Hi Lucas,

On Thu, Mar 23, 2017 at 03:35:49PM +0100, Lucas Stach wrote:

Hi Dong,

Am Freitag, den 24.03.2017, 14:24 +0800 schrieb Dong Aisheng:
[...]

quoted

quoted

+static struct platform_driver imx7_pgc_domain_driver = {
+	.driver = {
+		.name = "imx7-pgc",
+	},
+	.probe    = imx7_pgc_domain_probe,
+	.remove   = imx7_pgc_domain_remove,
+	.id_table = imx7_pgc_domain_id,
+};
+builtin_platform_driver(imx7_pgc_domain_driver)

Again, i have a fundamental question about this patch implementation
that why we choose above way to register the power domain?

I'm sorry that i did not know too much history.
Would you guys please help share some information?

Because AFAIK this way will register each domain as a power domain
provider which is a bit violate the real HW and current power domain
framework design. And it is a bit more complicated to use than before.

IMHO i would rather prefer the old traditional and simpler way that one
provider (GPC) supplies multiple domains (PCIE/MIPI/HSIC PHY domain)
than this patch does.

However, i might be wrong. Please help to clear.

This way we can properly describe each power domain with the regulator
supplying the domain and the clocks of the devices inside the domain in
the device tree.

Thanks for the explaination. I understand that purpose.

Now my concern is why we doing things like this:
Builtin two platforms driver and use one to dynamically create
device to trigger another driver bind to register the domain.

static int imx7_pgc_domain_probe(struct platform_device *pdev)
{
        of_genpd_add_provider_simple(domain->dev->of_node,
                                           &domain->genpd);
}

static struct platform_driver imx7_pgc_domain_driver = {
        .driver = {
                .name = "imx7-pgc",
        },
        .probe    = imx7_pgc_domain_probe,
};
builtin_platform_driver(imx7_pgc_domain_driver)


static int imx_gpcv2_probe(struct platform_device *pdev)
{

        for_each_child_of_node(pgc_np, np) {
                pd_pdev = platform_device_alloc("imx7-pgc-domain",
                                                domain_index);
                ret = platform_device_add(pd_pdev);
	}
}

static struct platform_driver imx_gpc_driver = {
        .driver = {
                .name = "imx-gpcv2",
                .of_match_table = imx_gpcv2_dt_ids,
        }, 
        .probe = imx_gpcv2_probe,
};
builtin_platform_driver(imx_gpc_driver)

Is there any special purpose or i missed something?

Can we just use one or a simple core_initcall(imx_gpcv2_probe) cause
this probably should be registered early for other consumers?

Personally i'd be more like Rockchip's power domain implementation.
See:
arch/arm/boot/dts/rk3288.dtsi
drivers/soc/rockchip/pm_domains.c
Dcumentation/devicetree/bindings/soc/rockchip/power_domain.txt

How about refer to the Rockchip's way?

Then it could also address our issues and the binding would be
still like:
gpc: gpc at 303a0000 {
        compatible = "fsl,imx7d-gpc";
        reg = <0x303a0000 0x1000>;
        interrupt-controller;
        interrupts = <GIC_SPI 87 IRQ_TYPE_LEVEL_HIGH>;
        #interrupt-cells = <3>;
        interrupt-parent = <&intc>;

        pgc {
                #address-cells = <1>;
                #size-cells = <0>;

                pgc_pcie_phy: power-domain at IMX7_POWER_DOMAIN_PCIE_PHY {
                        reg = <IMX7_POWER_DOMAIN_PCIE_PHY>;
                        power-supply = <&reg_1p0d>;
			clocks = <xxx>;
                };

		....
        };
};

It also drops #power-domain-cells and register domain by
one provider with multi domains which is more align with HW.

How do you think of it?

Regards
Dong Aisheng

This is needed as for the upstream version we are controlling the
regulator from the GPC driver, as opposed to the downstream version,
where each device has to implement the regulator handling and power
up/down sequencing.

See the rationale in the commits adding the multidomain support to the
i.MX6 GPC.

Regards,
Lucas