Hi, On 06/29/2012 04:18 PM, Alan Stern wrote: <snip>
Okay. Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Too soon. As said I still needed to test the patch with isoc devices, and it failed. It turns out most controllers don't handle urb->sg for isoc transfers! I've checked the ehci code, and it certainly does not. If you look at ehci-sched.c: itd_sched_init() it unconditionally uses urb->transfer_dma. I've not checked the xhci code, but I got similar (non working) results during testing there. This may very well be by design, but when writing the devio.c patch I thought it would be best to split all large-ish transfers, abnd that turns out to not be a good idea :) This is not really a problem since large isoc urbs can easily be split by userspace by simply using less iso-packets / urb, without any of the issues we've seen with bulk transfer splitting. And likewise there are no kernel drivers needing sg support for isoc transfers. We may want to add a BUG_ON urb->sg being set for isoc transfers somewhere though, in case a driver author ever does decide to try and use sg there, like I did :) So I'm sending a new version of the patchset, where the use of scatterlists is limited to bulk transfers (just a small change really). This new version also addresses / changes: -making the caps ioctl parameter u32 instead of u64 -a missing "totlen -= u;" statement in the loop allocating the per sg entry buffers, causing the last buffer to always be USB_SG_SIZE, even if a smaller buffer would suffice Regards, Hans -- 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
