On Tuesday 04 April 2006 11:47 pm, rakesh kn wrote: > How does the Test 3 and Test 4 work.? Please tell how the "vary" > paramter helps. Is it to vary the transfer_buffer_length in URB , in > each iteration.by the number specified in parameter "vary".
If you read the source code, that is indeed what it does. Also see http://www.linux-usb.org/usbtest/test.sh for a set of test cases which use the "vary" parameter to ensure a fair number of important edge cases get test coverage. > Can u please explain the use of "Scatter-Gather list". What i > understand is that the URB->transfer_bufffer is divided in to a > scatter list , which are pointers to buffer. This is "Scatter Gather > DMA ", but the DMA controller should be supporting this. So your confusion is ... ? See linux/drivers/usb/core/message.c to see what usb_sg_wait() does ... and observe how it's not submitting just one URB at a time, but constructs a queue of several. Which boils down to an arbitrarily deep DMA queue (which the driver and hardware don't just "automagically get right") with all sorts of funky boundary conditions (ditto). Yes, all that "should" work... > Can u please point out , how can a EHCI -HCD driver be divided into > various modules .. like IRQ Handling, URB QUEING... ETC . "ls linux/drivers/usb/host/ehci*c" shows one such breakdown. > Which modules in ehci-hcd does the above test affect. The bulk tests (1-8) cover the bulk queueing in ehci-q.c, along with its interaction with IRQ handling. On some hardware, running those tests in stress test mode (leave them running for a week) have also shaken out silicon bugs, like the EHCI controller wrongly writing back overlay regions in the queue heads in certain cases. In other cases, such issues show up better with drivers like usb-storage. - Dave ------------------------------------------------------- This SF.Net email is sponsored by xPML, a groundbreaking scripting language that extends applications into web and mobile media. Attend the live webcast and join the prime developer group breaking into this new coding territory! http://sel.as-us.falkag.net/sel?cmd=lnk&kid=110944&bid=241720&dat=121642 _______________________________________________ [email protected] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
