[PATCH v2 2/4] iommu/arm-smmu: Invoke DT probe from arm_smmu_of_setup()

On Thu, Feb 18, 2016 at 5:30 PM, Sricharan [off-list ref] wrote:

Hi,

quoted

-----Original Message-----
From: linux-arm-kernel [mailto:linux-arm-kernel-
bounces at lists.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

quoted

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 <redacted>
---
 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

I think probe deferral is better way of handling this. I will drop this
patch.

Thanks,
Anup