linux-kernel - Re: [PATCH 6/8 v2] arm64: dts: hi3660: Add dma to uart nodes

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Date:   Fri, 4 Jan 2019 21:37:23 -0800
From:   John Stultz <john.stultz@...aro.org>
To:     Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Cc:     lkml <linux-kernel@...r.kernel.org>,
        Tanglei Han <hantanglei@...wei.com>,
        Zhuangluan Su <suzhuangluan@...ilicon.com>,
        Ryan Grachek <ryan@...ted.us>, Wei Xu <xuwei5@...ilicon.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>
Subject: Re: [PATCH 6/8 v2] arm64: dts: hi3660: Add dma to uart nodes

On Fri, Jan 4, 2019 at 8:34 PM John Stultz <john.stultz@...aro.org> wrote:
>
> On Fri, Jan 4, 2019 at 7:49 PM Manivannan Sadhasivam
> <manivannan.sadhasivam@...aro.org> wrote:
> >
> > Hi John,
> >
> > On Fri, Jan 04, 2019 at 12:56:26PM -0800, John Stultz wrote:
> > > Try to add DMA support to the uart nodes following
> > > the assignments made in the dts from the victoria vendor kernel
> > > here:
> > > https://consumer.huawei.com/en/opensource/detail/?siteCode=worldwide&keywords=p10&fileType=openSourceSoftware&pageSize=10&curPage=1
> > >
> > > Cc: Tanglei Han <hantanglei@...wei.com>
> > > Cc: Zhuangluan Su <suzhuangluan@...ilicon.com>
> > > Cc: Ryan Grachek <ryan@...ted.us>
> > > Cc: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> > > Cc: Wei Xu <xuwei5@...ilicon.com>
> > > Cc: Rob Herring <robh+dt@...nel.org>
> > > Cc: Mark Rutland <mark.rutland@....com>
> > > Cc: linux-arm-kernel@...ts.infradead.org
> > > Cc: devicetree@...r.kernel.org
> > > Signed-off-by: John Stultz <john.stultz@...aro.org>
> > > ---
> > >  arch/arm64/boot/dts/hisilicon/hi3660.dtsi | 10 ++++++++++
> > >  1 file changed, 10 insertions(+)
> > >
> > > diff --git a/arch/arm64/boot/dts/hisilicon/hi3660.dtsi b/arch/arm64/boot/dts/hisilicon/hi3660.dtsi
> > > index 20ae40d..aaa2b04 100644
> > > --- a/arch/arm64/boot/dts/hisilicon/hi3660.dtsi
> > > +++ b/arch/arm64/boot/dts/hisilicon/hi3660.dtsi
> > > @@ -466,6 +466,8 @@
> > >                       compatible = "arm,pl011", "arm,primecell";
> > >                       reg = <0x0 0xfdf02000 0x0 0x1000>;
> > >                       interrupts = <GIC_SPI 74 IRQ_TYPE_LEVEL_HIGH>;
> > > +                     dma-names = "rx", "tx";
> > > +                     dmas =  <&dma0 0 &dma0 1>;
> >
> > Usage of DMA channel 0 contradicts with the description provided in
> > patch, "dma: k3dma: Add support to dma_avail_chan".
>
> Hrm. Good point.  I'll double check w/ Dr Su on this, I'm not sure if
> that inconsistency is due to the the vendor kernel (where these came
> from) having different reserved channels or just something overlooked
> if the uart0 is not actually being used (as we find on hikey960 as
> well).

Hrm. So it seems like uart0 is mapped to the dma0 chan0, but the
device specific files in the vendor tree overwite the dma values:
                serial0: uart@...02000 {
                        pinctrl-names = "default", "idle";
                        pinctrl-0 = <&gpio053_pmx_func
&gpio054_pmx_func &gpio053_cfg_func &gpio054_cfg_func>;
                        pinctrl-1 = <&gpio053_pmx_idle
&gpio054_pmx_idle &gpio053_cfg_idle &gpio054_cfg_idle>;
                        dma-names = "", "";
                        dmas = <>;
                        clock-rate = <0 19200000>;
                        status = "ok";
                };

But I went ahead and pulled the dma values on uart0.

thaks
-john