Balaji Rao: USB Support Project


Week 2

June 8th

Commits : 5ce9d4fbf8a2a83622e0d396e47e61426a4a0169

Whole day spent in debugging and analysing “on-the-wire” USB data. The effort was really worthwhile. We're now able to obtain the device descriptor by querying the device. Below is a QEMU screenshot.

June 7th

Commits : a4e2572312450318358da5e32d3e8cad0cde379a

Added debugging routines that dump information about QH, TD, UHCI Host Controller and Root Hub ports. This has been very useful in debugging. The Host controller now to executes the schedule continuously. I was trying to send a Control Transaction to obtain the device descriptor of the device attached. But the TD of the SETUP packet is failing with a CRC/Timeout error. Looks like the device is not receiving the packet, probably because it did not receive a sufficiently long RESET on its port.

June 5th and 6th

Commits : 794c411c1ec236996f39ae607aac1a2166ecf64e, f8ced896bcd37046a4ac8919ed3f57480e1b94bf

Finished writing the support for sending control messages. Also complete is the code to retrieve the device descriptors. It is still buggy at the moment. I plan to fix it by tomorrow.

Prepared a document describing the design of the USB subsystem. Click here.

June 2nd

Began writing infrastructure to support sending of control messages to a devices. This enables us to talk to them and retrieve their device descriptors. A lot of progress is achieved once we're able to send control messages.

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