linux-kernel - Re: [PATCH v2 7/9] ARM: STi: DT: STiH407: Add FDMA driver dt nodes.

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Message-ID: <20150911193345.GR18779@x1>
Date:	Fri, 11 Sep 2015 20:33:45 +0100
From:	Lee Jones <lee.jones@...aro.org>
To:	Peter Griffin <peter.griffin@...aro.org>
Cc:	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	srinivas.kandagatla@...il.com, maxime.coquelin@...com,
	patrice.chotard@...com, vinod.koul@...el.com, robh+dt@...nel.org,
	dmaengine@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH v2 7/9] ARM: STi: DT: STiH407: Add FDMA driver dt nodes.

On Fri, 11 Sep 2015, Peter Griffin wrote:
> On Fri, 11 Sep 2015, Lee Jones wrote:
> > On Fri, 11 Sep 2015, Peter Griffin wrote:
> > > On Fri, 11 Sep 2015, Lee Jones wrote:
> > > > On Fri, 11 Sep 2015, Peter Griffin wrote:
> > > > 
> > > > > These nodes are required to get the fdma driver working
> > > > > on STiH407 based silicon.
> > > > > 
> > > > > Signed-off-by: Peter Griffin <peter.griffin@...aro.org>
> > > > > ---
> > > > >  arch/arm/boot/dts/stih407-family.dtsi | 51 +++++++++++++++++++++++++++++++++++
> > > > >  1 file changed, 51 insertions(+)
> > > > > 
> > > > > diff --git a/arch/arm/boot/dts/stih407-family.dtsi b/arch/arm/boot/dts/stih407-family.dtsi
> > > > > index 838b812..da07474b 100644
> > > > > --- a/arch/arm/boot/dts/stih407-family.dtsi
> > > > > +++ b/arch/arm/boot/dts/stih407-family.dtsi
> > > > > @@ -565,5 +565,56 @@
> > > > >  						  <&phy_port2 PHY_TYPE_USB3>;
> > > > >  			};
> > > > >  		};
> > > > > +
> > > > > +		fdma0: fdma0-audio@...0000 {
> > > > 
> > > > I'm not familiar with the FDMA driver, so can't comment knowledgeably,
> > > > but the <dev> part of <dev>@<base_address> should only describe the
> > > > type of hardware.  I believe in this case it should just be
> > > > dma@...20000.  Also notice the leading zero in the address, which I
> > > > believe mitigates possible confusion.  Then you be more specific with
> > > > the label, so something like 'fdma-audio' seems appropriate here.
> > > 
> > > Ok, can change to that format in v3.
> > > 
> > > > 
> > > > > +			compatible = "st,stih407-fdma-mpe31";
> > > > > +			reg = <0x8e20000 0x20000>;
> > > > 
> > > > I personally find padding up to 32bits helpful in the addresses.
> > > 
> > > None of the stih407-family nodes I can see have this padding, including
> > > the ones merged by you.
> > 
> > Nither of these two facts mean it's correct.
> 
> I thought it was a 'personal' thing. If it is mandated by the spec, then that
> is different.
> 
> > 
> > I'm happy to write a patch to correct them all.
> 
> Are you sure your actually correcting anything? Where does it say you
> should have a leading zero?
> 
> > 
> > Bear in mind that this isn't a hard and fast rule.  Both work and are
> > legal.  I just think the padding is more consistent.
> 
> Surely adding a patch with how the nodes are currently formatted, is more consistent
> than adding a patch with padding?
 
I did mean consistent with the majority of DTS files, rather than just
ours.  There are examples of non-padded values and it's perfectly
legal, but the vast majority of examples do in fact pad their
addresses [see below].  The change is more of a nit than a blocker.

git grep '@0[0-9|a-f]\{7\}' -- arch/arm/boot/dts/
892

git grep '@[0-9|a-f]\{7\} ' -- arch/arm/boot/dts/ | grep -vi sti | \
  grep -vi partition | grep -vi data
140

I'll probably still fix them up and resubmit some patches to bring us
into line with the vast majority.

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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