>
> (repost with corrected Lorenzo email)
>
> On Tue, Feb 12, 2019 at 02:45:50PM +0100, Stanislaw Gruszka wrote:
> > On Tue, Feb 12, 2019 at 02:24:47PM +0100, LorenzoBianconilorenzo@xxxxxxxxxx wrote:
> > > From: Lorenzo Bianconi <lorenzo@xxxxxxxxxx>
> > >
> > > Use linear fragment and not a single usb scatter-gather buffer in mt76u
> > > {tx,rx} datapath if the usb controller has sg data length constraints.
> > > Moreover add disable_usb_sg module parameter in order to explicitly
> > > disable scatter-gather. SG I/O is not supported by all host drivers and
> > > some users have reported sg issues on AMD IOMMU.
> >
> > Again. This is not right approach. SG issues should be fixed
> > not workarounded.
Hi Stanislaw,
here we do not use SG, so num_sg is 0 and we use transfer_buffer. I do
not see how I am working around the issue.
Moreover with this approach we avoid some unnecessary operation in the hotpath
Regards,
Lorenzo
> >
> > > This series has been tested on AMD IOMMU cpus/motherboards and on rpi3+
> >
> > > - rebased on top of 'fix multiple issues in mt76u error path'
> > > https://patchwork.kernel.org/cover/10804919/
> > >
> > > Lorenzo Bianconi (4):
> > > mt76: usb: move mt76u_check_sg in usb.c
> > > mt76: usb: do not use sg buffers for mcu messages
> > > mt76: usb: use a linear buffer for tx/rx datapath if sg is not
> > > supported
> > > mt76: usb: introduce disable_usb_sg parameter
> > >
> > > drivers/net/wireless/mediatek/mt76/mt76.h | 14 +-
> > > .../net/wireless/mediatek/mt76/mt76x0/usb.c | 2 +-
> > > .../wireless/mediatek/mt76/mt76x02_usb_mcu.c | 3 +-
> > > .../wireless/mediatek/mt76/mt76x2/usb_init.c | 2 +-
> > > drivers/net/wireless/mediatek/mt76/usb.c | 133 +++++++++++++-----
> > > drivers/net/wireless/mediatek/mt76/usb_mcu.c | 5 +-
> > > 6 files changed, 105 insertions(+), 54 deletions(-)
> >
> > I really think my approach is simpler. Diffstat from my proposed patch is:
> >
> > drivers/net/wireless/mediatek/mt76/mt76.h | 1 +
> > drivers/net/wireless/mediatek/mt76/usb.c | 55 ++++++++++++++---------
> > 2 files changed, 36 insertions(+), 20 deletions(-)
> >
> > Also this fix bug(s), presumably regression for mt76x0, should be
> > backported.
> >
> > Stanislaw
> >
