[PATCH linux dev-4.10] aspeed_g5_defconfig: add CONFIG_OF_DYNAMIC.

[Mykola Kostenok]

> -----Original Message-----
> From: joel.stan at gmail.com [mailto:joel.stan at gmail.com] On Behalf Of Joel
> Stanley
> Sent: Tuesday, August 8, 2017 4:09 PM
> To: Mykola Kostenok <c_mykolak at mellanox.com>
> Cc: OpenBMC Maillist <openbmc at lists.ozlabs.org>; Vadim Pasternak
> <vadimp at mellanox.com>; Ohad Oz <ohado at mellanox.com>; Benjamin
> Herrenschmidt <benh at kernel.crashing.org>; Michael Ellerman
> <mpe at ellerman.id.au>; Jeremy Kerr <jk at ozlabs.org>
> Subject: Re: [PATCH linux dev-4.10] aspeed_g5_defconfig: add
> CONFIG_OF_DYNAMIC.
> 
> Hey Mykola,
> 
> On Fri, Aug 4, 2017 at 12:48 AM, Mykola Kostenok
> <c_mykolak at mellanox.com> wrote:
> > Add CONFIG_OF_DYNAMIC for hotplug operations.
> > It requires CONFIG_OF_UNITTEST so it added too.
> >
> > Signed-off-by: Mykola Kostenok <c_mykolak at mellanox.com>
> > ---
> >  arch/arm/configs/aspeed_g5_defconfig | 2 ++
> >  1 file changed, 2 insertions(+)
> >
> > diff --git a/arch/arm/configs/aspeed_g5_defconfig
> > b/arch/arm/configs/aspeed_g5_defconfig
> > index 2025e45..e78e306 100644
> > --- a/arch/arm/configs/aspeed_g5_defconfig
> > +++ b/arch/arm/configs/aspeed_g5_defconfig
> > @@ -215,3 +215,5 @@ CONFIG_DEBUG_USER=y  #
> CONFIG_XZ_DEC_POWERPC is
> > not set  # CONFIG_XZ_DEC_IA64 is not set  # CONFIG_XZ_DEC_SPARC is
> not
> > set
> > +CONFIG_OF_UNITTEST=y
> > +CONFIG_OF_DYNAMIC=y
> 
> I'm not sure that this is something we want enabled:
> 
> CONFIG_OF_UNITTEST:
>  This option builds in test cases for the device tree infrastructure  that are
> executed once at boot time, and the results dumped to the  console.
> 
> CONFIG_OF_DYNAMIC:
>  On some platforms, the device tree can be manipulated at runtime.
>  While this option is selected automatically on such platforms, you  can
> enable it manually to improve device tree unit test coverage.
> 
> Can you explain what you're wanting to do here?
> 
> I've added some of our device tree experts to cc so they can offer advice.
> 
> Cheers,
> 
> Joel

Hi, Joel.

We have now patchset supporting our CPLD device in upstream review.
There we have support for dynamic (hotplug) devices, like PSUs, FANs, ASIC, etc.  

These devices are described in DTS like, f.e. 
&i2c3 {
	status = "okay";
	#address-cells = <1>;
	#size-cells = <0>;

	psu1_eeprom: eeprom at 51 {
		compatible = "atmel,24c02";
		reg = <0x51>;
		status = "disabled";
	};

	psu2_eeprom: eeprom at 50 {
		compatible = "atmel,24c02";
		reg = <0x50>;
		status = "disabled";
	};

	psu1_ctrl: dps460 at 59 {
		compatible = "dps460";
		reg = <0x59>;
		status = "disabled";
	};

	psu2_ctrl: dps460 at 58 {
		compatible = "dps460";
		reg = <0x58>;
		status = "disabled";
	};
};

&i2c12 {
	status = "okay";
	#address-cells = <1>;
	#size-cells = <0>;

	asic_thermal: mlxsw_minimal at 48 {
		compatible = "mlxsw_minimal";
		reg = <0x48>;
		status = "disabled";
		cooling-phandle = <&cooling>;

		trips {
			/* trip type, temp in mcelsius, temp min, temp max */
			trip at 0 {
				trip = <0 75000 0 0>;
			};
			trip at 1 {
				trip = <2 85000 1 5>;
			};
			trip at 3 {
				trip = <2 105000 5 5>;
			};
		};
	};
};

They all sets with the state "disabled", and driver activates it with the below calls, when related hotplug event is received in interrupt handler:

static struct property mlxreg_core_device_dis = {
	.name = MLXREG_CORE_PROP_STATUS,
	.value = MLXREG_CORE_PROP_DISABLED,
	.length = sizeof(MLXREG_CORE_PROP_DISABLED),
};

static void mlxreg_core_dev_enable(struct device_node *np) {
	/* Enable and create device. */
	of_update_property(np, &mlxreg_core_device_en); }

static void mlxreg_core_dev_disable(struct device_node *np) {
	/* Disable and unregister platform device. */
	of_update_property(np, &mlxreg_core_device_dis);
	of_node_clear_flag(np, OF_POPULATED);
}

For that we must have OF_DYNAMIC set, and last one required OF_UNITEST.

Best regards. Mykola Kostenok.