Re: [PATCH] host1x: cdma: use completion instead of semaphore

From: Thierry Reding <thierry.reding@gmail.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: emil.fsw@goode.io, Mikko Perttunen <cyndis@kapsi.fi>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	dri-devel <dri-devel@lists.freedesktop.org>,
	"open list:TEGRA ARCHITECTURE SUPPORT"
	<linux-tegra@vger.kernel.org>, Dmitry Osipenko <digetx@gmail.com>
Subject: Re: [PATCH] host1x: cdma: use completion instead of semaphore
Date: Tue, 11 Dec 2018 11:27:10 +0100	[thread overview]
Message-ID: <20181211102710.GH14426@ulmo> (raw)
In-Reply-To: <CAK8P3a08VEReXUZ39f3iQS3wUZSwKYObnn-jQrUiMJ4Gyx6hVQ@mail.gmail.com>

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On Tue, Dec 11, 2018 at 11:11:38AM +0100, Arnd Bergmann wrote:
> On Tue, Dec 11, 2018 at 11:08 AM Thierry Reding
> <thierry.reding@gmail.com> wrote:
> >
> > On Mon, Dec 10, 2018 at 10:51:04PM +0100, Arnd Bergmann wrote:
> > > In this usage, the two are completely equivalent, but the
> > > completion documents better what is going on, and we generally
> > > try to avoid semaphores these days.
> > >
> > > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> > > ---
> > >  drivers/gpu/host1x/cdma.c | 6 +++---
> > >  drivers/gpu/host1x/cdma.h | 4 ++--
> > >  2 files changed, 5 insertions(+), 5 deletions(-)
> >
> > My understanding is that potentially many userspace processes could be
> > blocking on this, which I think is the reason for it being a semaphore.
> > Is the completion going to work for those cases as well?
> 
> Yes, it behaves the exact same way here.

Great, I'll queue this for v4.22.

Thanks,
Thierry

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