From: Stanislaw Gruszka <sgruszka@redhat.com>
To: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Cc: Felix Fietkau <nbd@nbd.name>,
linux-wireless <linux-wireless@vger.kernel.org>,
lorenzo@kernel.org
Subject: Re: [PATCH 0/4] do not use sg if not properly supported by usb controller
Date: Tue, 12 Feb 2019 15:17:25 +0100 [thread overview]
Message-ID: <20190212141725.GD12906@redhat.com> (raw)
In-Reply-To: <CAJ0CqmVhH61P1V1fmhicPXwA7vHjv+Hh7h2DYbci1uDRJCyENA@mail.gmail.com>
On Tue, Feb 12, 2019 at 03:09:53PM +0100, Lorenzo Bianconi wrote:
> >
> > (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@kernel.org wrote:
> > > > From: Lorenzo Bianconi <lorenzo@kernel.org>
> > > >
> > > > 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.
By avoiding SG buffer allocation and configuration which most likely
need to be fixed.
> Moreover with this approach we avoid some unnecessary operation in the hotpath
What unnecessary operation ?
Stanislaw
next prev parent reply other threads:[~2019-02-12 14:17 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-12 13:42 [PATCH RESEND 0/4] do not use sg if not properly supported by usb controller lorenzo
2019-02-12 13:42 ` [PATCH RESEND 1/4] mt76: usb: move mt76u_check_sg in usb.c lorenzo
2019-02-12 13:42 ` [PATCH RESEND 2/4] mt76: usb: do not use sg buffers for mcu messages lorenzo
2019-02-12 13:42 ` [PATCH RESEND 3/4] mt76: usb: use a linear buffer for tx/rx datapath if sg is not supported lorenzo
2019-02-12 13:42 ` [PATCH RESEND 4/4] mt76: usb: introduce disable_usb_sg parameter lorenzo
2019-02-12 13:45 ` [PATCH 0/4] do not use sg if not properly supported by usb controller Stanislaw Gruszka
2019-02-12 13:51 ` Stanislaw Gruszka
2019-02-12 14:09 ` Lorenzo Bianconi
2019-02-12 14:17 ` Stanislaw Gruszka [this message]
2019-02-12 14:25 ` Lorenzo Bianconi
2019-02-12 14:54 ` Stanislaw Gruszka
2019-02-12 15:08 ` Lorenzo Bianconi
2019-02-12 15:26 ` Stanislaw Gruszka
2019-02-12 15:50 ` Lorenzo Bianconi
2019-02-12 22:09 ` Lorenzo Bianconi
2019-02-13 9:44 ` Stanislaw Gruszka
2019-02-13 11:00 ` Lorenzo Bianconi
2019-02-13 11:59 ` Stanislaw Gruszka
2019-02-18 18:56 ` [PATCH RESEND " Felix Fietkau
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