Re: [PATCH] HID: Add Support for Setting and Getting Feature Reports from hidraw

[Alan Ott]

On 06/08/2010 02:32 AM, Antonio Ospite wrote:
> On Mon,  7 Jun 2010 23:51:48 -0400
> Alan Ott<alan@xxxxxxxxxxx>  wrote:
>
>    
> > Per the HID Specification, Feature reports must be sent and received on
> > the Configuration endpoint (EP 0) through the Set_Report/Get_Report
> > interfaces.  This patch adds two ioctls to hidraw to set and get feature
> > reports to and from the device.  Modifications were made to hidraw and
> > usbhid.
> >
> > New hidraw ioctls:
> >    HIDIOCSFEATURE - Perform a Set_Report transfer of a Feature report.
> >    HIDIOCGFEATURE - Perform a Get_Report transfer of a Feature report.
> >
> > Signed-off-by: Alan Ott<alan@xxxxxxxxxxx>
> > ---
> >      
> Thanks Alan, I am going to test this quite soon.
>
> TBH, when I was thinking about how to extend hidraw I thought we could
> have added a new report_type field to struct hidraw_report_descriptor,
> in order to re-use the HIDIOCGRDESC ioctl handler itself, adding then a
> HIDIOCSRDESC for setting the report. This looked cleaner to my eyes,
>    
Thanks for the feedback, Antonio. The HIDIOCGRDESC ioctl copies the 
existing descriptor from the hid_device structure. Since it does not 
initiate a Get_Report transfer, I'm not sure how much re-use there could 
have been using that method. In my estimation, a Set_Report/Get_Report 
was more similar to the call to write().

> but I didn't actually implement this, so I don't know if it was
> feasible, for instance one problem I didn't investigate further was
> about the default value of the aforementioned report_type field in
> order to keep the current behavior of HIDIOCGRDESC.
>    
I'm not sure what you mean here, as the report_type field is not part of 
hidraw_report_descriptor.

Thanks for testing my patch. Please let me know if you have problems 
with it.

Alan.

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