linux-kernel - RE: [PATCH v2 2/4] iommu/arm-smmu: Invoke DT probe from arm_smmu_of

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Message-ID: <001f01d16a43$ef47d3b0$cdd77b10$@codeaurora.org>
Date:	Thu, 18 Feb 2016 17:30:08 +0530
From:	"Sricharan" <sricharan@...eaurora.org>
To:	"'Anup Patel'" <anup.patel@...adcom.com>,
	"'Catalin Marinas'" <catalin.marinas@....com>,
	"'Joerg Roedel'" <joro@...tes.org>,
	"'Will Deacon'" <will.deacon@....com>,
	"'Robin Murphy'" <Robin.Murphy@....com>,
	"'Linux IOMMU'" <iommu@...ts.linux-foundation.org>,
	"'Linux ARM Kernel'" <linux-arm-kernel@...ts.infradead.org>
Cc:	"'Mark Rutland'" <mark.rutland@....com>,
	"'Device Tree'" <devicetree@...r.kernel.org>,
	"'Scott Branden'" <sbranden@...adcom.com>,
	"'Pawel Moll'" <pawel.moll@....com>,
	"'Ian Campbell'" <ijc+devicetree@...lion.org.uk>,
	"'Ray Jui'" <rjui@...adcom.com>,
	"'Linux Kernel'" <linux-kernel@...r.kernel.org>,
	"'Vikram Prakash'" <vikramp@...adcom.com>,
	"'Rob Herring'" <robh+dt@...nel.org>,
	"'BCM Kernel Feedback'" <bcm-kernel-feedback-list@...adcom.com>,
	"'Kumar Gala'" <galak@...eaurora.org>
Subject: RE: [PATCH v2 2/4] iommu/arm-smmu: Invoke DT probe from arm_smmu_of_setup()

Hi,

> -----Original Message-----
> From: linux-arm-kernel [mailto:linux-arm-kernel-
> bounces@...ts.infradead.org] On Behalf Of Anup Patel
> Sent: Monday, February 08, 2016 10:48 AM
> To: Catalin Marinas; Joerg Roedel; Will Deacon; Robin Murphy; Sricharan R;
> Linux IOMMU; Linux ARM Kernel
> Cc: Mark Rutland; Device Tree; Scott Branden; Pawel Moll; Ian Campbell;
Ray
> Jui; Linux Kernel; Vikram Prakash; Rob Herring; BCM Kernel Feedback; Kumar
> Gala; Anup Patel
> Subject: [PATCH v2 2/4] iommu/arm-smmu: Invoke DT probe from
> arm_smmu_of_setup()
> 
> The SMMUv1/SMMUv2 driver is initialized very early using the
> IOMMU_OF_DECLARE() but the actual platform device is probed via normal
> DT probing.
> 
> This patch uses of_platform_device_create() from arm_smmu_of_setup() to
> ensure that SMMU platform device is probed immediately.
> 
> Signed-off-by: Anup Patel <anup.patel@...adcom.com>
> ---
>  drivers/iommu/arm-smmu.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c index
> 2c8f871..02cd67d 100644
> --- a/drivers/iommu/arm-smmu.c
> +++ b/drivers/iommu/arm-smmu.c
> @@ -40,6 +40,7 @@
>  #include <linux/of.h>
>  #include <linux/of_address.h>
>  #include <linux/of_iommu.h>
> +#include <linux/of_platform.h>
>  #include <linux/pci.h>
>  #include <linux/platform_device.h>
>  #include <linux/slab.h>
> @@ -1956,10 +1957,15 @@ static int __init arm_smmu_init(void)
> 
>  static int __init arm_smmu_of_setup(struct device_node *np)  {
> +	struct platform_device *pdev;
> 
>  	if (!init_done)
>  		arm_smmu_init();
> 
> +	pdev = of_platform_device_create(np, NULL, NULL);
> +	if (IS_ERR(pdev))
> +		return PTR_ERR(pdev);
> +
>  	of_iommu_set_ops(np, &arm_smmu_ops);

 A question here is,  There was a probe deferral series [1], to take care of
deferred
 probing of devices behind iommus. With that this sort of early device
probing during setup
 should not be required and also it clears other dependencies of iommus on
clocks, etc, if any.
 My intention was to check whats the right way to do this  ? (or) point me
to any updates 
 on the probe deferral series that I miss ?

[1]  http://lkml.iu.edu/hypermail/linux/kernel/1505.3/03280.html
 
Regards,
 Sricharan