Messages in this thread | | | Date | Thu, 17 Jan 2019 22:38:29 +0530 | From | Manivannan Sadhasivam <> | Subject | Re: [PATCH 2/8 v4] Documentation: bindings: dma: Add binding for dma-channel-mask |
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On Wed, Jan 16, 2019 at 09:10:23AM -0800, John Stultz 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. > > This follows the pre-existing bcm,dma-channel-mask binding. > > 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 > v4: Reworked to generic dma-channel-mask > --- > Documentation/devicetree/bindings/dma/dma.txt | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/Documentation/devicetree/bindings/dma/dma.txt b/Documentation/devicetree/bindings/dma/dma.txt > index 6312fb0..eeb4e4d 100644 > --- a/Documentation/devicetree/bindings/dma/dma.txt > +++ b/Documentation/devicetree/bindings/dma/dma.txt > @@ -16,6 +16,9 @@ Optional properties: > - dma-channels: Number of DMA channels supported by the controller. > - dma-requests: Number of DMA request signals supported by the > controller. > +- dma-channel-mask: Bitmask of available DMA channels in ascending order > + that are not reserved by firmware and are available to > + the kernel. i.e. first channel corresponds to LSB.
A general assumption is, "dma-channel-mask" refers to the bit fields of the channels which needs to be masked. But here, it refers to the channels which are available. Doesn't it contradict?
Thanks, Mani
> > Example: > > @@ -29,6 +32,7 @@ Example: > #dma-cells = <1>; > dma-channels = <32>; > dma-requests = <127>; > + dma-channel-mask = <0xfffe> > }; > > * DMA router > -- > 2.7.4 >
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