linux-wireless.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Stanislaw Gruszka <sgruszka@redhat.com>
To: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Cc: Alan Stern <stern@rowland.harvard.edu>,
	Stefan Wahren <stefan.wahren@i2se.com>,
	Felix Fietkau <nbd@nbd.name>,
	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: Tue, 12 Feb 2019 14:15:43 +0100	[thread overview]
Message-ID: <20190212131542.GC12906@redhat.com> (raw)
In-Reply-To: <20190212115842.GA24197@localhost.localdomain>

On Tue, Feb 12, 2019 at 12:58:43PM +0100, Lorenzo Bianconi wrote:
> > +	usb_fill_bulk_urb(buf->urb, udev, pipe, NULL, buf->len, complete_fn,
> > +			  context);
> > +
> > +	if (udev->bus->sg_tablesize > 0) {
> > +		buf->urb->num_sgs = buf->num_sgs;
> > +	} else {
> > +		WARN_ON_ONCE(buf->num_sgs != 1);
> > +		/* See usb_sg_init() */
> > +		buf->urb->num_sgs = 0;
> > +		if (!PageHighMem(sg_page(buf->urb->sg)))
> > +			buf->urb->transfer_buffer = sg_virt(buf->urb->sg);
> 
> please correct me if I am wrong but doing so we will use transfer_buffer
> for 95% of the use cases, right? If so why not keep it simple and always
> use it when sg_tablesize is 0 (avoiding SG I/O)?
>
> Btw this is what I proposed with the RFC series actually :) (always use
> transfer_buffer in the usb 2.0 case)

Because this way we do not change allocation method (use SG allocation)
what is simpler IMHO than having two buffer allocation methods.

And this way we do not hide problems with SG allocation and test it.

Additionally this patch address actual bug: using wrong urb->num_sgs and
can be easier to backport to older releases than 4 patch series. 

Stanislaw

  reply	other threads:[~2019-02-12 13:15 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 [this message]
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
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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20190212131542.GC12906@redhat.com \
    --to=sgruszka@redhat.com \
    --cc=dianders@chromium.org \
    --cc=hminas@synopsys.com \
    --cc=linux-usb@vger.kernel.org \
    --cc=linux-wireless@vger.kernel.org \
    --cc=lorenzo.bianconi@redhat.com \
    --cc=nbd@nbd.name \
    --cc=stefan.wahren@i2se.com \
    --cc=stern@rowland.harvard.edu \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).