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Re: Acquiring Dental RVG on Linux

On Sun, Dec 27, 2020 at 11:44:07AM +0530, Sonali Warunjikar wrote:

I realize all control transfers are to be handled using a different api
ctrl_transfer and wht usbmon is showing are nothing but its parameter
values. The following call works (first time ever something worked).

  dev.ctrl_transfer(0x80, 0x06, 0x0100, 0x0000, 0x0012)

Still have some questions like this. Request list members who can help to
please help:

1. As per [1] event type 'S' and 'C' are for Submission and Callback. Does
it clearly mean 'S' is 'from host' and 'C' is 'from device'?

2. URB direction is either 'i' or 'o'. Now, what is 'o' for a host is
'i' for a device and vice versa. So the same data packet can be identified
as 'S' 'Co' as well as 'C' 'Ci'? How is it decided by usbmon then?

For example, what is the difference between following pairs of
interactions 'S' 'Ci' - 'C' 'Ci' and 'S' 'Co' - 'C' 'Co'? Isn't the sense
of communication in back to back events same in both? So how is it decided
which pair is of 'Ci' and which of 'Co'?

1.022.000 S Ci 0012 80 06 0100 0000 0012
1.022.000 C Ci 0012 OK
                    12 01 00 02 ff ff ff 40 2b 08 0c 00 01 00 00 00 00 01

1.024.000 S Co 0000 40 81 0000 0000 0000
1.024.000 C Co 0000 OK

[1] https://www.kernel.org/doc/Documentation/usb/usbmon.txt

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