> So let me see if I understand correctly (let me know yes or no on each):
> 1. You do not have documentation which tells what reports are available on
> the device.
Yes . documentation tells only that data payload will come in form
<Report ID> <Payload>
No documentation is there to tell what reports are available on device .
> 2. The number and size of reports is listed in the HID descriptor, which you
> do not want to parse in userspace. You want the kernel to do it for you
> (which is a reasonable request, as modules like hiddev already do this kind
> of parsing).
Yes . its better if kernel do it it . otherwise each application
utilising hidraw
interface will have to maintain its own parser to get this minimum information
regarding No of reports and their len .
if kernel provides this minimum info , hidraw offers a very convinient
interface to communicate with a hid device using standard
open/read/write/ioctl system calls.
and its very useful for applications which are interested in getting
raw events only from device
without dwelling much deeper into the complexities of hid specs .
> 3. You want to be able to support the future releases where the report sizes
> may change.
>
Yes. definately it is required .
> I think I'm finally getting the picture. Again, tell me yes or no on each:
> 0. You're using HID device with User-Defined data.
Yes . the device data is mostly in the form of <command > < response > .
> 1. Your device has lots of reports, which all take the same type of data.
Yes . the device has lots of inputs and output reports .
the report values are <command > < response> only .
> 2. Each report differs _only_ in its length, but the data is the same. For
> example:
> 1. If you want to send 5 bytes to the device, you use report 1, which
> is 5 bytes long
> 2. If you want to send 10 bytes to the device, you use report 2,
> which is 10 bytes long.
> 3. if you want to send 20 bytes to the device, you use report 3,
> which is 20 bytes long.
> etc.
Yes. exactly . data payload len is the defining parameter to
determine the report N to use .
> 4. You want to know dynamically, which report you need to use, based on the
> payload length, because
> 4a. the only difference in your reports is the payload length.
>
Yes . Report selection should be dynamic .
> Might I ask what kind of device this is that behaves this way?
>
it is Ipod . i am enclosing report_descriptor and lsusb files for the same .
> For a device which uses numbered reports, the input report ID is always
> returned to read(). It's already doing what you're asking for.
>
it is ok . read() calls returns < report id > .
> read() is going to return one report per call to read(). It's not a stream
> interface. If your data is split across multiple reports, you'll need to
> stitch it back together on your end.
>
>
yes . i agree .
Thanx & Regards
Amit Nagal
Bus 002 Device 002: ID 05ac:1261 Apple, Inc. iPod Classic
Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 2.00
bDeviceClass 0 (Defined at Interface level)
bDeviceSubClass 0
bDeviceProtocol 0
bMaxPacketSize0 64
idVendor 0x05ac Apple, Inc.
idProduct 0x1261 iPod Classic
bcdDevice 0.01
iManufacturer 1 Apple Inc.
iProduct 2 iPod
iSerial 3 000A270013A06238
bNumConfigurations 2
Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 32
bNumInterfaces 1
bConfigurationValue 1
iConfiguration 0
bmAttributes 0xc0
Self Powered
MaxPower 500mA
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 0
bNumEndpoints 2
bInterfaceClass 8 Mass Storage
bInterfaceSubClass 6 SCSI
bInterfaceProtocol 80 Bulk (Zip)
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x83 EP 3 IN
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0200 1x 512 bytes
bInterval 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x02 EP 2 OUT
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0200 1x 512 bytes
bInterval 0
Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 149
bNumInterfaces 3
bConfigurationValue 2
iConfiguration 4 iPod USB Interface
bmAttributes 0xc0
Self Powered
MaxPower 500mA
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 0
bNumEndpoints 0
bInterfaceClass 1 Audio
bInterfaceSubClass 1 Control Device
bInterfaceProtocol 0
iInterface 0
AudioControl Interface Descriptor:
bLength 9
bDescriptorType 36
bDescriptorSubtype 1 (HEADER)
bcdADC 1.00
wTotalLength 30
bInCollection 1
baInterfaceNr( 0) 1
AudioControl Interface Descriptor:
bLength 12
bDescriptorType 36
bDescriptorSubtype 2 (INPUT_TERMINAL)
bTerminalID 1
wTerminalType 0x0201 Microphone
bAssocTerminal 2
bNrChannels 2
wChannelConfig 0x0003
Left Front (L)
Right Front (R)
iChannelNames 0
iTerminal 0
AudioControl Interface Descriptor:
bLength 9
bDescriptorType 36
bDescriptorSubtype 3 (OUTPUT_TERMINAL)
bTerminalID 2
wTerminalType 0x0101 USB Streaming
bAssocTerminal 1
bSourceID 1
iTerminal 0
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 1
bAlternateSetting 0
bNumEndpoints 0
bInterfaceClass 1 Audio
bInterfaceSubClass 2 Streaming
bInterfaceProtocol 0
iInterface 0
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 1
bAlternateSetting 1
bNumEndpoints 1
bInterfaceClass 1 Audio
bInterfaceSubClass 2 Streaming
bInterfaceProtocol 0
iInterface 0
AudioStreaming Interface Descriptor:
bLength 7
bDescriptorType 36
bDescriptorSubtype 1 (AS_GENERAL)
bTerminalLink 2
bDelay 1 frames
wFormatTag 1 PCM
AudioStreaming Interface Descriptor:
bLength 35
bDescriptorType 36
bDescriptorSubtype 2 (FORMAT_TYPE)
bFormatType 1 (FORMAT_TYPE_I)
bNrChannels 2
bSubframeSize 2
bBitResolution 16
bSamFreqType 9 Discrete
tSamFreq[ 0] 8000
tSamFreq[ 1] 11025
tSamFreq[ 2] 12000
tSamFreq[ 3] 16000
tSamFreq[ 4] 22050
tSamFreq[ 5] 24000
tSamFreq[ 6] 32000
tSamFreq[ 7] 44100
tSamFreq[ 8] 48000
Endpoint Descriptor:
bLength 9
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 1
Transfer Type Isochronous
Synch Type None
Usage Type Data
wMaxPacketSize 0x00c0 1x 192 bytes
bInterval 4
bRefresh 0
bSynchAddress 0
AudioControl Endpoint Descriptor:
bLength 7
bDescriptorType 37
bDescriptorSubtype 1 (EP_GENERAL)
bmAttributes 0x01
Sampling Frequency
bLockDelayUnits 0 Undefined
wLockDelay 0 Undefined
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 2
bAlternateSetting 0
bNumEndpoints 1
bInterfaceClass 3 Human Interface Device
bInterfaceSubClass 0 No Subclass
bInterfaceProtocol 0 None
iInterface 0
HID Device Descriptor:
bLength 9
bDescriptorType 33
bcdHID 1.01
bCountryCode 0 Not supported
bNumDescriptors 1
bDescriptorType 34 Report
wDescriptorLength 208
Report Descriptors:
** UNAVAILABLE **
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x83 EP 3 IN
bmAttributes 3
Transfer Type Interrupt
Synch Type None
Usage Type Data
wMaxPacketSize 0x0040 1x 64 bytes
bInterval 1
Device Qualifier (for other device speed):
bLength 10
bDescriptorType 6
bcdUSB 2.00
bDeviceClass 0 (Defined at Interface level)
bDeviceSubClass 0
bDeviceProtocol 0
bMaxPacketSize0 64
bNumConfigurations 2
Device Status: 0x0000
(Bus Powered)report descriptor (size 208, read 208) =
06 00 ff 09 01 a1 01 75 08 26 80 00 15 00 09 01 85 01 95 05 82 02 01 09 01 85 02
95 09 82 02 01 09 01 85 03 95 0d 82 02 01 09 01 85 04 95 11 82 02 01 09 01 85 05
95 19 82 02 01 09 01 85 06 95 31 82 02 01 09 01 85 07 95 5f 82 02 01 09 01 85 08
95 c1 82 02 01 09 01 85 09 96 01 01 82 02 01 09 01 85 0a 96 81 01 82 02 01 09 01
85 0b 96 01 02 82 02 01 09 01 85 0c 96 ff 02 82 02 01 09 01 85 0d 95 05 92 02 01
09 01 85 0e 95 09 92 02 01 09 01 85 0f 95 0d 92 02 01 09 01 85 10 95 11 92 02 01
09 01 85 11 95 19 92 02 01 09 01 85 12 95 31 92 02 01 09 01 85 13 95 5f 92 02 01
09 01 85 14 95 c1 92 02 01 09 01 85 15 95 ff 92 02 01 c0
=====>[IPOD HID ]detailed :
06 00 ff //vendor defined usage page
09 01 //vendor usage 1
a1 01 //collection applicator
75 08 //report size
26 80 00 //logical maximum
15 00 //logical minimum
//vendor usage -id (2 bytes ) , report id (2 bytes ) , report count (2/3 bytes ) , i/p or o/p report (3 bytes )
09 01 85 01 95 05 82 02 01
09 01 85 02 95 09 82 02 01
09 01 85 03 95 0d 82 02 01
09 01 85 04 95 11 82 02 01
09 01 85 05 95 19 82 02 01
09 01 85 06 95 31 82 02 01
09 01 85 07 95 5f 82 02 01
09 01 85 08 95 c1 82 02 01
09 01 85 09 96 01 01 82 02 01
09 01 85 0a 96 81 01 82 02 01
09 01 85 0b 96 01 02 82 02 01
09 01 85 0c 96 ff 02 82 02 01
09 01 85 0d 95 05 92 02 01
09 01 85 0e 95 09 92 02 01
09 01 85 0f 95 0d 92 02 01
09 01 85 10 95 11 92 02 01
09 01 85 11 95 19 92 02 01
09 01 85 12 95 31 92 02 01
09 01 85 13 95 5f 92 02 01
09 01 85 14 95 c1 92 02 01
09 01 85 15 95 ff 92 02 01
c0 //end of collection
