From: Vinod Koul <vkoul@kernel.org>
To: John Stultz <john.stultz@linaro.org>
Cc: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>,
lkml <linux-kernel@vger.kernel.org>,
Rob Herring <robh+dt@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Tanglei Han <hantanglei@huawei.com>,
Zhuangluan Su <suzhuangluan@hisilicon.com>,
Ryan Grachek <ryan@edited.us>,
"open list:DMA GENERIC OFFLOAD ENGINE SUBSYSTEM"
<dmaengine@vger.kernel.org>,
"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
<devicetree@vger.kernel.org>
Subject: Re: [PATCH 2/8 v4] Documentation: bindings: dma: Add binding for dma-channel-mask
Date: Sun, 20 Jan 2019 16:36:42 +0530 [thread overview]
Message-ID: <20190120110642.GT4635@vkoul-mobl> (raw)
In-Reply-To: <CALAqxLXc4dE=65MYR5M_jA-uKeGjsN0CL+JjDYbZUTyi+mKUTA@mail.gmail.com>
On 17-01-19, 09:43, John Stultz wrote:
> On Thu, Jan 17, 2019 at 9:08 AM Manivannan Sadhasivam
> <manivannan.sadhasivam@linaro.org> wrote:
> >
> > 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?
>
> Hrm. So while I can sort of understand the common usage of "mask" as
> to "hide", thus the desire to have a bitfield mean "the channels we
> hide" or "don't use", but in my experience bitmasking is more commonly
> used to keep only a portion of the the bits, so from that perspective
> its more intuitive that a mask be the channels we keep to use. So I'm
> not sure if your suggestion makes it more clear.
>
> But I'm not very particular here, so I'll defer to others on this.
Given the context and documentation which explicitly says it is bitmask
of available channels, i think we are fine :)
--
~Vinod
next prev parent reply other threads:[~2019-01-20 11:08 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-16 17:10 [PATCH 0/8 v4] k3dma patches to add support for hi3660/HiKey960 John Stultz
2019-01-16 17:10 ` [PATCH 1/8 v4] Documentation: bindings: k3dma: Extend the k3dma driver binding to support hisi-asp John Stultz
2019-01-16 17:10 ` [PATCH 2/8 v4] Documentation: bindings: dma: Add binding for dma-channel-mask John Stultz
2019-01-17 17:08 ` Manivannan Sadhasivam
2019-01-17 17:43 ` John Stultz
2019-01-20 11:06 ` Vinod Koul [this message]
2019-01-22 1:13 ` Rob Herring
2019-01-16 17:10 ` [PATCH 3/8 v4] dma: k3dma: Upgrade k3dma driver to support hisi_asp_dma hardware John Stultz
2019-01-20 11:11 ` Vinod Koul
2019-01-22 23:48 ` John Stultz
2019-01-23 12:55 ` Vinod Koul
2019-01-24 4:32 ` John Stultz
2019-01-16 17:10 ` [PATCH 4/8 v4] dma: k3dma: Delete axi_config John Stultz
2019-01-16 17:10 ` [PATCH 5/8 v4] dma: k3dma: Add support for dma-channel-mask John Stultz
2019-01-17 17:14 ` Manivannan Sadhasivam
2019-01-23 0:27 ` John Stultz
2019-01-16 17:10 ` [PATCH 6/8 v4] arm64: dts: hi3660: Add dma to uart nodes John Stultz
2019-01-16 17:10 ` [PATCH 7/8 v4] arm64: dts: hi3660: Add hisi asp dma device John Stultz
2019-01-16 17:10 ` [PATCH 8/8 v4] arm64: dts: hi3660: Fixup unofficial dma-min-chan to dma-channel-mask John Stultz
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