From: Mark Rutland <mark.rutland@arm.com>
To: Rob Herring <robherring2@gmail.com>
Cc: Suman Anna <s-anna@ti.com>, Ohad Ben-Cohen <ohad@wizery.com>,
Kumar Gala <galak@codeaurora.org>,
Bjorn Andersson <bjorn@kryo.se>,
Josh Cartwright <joshc@codeaurora.org>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-omap@vger.kernel.org" <linux-omap@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
Rob Herring <robh+dt@kernel.org>
Subject: Re: [PATCH v7 1/4] Documentation: dt: add common bindings for hwspinlock
Date: Fri, 16 Jan 2015 10:19:03 +0000 [thread overview]
Message-ID: <20150116101903.GB21809@leverpostej> (raw)
In-Reply-To: <CAL_JsqL2LZAooMk-V8+xeF2g6acZE21M+-OBRw8aEVa-5wVHuQ@mail.gmail.com>
On Thu, Jan 15, 2015 at 02:42:23PM +0000, Rob Herring wrote:
> On Thu, Jan 15, 2015 at 7:55 AM, Mark Rutland <mark.rutland@arm.com> wrote:
> > On Thu, Jan 15, 2015 at 01:52:01PM +0000, Mark Rutland wrote:
> >> On Wed, Jan 14, 2015 at 08:58:18PM +0000, Suman Anna wrote:
> >> > This patch adds the generic common bindings used to represent
> >> > a hwlock device and use/request locks in a device-tree build.
> >> >
> >> > All the platform-specific hwlock driver implementations need the
> >> > number of locks and associated base id for registering the locks
> >> > present within the device with the driver core. This base id
> >> > needs to be unique across multiple IP instances of a hwspinlock
> >> > device, so that each hwlock can be represented uniquely in a
> >> > system.
> >> >
> >> > The number of locks is represented by 'hwlock-num-locks' property,
> >> > and the base id is represented by the 'hwlock-base-id' property.
> >> > The args specifier length is dependent on each vendor-specific
> >> > implementation and is represented through the '#hwlock-cells'
> >> > property. Client users need to use the property 'hwlocks' for
> >> > requesting specific lock(s).
> >> >
> >> > Note that the document is named hwlock.txt deliberately to keep
> >> > it a bit more generic.
> >> >
> >> > Cc: Rob Herring <robh+dt@kernel.org>
> >> > Signed-off-by: Suman Anna <s-anna@ti.com>
> >> > ---
> >> > v7: Revised binding info for hwlock-base-id, it is mandatory now
> >> >
> >> > .../devicetree/bindings/hwlock/hwlock.txt | 55 ++++++++++++++++++++++
> >> > 1 file changed, 55 insertions(+)
> >> > create mode 100644 Documentation/devicetree/bindings/hwlock/hwlock.txt
> >> >
> >> > diff --git a/Documentation/devicetree/bindings/hwlock/hwlock.txt b/Documentation/devicetree/bindings/hwlock/hwlock.txt
> >> > new file mode 100644
> >> > index 000000000000..8de7aaf878f9
> >> > --- /dev/null
> >> > +++ b/Documentation/devicetree/bindings/hwlock/hwlock.txt
> >> > @@ -0,0 +1,55 @@
> >> > +Generic hwlock bindings
> >> > +=======================
> >> > +
> >> > +Generic bindings that are common to all the hwlock platform specific driver
> >> > +implementations.
> >> > +
> >> > +The validity and need of these common properties may vary from one platform
> >> > +implementation to another. The platform specific bindings should explicitly
> >> > +state if an optional property is used. Please also look through the individual
> >> > +platform specific hwlock binding documentations for identifying the applicable
> >> > +properties.
> >> > +
> >> > +Common properties:
> >> > +- #hwlock-cells: Specifies the number of cells needed to represent a
> >> > + specific lock. This property is mandatory for all
> >> > + platform implementations.
> >> > +- hwlock-num-locks: Number of locks present in a hwlock device. This
> >> > + property is needed on hwlock devices, where the number
> >> > + of supported locks within a hwlock device cannot be
> >> > + read from a register.
> >> > +- hwlock-base-id: An unique base Id for the locks for a particular hwlock
> >> > + device. This property is mandatory for all platform
> >> > + implementations.
> >>
> >> This property makes no sense. The ID encoded in the hwlock cells is
> >> relative to the instance (identified by phandle), not global. So the DT
> >> has no global ID space.
> >>
> >> Why do you think you need this?
> >
> > Having looked at the way this proeprty is used, NAK.
> >
> > If you need to carve up a Linux-internal ID space, do that dynamically.
> > There is no need for this property.
>
> Better yet, don't create a Linux ID space for this. Everywhere we have
> one, we want to get rid of it.
Agreed. A completely opaque token / desc structure would prevent a lot
of potential abuse and save us from painful breakage.
Mark
next prev parent reply other threads:[~2015-01-16 10:19 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-14 20:58 [PATCH v7 0/4] hwspinlock core & omap dt support Suman Anna
2015-01-14 20:58 ` [PATCH v7 1/4] Documentation: dt: add common bindings for hwspinlock Suman Anna
2015-01-15 13:52 ` Mark Rutland
2015-01-15 13:55 ` Mark Rutland
2015-01-15 14:42 ` Rob Herring
2015-01-15 20:16 ` Suman Anna
2015-01-16 6:09 ` Ohad Ben-Cohen
2015-01-16 10:17 ` Mark Rutland
2015-01-17 0:46 ` Ohad Ben-Cohen
2015-01-20 18:05 ` Tony Lindgren
2015-01-21 12:41 ` Ohad Ben-Cohen
2015-01-21 17:56 ` Suman Anna
2015-01-22 18:56 ` Mark Rutland
2015-01-29 3:58 ` Suman Anna
2015-02-11 11:29 ` Mark Rutland
2015-02-16 18:06 ` Bjorn Andersson
2015-01-30 23:29 ` Bjorn Andersson
2015-01-31 5:41 ` Ohad Ben-Cohen
2015-02-01 11:00 ` Ohad Ben-Cohen
2015-02-02 21:14 ` Suman Anna
2015-02-01 17:55 ` Bjorn Andersson
2015-02-02 21:07 ` Suman Anna
2015-02-05 23:01 ` Bjorn Andersson
2015-02-06 0:11 ` Suman Anna
2015-02-06 0:34 ` Bjorn Andersson
2015-02-11 10:29 ` Ohad Ben-Cohen
2015-02-11 11:35 ` Mark Rutland
2015-02-16 20:30 ` Bjorn Andersson
2015-01-16 10:19 ` Mark Rutland [this message]
2015-01-16 17:49 ` Suman Anna
2015-01-14 20:58 ` [PATCH v7 2/4] Documentation: dt: add the omap hwspinlock bindings document Suman Anna
2015-01-14 20:58 ` [PATCH v7 3/4] hwspinlock/core: add common OF helpers Suman Anna
2015-01-14 20:58 ` [PATCH v7 4/4] hwspinlock/omap: add support for dt nodes Suman Anna
2015-01-15 10:13 ` [PATCH v7 0/4] hwspinlock core & omap dt support Ohad Ben-Cohen
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