From: Johan Hovold <johan@kernel.org>
To: Andreas Kemnade <andreas@kemnade.info>
Cc: Johan Hovold <johan@kernel.org>,
robh+dt@kernel.org, mark.rutland@arm.com,
devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
Discussions about the Letux Kernel
<letux-kernel@openphoenux.org>
Subject: Re: [PATCH v2 1/5] gnss: sirf: write data to gnss only when the gnss device is open
Date: Mon, 14 Jan 2019 13:00:21 +0100 [thread overview]
Message-ID: <20190114120021.GF3691@localhost> (raw)
In-Reply-To: <20190113215036.11c543db@aktux>
On Sun, Jan 13, 2019 at 09:50:36PM +0100, Andreas Kemnade wrote:
> On Thu, 10 Jan 2019 13:02:28 +0100
> Johan Hovold <johan@kernel.org> wrote:
>
> > On Sun, Dec 09, 2018 at 08:51:46PM +0100, Andreas Kemnade wrote:
> > > The api forbids writing data there otherwise. Prepare for the
> > > serdev_open()/close() being a part of runtime pm.
> > >
> > > Signed-off-by: Andreas Kemnade <andreas@kemnade.info>
> > > ---
> > > Changes in v2:
> > > add locking
> > >
> > > drivers/gnss/sirf.c | 28 +++++++++++++++++++++++++++-
> > > 1 file changed, 27 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/gnss/sirf.c b/drivers/gnss/sirf.c
> > > index 2c22836d3ffd..ba663de1db49 100644
> > > --- a/drivers/gnss/sirf.c
> > > +++ b/drivers/gnss/sirf.c
> > > @@ -35,6 +35,12 @@ struct sirf_data {
> > > struct gpio_desc *wakeup;
> > > int irq;
> > > bool active;
> > > + /*
> > > + * There might be races between returning data and closing the gnss
> > > + * device.
> > > + */
> >
> > Please drop this comment, which is too verbose. The mutex protects the
> > opened flag, and that could be indicated using a new line above the
> > mutex and below the flag, or using a short comment before the mutex.
> >
> > > + struct mutex gdev_mutex;
> >
> > Please rename "mutex". We should be able to reuse this for the serdev
> > open count as well, right?
>
> No. we cannot. The problem here is that we would take the same mutex
> in a serdev callback and around a serdev call. Then we have things like
> that:
>
> [ 36.700408] ======================================================
> [ 36.706970] WARNING: possible circular locking dependency detected
Right, we need to be able to flush as part of close. Thanks for
investigating, though.
Johan
next prev parent reply other threads:[~2019-01-14 12:00 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-09 19:51 [PATCH v2 0/5] gnss: sirf: add support for w2sg0004 + lna Andreas Kemnade
2018-12-09 19:51 ` [PATCH v2 1/5] gnss: sirf: write data to gnss only when the gnss device is open Andreas Kemnade
2019-01-10 12:02 ` Johan Hovold
2019-01-13 20:50 ` Andreas Kemnade
2019-01-14 12:00 ` Johan Hovold [this message]
2018-12-09 19:51 ` [PATCH v2 2/5] gnss: sirf: power on logic for devices without wakeup signal Andreas Kemnade
2019-01-10 12:10 ` Johan Hovold
2019-01-10 22:02 ` Andreas Kemnade
2019-01-14 10:51 ` Johan Hovold
2019-01-14 12:13 ` Andreas Kemnade
2019-01-22 8:38 ` Johan Hovold
2019-01-14 21:58 ` Andreas Kemnade
2019-01-15 9:08 ` Johan Hovold
2018-12-09 19:51 ` [PATCH v2 3/5] dt-bindings: gnss: add w2sg0004 compatible string Andreas Kemnade
2019-01-10 12:12 ` Johan Hovold
2018-12-09 19:51 ` [PATCH v2 4/5] gnss: sirf: add a separate supply for a lna Andreas Kemnade
2018-12-10 7:42 ` [Letux-kernel] " H. Nikolaus Schaller
2019-01-10 12:25 ` Johan Hovold
2018-12-09 19:51 ` [PATCH v2 5/5] dt-bindings: gnss: add lna-supply property Andreas Kemnade
2019-01-10 12:27 ` Johan Hovold
2019-01-10 17:07 ` Andreas Kemnade
2019-01-14 9:15 ` Johan Hovold
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