On Feb 13, Stanislaw Gruszka wrote: > On Tue, Feb 12, 2019 at 11:09:03PM +0100, Lorenzo Bianconi wrote: > > > > On Tue, Feb 12, 2019 at 04:08:37PM +0100, Lorenzo Bianconi wrote: > > > > > > > > What unnecessary operation ? > > > > > > > > > > > > > > the ones in mt76u_fill_bulk_urb() > > > > > > > > > > > > Your patches also add extra operations on hotpath due to > > > > > > urb->num_sgs and > > > > > > dev->usb.sg_en checks. > > > > > > > > > > here I guess you should use mt76u_check_sg() instead of > > > > > udev->bus->sg_tablesize > 0 so I think you need to precompute it > > > > > since it is in > > > > > the hotpath > > > > > > > > It's not necessary. If udev->bus->sg_tablesize > 0 is true and rest > > > > of mt76u_check_sg() is not, we will submit urb with urb->num_sgs = 1 to > > > > usb host driver, what is fine. > > > > > > > > > Moreover the RFC series has been tested by multiple users and on > > > > > multiple > > > > > devices > > > > > > > > I know. Perhaps you could test my patch on rpi ? > > > > > > sure, I will do it later > > > > I confirm that even with Stanislaw's patch the usb dongle is properly > > working > > on rpi3+ > > Thanks for testing. Would be ok to you to post my patch against > wireless-drivers tree and cc stable as fix for non-SG usb hosts, > drop your set for -next and work for fix for SG issue on AMD IOMMU?
I agree that your patch works (since it does not use SG I/O :)) but I think it is more clear (and manageable) to have two separated routines for memory allocation. Moreover I think that this check has to be done in the control plane instead of the data plane, so I would like to spend some more time in order to see if it is possible to remove some checks in the hot-path Regards, Lorenzo > > Stanislaw
