Subject: Re: [PATCH] of: iommu: make of_iommu_init() postcore_initcall_sync
To: Kefeng Wang <wangkefeng.wang@huawei.com>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
References: <1461403987-10697-1-git-send-email-wangkefeng.wang@huawei.com>
Cc: guohanjun@huawei.com, Arnd Bergmann <arnd@arndb.de>,
        Rich Felker <dalias@libc.org>, Rob Herring <robh+dt@kernel.org>,
        Robin Murphy <robin.murphy@arm.com>, Will Deacon <will.deacon@arm.com>
From: Marek Szyprowski <m.szyprowski@samsung.com>
Message-id: <7f0beaa3-442b-ad6e-129c-4c7cb22d9e12@samsung.com>
Date: Wed, 27 Apr 2016 14:08:38 +0200
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Hello,


On 2016-04-23 11:33, Kefeng Wang wrote:
> The of_iommu_init() is called multiple times by arch code,
> make it postcore_initcall_sync, then we can drop relevant
> calls fully.
>
> Note, the IOMMUs should have a chance to perform some basic
> initialisation before we start adding masters to them. So
> postcore_initcall_sync is good choice, it ensures of_iommu_init()
> called before of_platform_populate.
>
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: Marek Szyprowski <m.szyprowski@samsung.com>
> Cc: Rich Felker <dalias@libc.org>
> Cc: Rob Herring <robh+dt@kernel.org>
> Cc: Robin Murphy <robin.murphy@arm.com>
> Cc: Will Deacon <will.deacon@arm.com>
> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>

Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>

Works fine on Samsung Exynos 4412 based Odroid U3 board.

> ---
>   arch/arm/kernel/setup.c     | 2 --
>   arch/arm64/kernel/setup.c   | 2 --
>   arch/sh/boards/of-generic.c | 2 --
>   drivers/iommu/of_iommu.c    | 5 ++++-
>   include/linux/of_iommu.h    | 2 --
>   5 files changed, 4 insertions(+), 9 deletions(-)
>
> diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
> index 2c4bea3..18a29a0 100644
> --- a/arch/arm/kernel/setup.c
> +++ b/arch/arm/kernel/setup.c
> @@ -19,7 +19,6 @@
>   #include <linux/bootmem.h>
>   #include <linux/seq_file.h>
>   #include <linux/screen_info.h>
> -#include <linux/of_iommu.h>
>   #include <linux/of_platform.h>
>   #include <linux/init.h>
>   #include <linux/kexec.h>
> @@ -902,7 +901,6 @@ static int __init customize_machine(void)
>   	 * machine from the device tree, if no callback is provided,
>   	 * otherwise we would always need an init_machine callback.
>   	 */
> -	of_iommu_init();
>   	if (machine_desc->init_machine)
>   		machine_desc->init_machine();
>   #ifdef CONFIG_OF
> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
> index 9dc6776..e20b64f 100644
> --- a/arch/arm64/kernel/setup.c
> +++ b/arch/arm64/kernel/setup.c
> @@ -39,7 +39,6 @@
>   #include <linux/fs.h>
>   #include <linux/proc_fs.h>
>   #include <linux/memblock.h>
> -#include <linux/of_iommu.h>
>   #include <linux/of_fdt.h>
>   #include <linux/of_platform.h>
>   #include <linux/efi.h>
> @@ -365,7 +364,6 @@ void __init setup_arch(char **cmdline_p)
>   static int __init arm64_device_init(void)
>   {
>   	if (of_have_populated_dt()) {
> -		of_iommu_init();
>   		of_platform_populate(NULL, of_default_bus_match_table,
>   				     NULL, NULL);
>   	} else if (acpi_disabled) {
> diff --git a/arch/sh/boards/of-generic.c b/arch/sh/boards/of-generic.c
> index bf3a166..b4d4313 100644
> --- a/arch/sh/boards/of-generic.c
> +++ b/arch/sh/boards/of-generic.c
> @@ -11,7 +11,6 @@
>   #include <linux/of.h>
>   #include <linux/of_platform.h>
>   #include <linux/of_fdt.h>
> -#include <linux/of_iommu.h>
>   #include <linux/clocksource.h>
>   #include <linux/irqchip.h>
>   #include <linux/clk-provider.h>
> @@ -185,7 +184,6 @@ static int __init sh_of_device_init(void)
>   {
>   	pr_info("SH generic board support: populating platform devices\n");
>   	if (of_have_populated_dt()) {
> -		of_iommu_init();
>   		of_platform_populate(NULL, of_default_bus_match_table,
>   				     NULL, NULL);
>   	} else {
> diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c
> index 5fea665..04cc80f 100644
> --- a/drivers/iommu/of_iommu.c
> +++ b/drivers/iommu/of_iommu.c
> @@ -174,7 +174,7 @@ err_put_node:
>   	return NULL;
>   }
>   
> -void __init of_iommu_init(void)
> +static int __init of_iommu_init(void)
>   {
>   	struct device_node *np;
>   	const struct of_device_id *match, *matches = &__iommu_of_table;
> @@ -186,4 +186,7 @@ void __init of_iommu_init(void)
>   			pr_err("Failed to initialise IOMMU %s\n",
>   				of_node_full_name(np));
>   	}
> +
> +	return 0;
>   }
> +postcore_initcall_sync(of_iommu_init);
> diff --git a/include/linux/of_iommu.h b/include/linux/of_iommu.h
> index ffbe470..e2c2e71 100644
> --- a/include/linux/of_iommu.h
> +++ b/include/linux/of_iommu.h
> @@ -11,7 +11,6 @@ extern int of_get_dma_window(struct device_node *dn, const char *prefix,
>   			     int index, unsigned long *busno, dma_addr_t *addr,
>   			     size_t *size);
>   
> -extern void of_iommu_init(void);
>   extern struct iommu_ops *of_iommu_configure(struct device *dev,
>   					struct device_node *master_np);
>   
> @@ -24,7 +23,6 @@ static inline int of_get_dma_window(struct device_node *dn, const char *prefix,
>   	return -EINVAL;
>   }
>   
> -static inline void of_iommu_init(void) { }
>   static inline struct iommu_ops *of_iommu_configure(struct device *dev,
>   					 struct device_node *master_np)
>   {

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland