On Wed, 18 Nov 2009, Simon Arlott wrote: > Can anyone explain this speed difference I'm seeing with usb_bulk_msg()? > > Increasing the size of the data doesn't improve the speed at all. This > makes firmware loading take significantly longer with OHCI. > > I've tested this with two UHCI controllers, two OHCI controllers, and > two different versions of the device. Even on the same system with the > same device the speed difference occurs between OHCI and UHCI. > > I've added a debug line to drivers/usb/atm/cxacru.c in cxacru_fw(), > which uploads the firmware in PAGE_SIZE chunks: > + printk(KERN_INFO "cxacru: sending fw %#x size %#x to %#x", fw, offb, offd); > ret = usb_bulk_msg(usb_dev, usb_sndbulkpipe(usb_dev, CXACRU_EP_CMD), > > > With OHCI and PAGE_SIZE chunks (4KB): > [2567188.504299] cxacru: sending fw 0x3 size 0x1000 to 0xe00 > [2567188.760293] cxacru: sending fw 0x3 size 0x1000 to 0x1c00 > [2567189.016258] cxacru: sending fw 0x3 size 0x1000 to 0x2a00 > [2567189.272235] cxacru: sending fw 0x3 size 0x1000 to 0x3800 > [2567189.528210] cxacru: sending fw 0x3 size 0x1000 to 0x4600 > [2567189.784488] cxacru: sending fw 0x3 size 0x1000 to 0x5400 > ... > [2567233.044134] cxacru: sending fw 0x3 size 0x2c0 to 0x98668 ... > With OHCI and PAGE_SIZE*8 chunks (32KB): > [ 4731.826738] cxacru: sending fw 0x3 size 0x8000 to 0x7000 > [ 4733.874628] cxacru: sending fw 0x3 size 0x8000 to 0xe000 > [ 4735.922353] cxacru: sending fw 0x3 size 0x8000 to 0x15000 > [ 4737.970153] cxacru: sending fw 0x3 size 0x8000 to 0x1c000 > [ 4740.017937] cxacru: sending fw 0x3 size 0x8000 to 0x23000 > [ 4742.065814] cxacru: sending fw 0x3 size 0x8000 to 0x2a000 > ... > [ 4774.830569] cxacru: sending fw 0x3 size 0x62c0 to #98668 Each OHCI transfer requires about 256 ms per 4-KB page. There's no obvious reason for this to take so long. I'd guess it was caused by a hardware problem except that you say the same thing happened with two different controllers. Were they both on the same computer? You may have to do a bisection search to find the answer. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
