linux-kernel - Re: [PATCH v7 08/10] arm64: dts: HiSilicon: Add support for HiKey 970 PCIe controller hardware

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Message-ID: <20210724041150.GA4053@thinkpad>
Date:   Sat, 24 Jul 2021 09:41:50 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
Cc:     Vinod Koul <vkoul@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.com>,
        Rob Herring <robh@...nel.org>, linuxarm@...wei.com,
        mauro.chehab@...wei.com,
        Krzysztof Wilczyński <kw@...ux.com>,
        Binghui Wang <wangbinghui@...ilicon.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Rob Herring <robh+dt@...nel.org>,
        Wei Xu <xuwei5@...ilicon.com>,
        Xiaowei Song <songxiaowei@...ilicon.com>,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org
Subject: Re: [PATCH v7 08/10] arm64: dts: HiSilicon: Add support for HiKey
 970 PCIe controller hardware

On Fri, Jul 23, 2021 at 08:53:18AM +0200, Mauro Carvalho Chehab wrote:
> Em Thu, 22 Jul 2021 19:06:28 +0530
> Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org> escreveu:
> 
> > On Wed, Jul 21, 2021 at 10:39:10AM +0200, Mauro Carvalho Chehab wrote:
> > > From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> > > 
> > > Add DTS bindings for the HiKey 970 board's PCIe hardware.
> > > 
> > > Co-developed-by: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
> > > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> > > Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
> > > ---
> > >  arch/arm64/boot/dts/hisilicon/hi3670.dtsi     | 71 +++++++++++++++++++
> > >  .../boot/dts/hisilicon/hikey970-pmic.dtsi     |  1 -
> > >  drivers/pci/controller/dwc/pcie-kirin.c       | 12 ----
> > >  3 files changed, 71 insertions(+), 13 deletions(-)
> > > 
> > > diff --git a/arch/arm64/boot/dts/hisilicon/hi3670.dtsi b/arch/arm64/boot/dts/hisilicon/hi3670.dtsi
> > > index 1f228612192c..6dfcfcfeedae 100644
> > > --- a/arch/arm64/boot/dts/hisilicon/hi3670.dtsi
> > > +++ b/arch/arm64/boot/dts/hisilicon/hi3670.dtsi
> > > @@ -177,6 +177,12 @@ sctrl: sctrl@...0a000 {
> > >  			#clock-cells = <1>;
> > >  		};
> > >  
> > > +		pmctrl: pmctrl@...31000 {
> > > +			compatible = "hisilicon,hi3670-pmctrl", "syscon";
> > > +			reg = <0x0 0xfff31000 0x0 0x1000>;
> > > +			#clock-cells = <1>;
> > > +		};
> > > +  
> > 
> > Irrelevant change to this patch.
> 
> Huh?
> 
> This is used by PCIe PHY, as part of the power on procedures:
> 
> 	+static int hi3670_pcie_noc_power(struct hi3670_pcie_phy *phy, bool enable)
> 	+{
> 	+       struct device *dev = phy->dev;
> 	+       u32 time = 100;
> 	+       unsigned int val = NOC_PW_MASK;
> 	+       int rst;
> 	+
> 	+       if (enable)
> 	+               val = NOC_PW_MASK | NOC_PW_SET_BIT;
> 	+       else
> 	+               val = NOC_PW_MASK;
> 	+       rst = enable ? 1 : 0;
> 	+
> 	+       regmap_write(phy->pmctrl, NOC_POWER_IDLEREQ_1, val);
> 
> 

Ah... you're hardcoding the syscon compatible in driver. Sorry missed that.

But if these syscon nodes are independent memory regions or belong to non
PCI/PHY memory map, you could've fetched the reference through a DT property
along with the offset then used it in driver.

Like,

	pcie_phy: pcie-phy@...00000 {
		...
		hisilicon,noc-power-regs = <&pmctrl 0x38c>;
		hisilicon,sctrl-cmos-regs = <&sctrl 0x60>;
		...
	};

The benefit of doing this way is, if the pmctrl, sctrl register layout changes
in future, you can handle it without any issues.

> 
> > 
> > >  		iomcu: iomcu@...7e000 {
> > >  			compatible = "hisilicon,hi3670-iomcu", "syscon";
> > >  			reg = <0x0 0xffd7e000 0x0 0x1000>;
> > > @@ -660,6 +666,71 @@ gpio28: gpio@...1d000 {
> > >  			clock-names = "apb_pclk";
> > >  		};
> > >    
> > 
> > [...]
> > 
> > > +			#interrupt-cells = <1>;
> > > +			interrupts = <0 283 4>;  
> > 
> > Use the DT flag for interrupts instead of hardcoded value
> 
> Do you mean like this?
> 
> 	interrupts = <0 283 IRQ_TYPE_LEVEL_HIGH>;
> 

yes but you could also use,

	interrupts = <GIC_SPI 283 IRQ_TYPE_LEVEL_HIGH>;

Thanks,
Mani