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From:   Rob Herring <robh+dt@kernel.org>
Date:   Fri, 11 Jan 2019 14:04:30 -0600
Message-ID: <CAL_JsqJLm_tDakS10gch8K_3F+mHrzR3isw8Tm=D-R118D1sYQ@mail.gmail.com>
Subject: Re: [PATCH 2/8 v3] Documentation: bindings: k3dma: Add binding for hisi-dma-avail-chan
To:     John Stultz <john.stultz@linaro.org>
Cc:     lkml <linux-kernel@vger.kernel.org>, Vinod Koul <vkoul@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Tanglei Han <hantanglei@huawei.com>,
        Zhuangluan Su <suzhuangluan@hisilicon.com>,
        Ryan Grachek <ryan@edited.us>,
        Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>,
        "open list:DMA GENERIC OFFLOAD ENGINE SUBSYSTEM" 
        <dmaengine@vger.kernel.org>, devicetree@vger.kernel.org
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On Fri, Jan 11, 2019 at 1:58 PM Rob Herring <robh+dt@kernel.org> wrote:
>
> On Thu, Jan 10, 2019 at 11:34 AM John Stultz <john.stultz@linaro.org> wrote:
> >
> > Some dma channels can be reserved for secure mode or other
> > hardware on the SoC, so provide a binding for a bitmask
> > listing the available channels for the kernel to use.
> >
> > Cc: Vinod Koul <vkoul@kernel.org>
> > Cc: Rob Herring <robh+dt@kernel.org>
> > Cc: Mark Rutland <mark.rutland@arm.com>
> > Cc: Tanglei Han <hantanglei@huawei.com>
> > Cc: Zhuangluan Su <suzhuangluan@hisilicon.com>
> > Cc: Ryan Grachek <ryan@edited.us>
> > Cc: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> > Cc: dmaengine@vger.kernel.org
> > Cc: devicetree@vger.kernel.org
> > Signed-off-by: John Stultz <john.stultz@linaro.org>
> > ---
> > v3: Renamed to hisi-dma-avail-chan
> > ---
> >  Documentation/devicetree/bindings/dma/k3dma.txt | 3 +++
> >  1 file changed, 3 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/dma/k3dma.txt b/Documentation/devicetree/bindings/dma/k3dma.txt
> > index 10a2f15..38825d4 100644
> > --- a/Documentation/devicetree/bindings/dma/k3dma.txt
> > +++ b/Documentation/devicetree/bindings/dma/k3dma.txt
> > @@ -14,6 +14,9 @@ Required properties:
> >                 have specific request line
> >  - clocks: clock required
> >
> > +Optional properties:
> > +- hisi-dma-avail-chan: Bitmask of available physical channels
>
> Not quite right. Should be: hisilicon,dma-avail-chan

Actually, we already have the same case elsewhere with
'brcm,dma-channel-mask'. Maybe there are others. So make the property
common (i.e. documented in dma.txt) and called 'dma-channel-mask'.

Whether or not the dmaengine handles this or not is irrelevant to
whether the binding is common or not. I have no say over OS design
decisions.

Rob