them with a UHID_CREATE_EXT or similar
command later if hid-core adds support for them.

> hidraw interface also offers access to Feature Reports, adding events
> to send/receive and query (kernel querying uhid client) feature reports
> could be of some interest.

Yeah, I haven't implemented this (yet) and I return -EOPNOTSUPP.
However, it's on my TODO list. Thanks!

> Cheers,
> --
> Nicolas Pouillon

Thanks
David
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