From mboxrd@z Thu Jan 1 00:00:00 1970 From: Amit Nagal Subject: Re: Report ID problem with HID-RAW interface usage Date: Fri, 2 Jul 2010 09:19:59 -0700 Message-ID: References: <4C2A1FA0.6020704@signal11.us> <4C2B3E6B.7060703@signal11.us> <16645BD8-07BB-4189-8A69-18E5EC76E670@signal11.us> <4C2E0057.30206@signal11.us> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Return-path: In-Reply-To: <4C2E0057.30206-yzvJWuRpmD1zbRFIqnYvSA@public.gmane.org> Sender: linux-usb-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Alan Ott Cc: Jiri Kosina , linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-input-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Antonio Ospite , Xiaofan Chen List-Id: linux-input@vger.kernel.org > I'm going to challenge this. I looked at the report descriptor you attached, > and I don't think it really works the way you think it does. What it looks > like to me is separate reports expecting separate data, not a bunch of > reports all expecting the same data but of different lengths. What you > describe would be fairly non-standard, IMO. > Sorry , i did not get what is meant by "a bunch of reports all expecting same data but of different lengths " . what is the meaning of this phrase "same data" . ya i agree if the device supports separate reports , theoretically each one should be there to serve separate data . otherwise a device can define a report of max size N and all transactions can take place with it . but if a device support only one report of max size N the drawback is that even to send a very small report data (say 4-5 bytes ) , we have to use max size N report always , which may waste considerable bandwidth . Now in my case yes mostly different reports carry different data only . as i told previously , the payload protocol is in the form . by this i mean let say if i want to fetch ipod root folder entries (filenames ), i will send a command for that in a output report and device will send root folder entries in input reports . so different payload commands are send over different reports only . But again , the defining parameter that a report N should be used is data payload len only . so if 2 payload commands have same size , both can be send using same report ID . and this thing is already working for me . > What I would suggest for the short-term is this: > With the device you have, send data based on the HID descriptor you attached > to the last email. I mean manually. In the case of your descriptor: if the > report length you want to send is <= 5, use report 1; If it's <= 9, use > report 2; if it's <= 13, use report 3; if it's <= 17, use report 4; if it's > <= 25, use report 5, etc. > Yes , this approach is already working for me . with the above mentioned approch ( <= 5 use report 1 , <=9 use report 2) and using hidraw interface , i am able to transact a few basic payload commands with the device . infact even the device is sending different payload command using the same < Report ID > . May be i am wrong , due to lack of documentation regarding the presence of different report ID , but i am able to transact with the device using the above mentioned approach of sending payload data in a report whose size is >= data payload len . if desired , i can send dmesg logs also depicting the same . Thanx & Regards Amit Nagal -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html