From: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
To: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Felix Fietkau <nbd@nbd.name>,
Stefan Wahren <stefan.wahren@i2se.com>,
Alan Stern <stern@rowland.harvard.edu>,
Doug Anderson <dianders@chromium.org>,
Minas Harutyunyan <hminas@synopsys.com>,
USB list <linux-usb@vger.kernel.org>,
linux-wireless <linux-wireless@vger.kernel.org>
Subject: Re: [BUG] mt76x0u: Probing issues on Raspberry Pi 3 B+
Date: Wed, 20 Feb 2019 17:36:10 +0100 [thread overview]
Message-ID: <20190220163609.GI2626@localhost.localdomain> (raw)
In-Reply-To: <20190220163229.GB14165@redhat.com>
> On Wed, Feb 20, 2019 at 05:22:18PM +0100, Lorenzo Bianconi wrote:
> > > On Wed, Feb 20, 2019 at 02:22:08PM +0100, Lorenzo Bianconi wrote:
> > > > > On Tue, Feb 19, 2019 at 01:19:26PM +0100, Felix Fietkau wrote:
> > > > > > >> >> The way I see it, we have two choices.
> > > > > > >> >> 1. Fix dwc2 to do its alignment quirk for the urb->sg != NULL case
> > > > > > >> >> 2. Rely on urb->transfer_buffer and keep urb->sg NULL
> > > > > > >> >
> > > > > > >> > I agree, if this is only needed for dwc2. Though I would investigate
> > > > > > >> > if this is not a bug on other platforms as well.
> > > > > > >> >From what I can see, using Lorenzo's patches seems to be the better
> > > > > > >> solution, since they avoid these corner cases in dwc2 (and maybe other
> > > > > > >> drivers as well). I will apply them and then we'll see if we need to do
> > > > > > >> any further improvements later on.
> > > > > > >
> > > > > > > They work on rpi dwc2, but they do not address root of the problem.
> > > > > > > There is clearly something wrong how mt76usb handle SG, what is not
> > > > > > > fixed. And adding disable_usb_sg module parameter for hcd's supporting
> > > > > > > SG should be red flag.
> > > > > > I think we're simply dealing with multiple issues here, only some of
> > > > > > which are fixed by Lorenzo's patches.
> > > > > > I'm pretty sure it's still wrong for mt76 to try to align its buffers,
> > > > > > since the Linux USB API supports non-aligned transfer buffers and it
> > > > > > should be up to the controller driver to deal with that.
> > > > >
> > > > > Agree.
> > > > >
> > > > > > dwc2 tries to do that, but that has limitations which I already pointed
> > > > > > out and which are properly dealt with by Lorenzo's patches.
> > > > >
> > > > > I planed to just accept current solution, but I started to work on patch
> > > > > that remove len, sglen arguments from mt76u_buf_alloc() and use
> > > > > q->buf_size and SKB_WITH_OVERHEAD(q->buf_size) directly and realized how
> > > > > related code is now tangled.
> > > > >
> > > > > Would be ok to send this patch with proper changelog as fix for RPI
> > > > > against wireless-drivers and cc:stable (assuming it works and really
> > > > > fix things on RPI) and revert Lorenzo's patches in -next ?
> > > >
> > > > Hi Stanislaw,
> > > >
> > > > what is the advantage of doing so?
> > > To have small fix proper for -stable to fix the problem in 4.20 and 4.19,
> > > and have simpler code.
> >
> > merging the series I sent we will have a pretty simple approach, just a
> > single routine that allocates the rx buffers in the control path according to
> > the operating mode.
>
> So will you do the backport of your patches and post them to -stable ?
> Do you think greg-kh will accept those ?
I will take care of it
Regards,
Lorenzo
>
> Stanislaw
next prev parent reply other threads:[~2019-02-20 16:36 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20190211173315.GE6292@redhat.com>
[not found] ` <Pine.LNX.4.44L0.1902111246410.1543-100000@iolanthe.rowland.org>
2019-02-12 0:06 ` [BUG] mt76x0u: Probing issues on Raspberry Pi 3 B+ Lorenzo Bianconi
2019-02-12 9:30 ` Stanislaw Gruszka
2019-02-12 11:58 ` Lorenzo Bianconi
2019-02-12 13:15 ` Stanislaw Gruszka
2019-02-14 6:49 ` Stefan Wahren
2019-02-14 9:25 ` Stanislaw Gruszka
2019-02-14 9:48 ` Stefan Wahren
2019-02-14 9:54 ` Stanislaw Gruszka
2019-02-15 7:12 ` Stanislaw Gruszka
2019-02-16 11:05 ` Stefan Wahren
2019-02-16 14:07 ` Stanislaw Gruszka
2019-02-16 19:17 ` Stefan Wahren
2019-02-18 13:52 ` Stanislaw Gruszka
2019-02-18 14:25 ` Lorenzo Bianconi
2019-02-18 14:47 ` Stanislaw Gruszka
2019-02-18 14:43 ` Felix Fietkau
2019-02-18 15:03 ` Stanislaw Gruszka
2019-02-18 18:52 ` Felix Fietkau
2019-02-19 10:42 ` Stanislaw Gruszka
2019-02-19 12:19 ` Felix Fietkau
2019-02-20 13:00 ` Stanislaw Gruszka
2019-02-20 13:22 ` Lorenzo Bianconi
2019-02-20 16:14 ` Stanislaw Gruszka
2019-02-20 16:22 ` Lorenzo Bianconi
2019-02-20 16:32 ` Stanislaw Gruszka
2019-02-20 16:36 ` Lorenzo Bianconi [this message]
2019-03-03 21:16 ` Stefan Wahren
2019-02-18 22:19 ` Stefan Wahren
2019-02-19 10:59 ` Stanislaw Gruszka
2019-02-19 12:11 ` Felix Fietkau
2019-02-19 15:40 ` Alan Stern
2019-02-20 10:20 ` Stanislaw Gruszka
2019-02-20 15:25 ` Alan Stern
2019-02-19 17:02 ` Stefan Wahren
2019-02-12 15:27 ` Alan Stern
2019-02-09 12:08 Stefan Wahren
2019-02-09 18:46 ` Lorenzo Bianconi
2019-02-09 20:29 ` Stefan Wahren
2019-02-09 20:33 ` Lorenzo Bianconi
2019-02-09 22:47 ` Stefan Wahren
2019-02-10 9:41 ` Stanislaw Gruszka
2019-02-10 10:22 ` Lorenzo Bianconi
2019-02-11 7:44 ` Stanislaw Gruszka
2019-02-11 10:04 ` Lorenzo Bianconi
2019-02-11 10:33 ` Stefan Wahren
2019-02-11 11:06 ` Lorenzo Bianconi
2019-02-11 14:04 ` Stefan Wahren
2019-02-11 15:10 ` Lorenzo Bianconi
2019-02-11 15:27 ` Stefan Wahren
2019-02-11 15:57 ` Lorenzo Bianconi
2019-02-13 7:05 ` Stefan Wahren
2019-02-11 17:22 ` Stanislaw Gruszka
2019-02-10 9:29 ` Stanislaw Gruszka
2019-02-10 16:38 ` Stefan Wahren
2019-02-10 16:52 ` Lorenzo Bianconi
2019-02-10 17:39 ` Lorenzo Bianconi
2019-02-11 7:50 ` Stanislaw Gruszka
2019-02-11 8:08 ` Stefan Wahren
2019-02-11 9:52 ` Lorenzo Bianconi
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