linux-kernel - RE: [PATCH v1] ARM: dts: aspeed: Adding Facebook Bletchley BMC

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Message-ID: <HKAPR04MB40039608E14195D859DE7EC5968D9@HKAPR04MB4003.apcprd04.prod.outlook.com>
Date:   Thu, 4 Nov 2021 03:30:08 +0000
From:   Howard Chiu (邱冠睿) <Howard.Chiu@...ntatw.com>
To:     Patrick Williams <patrick@...cx.xyz>,
        Howard Chiu <howard10703049@...il.com>
CC:     "arnd@...db.de" <arnd@...db.de>, "olof@...om.net" <olof@...om.net>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "joel@....id.au" <joel@....id.au>,
        "andrew@...id.au" <andrew@...id.au>,
        "soc@...nel.org" <soc@...nel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-aspeed@...ts.ozlabs.org" <linux-aspeed@...ts.ozlabs.org>
Subject: RE: [PATCH v1] ARM: dts: aspeed: Adding Facebook Bletchley BMC

Hi Patrick

> Hello Howard,
> 
> Thanks for supplying this.  I have a few comments below.
> 
> On Wed, Nov 03, 2021 at 03:14:18PM +0800, Howard Chiu wrote:
> > Initial introduction of Facebook Bletchley equipped with
> > Aspeed 2600 BMC SoC.
> >
> > Signed-off-by: Howard Chiu <howard.chiu@...ntatw.com>
> > ---
> >  arch/arm/boot/dts/Makefile                    |    1 +
> >  .../dts/aspeed-bmc-facebook-bletchley.dts     | 1160
> +++++++++++++++++
> >  2 files changed, 1161 insertions(+)
> >  create mode 100644
> arch/arm/boot/dts/aspeed-bmc-facebook-bletchley.dts
> >
> > diff --git a/arch/arm/boot/dts/Makefile b/arch/arm/boot/dts/Makefile
> > index 7e0934180724..2cc2d804e75a 100644
> > --- a/arch/arm/boot/dts/Makefile
> > +++ b/arch/arm/boot/dts/Makefile
> > @@ -1474,6 +1474,7 @@ dtb-$(CONFIG_ARCH_ASPEED) += \
> >  	aspeed-bmc-facebook-wedge400.dtb \
> >  	aspeed-bmc-facebook-yamp.dtb \
> >  	aspeed-bmc-facebook-yosemitev2.dtb \
> > +	aspeed-bmc-facebook-bletchley.dtb \
> >  	aspeed-bmc-ibm-everest.dtb \
> >  	aspeed-bmc-ibm-rainier.dtb \
> >  	aspeed-bmc-ibm-rainier-1s4u.dtb \
> 
> I believe the preference is to keep these sorted.
Will be fixed in the next patch
> 
> > diff --git a/arch/arm/boot/dts/aspeed-bmc-facebook-bletchley.dts
> b/arch/arm/boot/dts/aspeed-bmc-facebook-bletchley.dts
> > new file mode 100644
> > index 000000000000..af30be95fb23
> > --- /dev/null
> > +++ b/arch/arm/boot/dts/aspeed-bmc-facebook-bletchley.dts
> 
> > +
> > +	chosen {
> > +		bootargs = "console=ttyS4,115200n8";
> > +	};
> 
> Do we want this to be 115200 or 57600?
Will be modified to 57600 in the next patch
> 
> > +		fan1_ember {
> > +			retain-state-shutdown;
> > +			default-state = "off";
> > +			gpios = <&fan_ioexp 13 GPIO_ACTIVE_HIGH>;
> 
> I see a number of references to 'ember'/'EMBER'.  I think the intention is
> 'amber'.
> 
>     amber: a honey-yellow color typical of amber
>            or a yellow light used as a cautionary signal
> 
>     ember: a small piece of burning or glowing coal or wood in a dying fire.
Will be changed to "amber" in the next patch
> 
> 
> > +&fmc {
> > +	status = "okay";
> > +	flash@0 {
> > +		status = "okay";
> > +		m25p,fast-read;
> > +		label = "bmc";
> > +		spi-max-frequency = <50000000>;
> > +#include "openbmc-flash-layout-64.dtsi"
> 
> Is this board using 64MB or 128MB modules?  Many of the newer systems
> have been
> starting to use 128MB.  I just want to confirm this is correct.
1Gb SPI flash, MX66L1G45GMI-08G
> 
> > +	sled0_ioexp: pca9539@76 {
> > +		compatible = "nxp,pca9539";
> > +		reg = <0x76>;
> > +		#address-cells = <1>;
> > +		#size-cells = <0>;
> > +		gpio-controller;
> > +		#gpio-cells = <2>;
> > +
> > +		gpio-line-names =
> > +
> 	"","SLED0_BMC_CCG5_INT","SLED0_INA230_ALERT","SLED0_P12V_STBY_
> ALERT",
> > +
> 	"SLED0_SSD_ALERT","SLED0_MS_DETECT","SLED0_MD_REF_PWM","",
> > +
> 	"SLED0_MD_STBY_RESET","SLED0_MD_IOEXP_EN_FAULT","SLED0_MD_D
> IR","SLED0_MD_DECAY",
> > +
> 	"SLED0_MD_MODE1","SLED0_MD_MODE2","SLED0_MD_MODE3","SLED
> 0_AC_PWR_EN";
> 
> In general, in OpenBMC, we have a preference for the GPIOs to not be
> schematic
> names but to be named based on their [software-oriented] function.  Please
> take
> a look at:
> 
> 
> https://github.com/openbmc/docs/blob/master/designs/device-tree-gpio-na
> ming.md
> 
> Any function you see that isn't documented there we should try to get
> documented
> before fixing the GPIO name to match it.
> 
I intend to delete them for now if I have to document them first, because most of them are platform-specific GPIO, not for general purpose and also not suitable to current OpenBMC.
For example, OpenBMC believes there is only one GPIO to be used to power on the chassis, but Bletchley has six.
I define gpio-line-names for gpioset/geioget/phosphor-multi-gpio-monitor usage, and they can be replaced with gpiochip number and offset instead.
The disadvantage is that they won't be human-friendly when TEs develop their tool to test these GPIOs.
> > +		gpio-line-names =
> > +		"SLED0_EMBER_LED","SLED0_BLUE_LED","SLED0_RST_IOEXP","",
> 
> The LEDs are ones I know are already documented in the above linked file.
I can delete them because gpio-line-names is not necessary for usage.
They are added for human-friendly usage when using GPIO tools.
> 
> > +&i2c13 {
> > +	multi-master;
> > +	aspeed,hw-timeout-ms = <1000>;
> > +	status = "okay";
> > +};
> 
> Was this intentional to have defined a multi-master bus with nothing on it?
There is a OCP debug card which is a hot plugging device.
We only need to specify this bus with "multi-mater" property for IPMB support.
> 
> --
> Patrick Williams