[haiku-gsoc] Re: Issues in the USB Stack
- From: Jérôme Duval <jerome.duval@xxxxxxxxx>
- To: haiku-gsoc@xxxxxxxxxxxxx
- Date: Wed, 6 Aug 2014 18:54:21 +0200
2014-08-06 7:34 GMT+02:00 Akshay Jaggi <akshay1994.leo@xxxxxxxxx>:
> I greped for device_address in libusb code. Yes, its basically for
> information purposes only, though it might be used by some programs to take
> device input from user (for example libusb/examples/fxload.c). But then
> again, they also have the usual method of vid:pid.
> Just to satisfy the requirement, I can add the integers in path of device
> file descriptor, and store that value here.
We could eventually add a more generic B_USB_RAW_COMMAND_GET_PROPERTY.
>
> This IOCTL only handles usb_generic_descriptor. You should probably
>
>
> Don't we have B_USB_RAW_COMMAND_GET_GENERIC_DESCRIPTOR for generic
> descriptors?
Sure, it's just wTotalLength isn't generic, it's only usable for
configuration descriptors.
>
> use B_USB_RAW_COMMAND_GET_CONFIGURATION_DESCRIPTOR instead, and patch
> it to use "total_length":
> * if the provided buffer is exactly the size of
> usb_configuration_descriptor, then just copy that length and return
> OK.
> * if the provided buffer is bigger but too small, then copy that
> length and return B_BUFFER_OVERFLOW.
> The USBKit can eventually be extended later.
>
>
> We do not get the size of the buffer in
> B_USB_RAW_COMMAND_GET_CONFIGURATION_DESCRIPTOR. We have this information in
> B_USB_RAW_COMMAND_GET_DESCRIPTOR.
You mean the command descriptor buffer? The size of the descriptor is
in the descriptor itself.
As I wrote, retrieving the full configuration descriptor would require
two calls, one to get the standard part "length", one for the total
length.
Bye,
Jérôme
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