linux-kernel - RE: [PATCH 1/2] ARM: imx: drop uneccessary of_platform_default

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Date:   Fri, 15 Mar 2019 10:16:53 +0000
From:   Aisheng Dong <aisheng.dong@....com>
To:     Peng Fan <peng.fan@....com>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>,
        "s.hauer@...gutronix.de" <s.hauer@...gutronix.de>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        "festevam@...il.com" <festevam@...il.com>,
        dl-linux-imx <linux-imx@....com>,
        Anson Huang <anson.huang@....com>,
        "arnd@...db.de" <arnd@...db.de>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     "van.freenix@...il.com" <van.freenix@...il.com>
Subject: RE: [PATCH 1/2] ARM: imx: drop uneccessary
 of_platform_default_populate

> From: Peng Fan
> 
> "arch_initcall_sync(of_platform_default_populate_init);" could be used to
> populate the device tree, there is no need to call of_platform_default_populate
> in machine code.
> 
> Tested on i.MX6Q-SDB i.MX6SL-EVK i.MX6UL-EVK board.
> 
> Signed-off-by: Peng Fan <peng.fan@....com>
> ---
>  arch/arm/mach-imx/mach-imx6q.c  | 2 --
>  arch/arm/mach-imx/mach-imx6sl.c | 2 --
>  arch/arm/mach-imx/mach-imx6sx.c | 2 --
>  arch/arm/mach-imx/mach-imx6ul.c | 1 -
>  4 files changed, 7 deletions(-)
> 
> diff --git a/arch/arm/mach-imx/mach-imx6q.c
> b/arch/arm/mach-imx/mach-imx6q.c index 7d80a0ae723c..655398c20256
> 100644
> --- a/arch/arm/mach-imx/mach-imx6q.c
> +++ b/arch/arm/mach-imx/mach-imx6q.c
> @@ -278,8 +278,6 @@ static void __init imx6q_init_machine(void)
> 
>  	imx6q_enet_phy_init();
> 
> -	of_platform_default_populate(NULL, NULL, parent);
> -

This slightly change the device register sequence as well as possible driver probe
sequence as a consequence.

Originally devices are registered in arch_initcall. Now it will be a bit later
in arch_initcall_sync and this may cause a bit risk if the code under the
default_populate want to access the device service provided by early probe.

Probably it's more safe to leave as it is unless you can double confirm 
there're no such code depends on accessing early probed devices as follows
before we can make the change.

>  	imx_anatop_init();
>  	cpu_is_imx6q() ?  imx6q_pm_init() : imx6dl_pm_init();
>  	imx6q_1588_init();

Regards
Dong Aisheng

> diff --git a/arch/arm/mach-imx/mach-imx6sl.c
> b/arch/arm/mach-imx/mach-imx6sl.c index 99be4225297a..9743bdbb68fa
> 100644
> --- a/arch/arm/mach-imx/mach-imx6sl.c
> +++ b/arch/arm/mach-imx/mach-imx6sl.c
> @@ -56,8 +56,6 @@ static void __init imx6sl_init_machine(void)
>  	if (parent == NULL)
>  		pr_warn("failed to initialize soc device\n");
> 
> -	of_platform_default_populate(NULL, NULL, parent);
> -
>  	if (cpu_is_imx6sl())
>  		imx6sl_fec_init();
>  	imx_anatop_init();
> diff --git a/arch/arm/mach-imx/mach-imx6sx.c
> b/arch/arm/mach-imx/mach-imx6sx.c index 7f52d9b1e8a4..19b9f2dd309e
> 100644
> --- a/arch/arm/mach-imx/mach-imx6sx.c
> +++ b/arch/arm/mach-imx/mach-imx6sx.c
> @@ -72,8 +72,6 @@ static void __init imx6sx_init_machine(void)
>  	if (parent == NULL)
>  		pr_warn("failed to initialize soc device\n");
> 
> -	of_platform_default_populate(NULL, NULL, parent);
> -
>  	imx6sx_enet_init();
>  	imx_anatop_init();
>  	imx6sx_pm_init();
> diff --git a/arch/arm/mach-imx/mach-imx6ul.c
> b/arch/arm/mach-imx/mach-imx6ul.c index 6cb8a22b617d..c57b9df791b1
> 100644
> --- a/arch/arm/mach-imx/mach-imx6ul.c
> +++ b/arch/arm/mach-imx/mach-imx6ul.c
> @@ -65,7 +65,6 @@ static void __init imx6ul_init_machine(void)
>  	if (parent == NULL)
>  		pr_warn("failed to initialize soc device\n");
> 
> -	of_platform_default_populate(NULL, NULL, parent);
>  	imx6ul_enet_init();
>  	imx_anatop_init();
>  	imx6ul_pm_init();
> --
> 2.16.4