LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: "Ahmed S. Darwish" <darwish.07@gmail.com>
To: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: bryan.wu@analog.com, Andrey Panin <pazke@donpac.ru>,
	Roel Kluin <12o3l@tiscali.nl>,
	linux-input@atrey.karlin.mff.cuni.cz,
	linux-joystick@atrey.karlin.mff.cuni.cz,
	linux-kernel@vger.kernel.org, akpm@linux-foundation.org,
	Jean Delvare <khali@linux-fr.org>
Subject: Re: [PATCH try #3] Input/Joystick Driver: add support AD7142 joystick driver
Date: Mon, 15 Oct 2007 20:27:43 +0200	[thread overview]
Message-ID: <20071015182743.GA2529@Ahmed> (raw)
In-Reply-To: <d120d5000710150848t1993b0aavbbc0cd7971e3ef3e@mail.gmail.com>

On Mon, Oct 15, 2007 at 11:48:17AM -0400, Dmitry Torokhov wrote:
> Hi Bryan,
> 
> On 10/15/07, Bryan Wu <bryan.wu@analog.com> wrote:
> > +
> > +static int ad7142_thread(void *nothing)
> > +{
> > +       do {
> > +               wait_for_completion(&ad7142_completion);
> > +               ad7142_decode();
> > +               enable_irq(CONFIG_BFIN_JOYSTICK_IRQ_PFX);
> > +       } while (!kthread_should_stop());
> > +
> 
> No, this is not going to work well:
> - you at least need to reinitialize the completion before enabling
> IRQ, otherwise you will spin in a very tight loop
> - if noone would touch the joystick ad7142_clsoe would() block
> infinitely because noone would signal the completion and
> ad7142_thread() would never stop.
> 
> Completion is just not a good abstraction here... Please use work
> abstraction and possibly a separate workqueue.
> 

Bryan, I'm very interested in the technical advantage of using a completion
here.

In my _not-experienced_ opinion, I remember completions was created mainly for
"create_task, wait till task got finished, go on" case. Why using it in a
different context while workqueues was created for a similar situation to
ad7142 one (non-irq context bottom-half) ?

Regards,

-- 
Ahmed S. Darwish
HomePage: http://darwish.07.googlepages.com
Blog: http://darwish-07.blogspot.com

  parent reply	other threads:[~2007-10-15 18:28 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-10-15 14:47 Bryan Wu
2007-10-15 15:48 ` Dmitry Torokhov
2007-10-15 17:24   ` Bryan Wu
2007-10-15 17:40     ` Dmitry Torokhov
2007-10-16  5:51       ` Bryan Wu
2007-10-16 16:53         ` Dmitry Torokhov
2007-10-15 18:27   ` Ahmed S. Darwish [this message]
2007-10-16  6:08     ` Bryan Wu
2007-10-16 16:40       ` Ahmed S. Darwish
2007-10-15 19:35   ` Jean Delvare

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=20071015182743.GA2529@Ahmed \
    --to=darwish.07@gmail.com \
    --cc=12o3l@tiscali.nl \
    --cc=akpm@linux-foundation.org \
    --cc=bryan.wu@analog.com \
    --cc=dmitry.torokhov@gmail.com \
    --cc=khali@linux-fr.org \
    --cc=linux-input@atrey.karlin.mff.cuni.cz \
    --cc=linux-joystick@atrey.karlin.mff.cuni.cz \
    --cc=linux-kernel@vger.kernel.org \
    --cc=pazke@donpac.ru \
    --subject='Re: [PATCH try #3] Input/Joystick Driver: add support AD7142 joystick driver' \
    /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

This is a public inbox, see mirroring instructions
on how to clone and mirror all data and code used for this inbox