[PATCH 7/8] iommu: of: Handle IOMMU lookup failure with deferred probing or error

Hi Marek,

Hi Sricharan,

On 2016-08-09 00:49, Sricharan R wrote:

quoted

From: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

Failures to look up an IOMMU when parsing the DT iommus property need to
be handled separately from the .of_xlate() failures to support deferred
probing.

The lack of a registered IOMMU can be caused by the lack of a driver for
the IOMMU, the IOMMU device probe not having been performed yet, having
been deferred, or having failed.

The first case occurs when the device tree describes the bus master and
IOMMU topology correctly but no device driver exists for the IOMMU yet
or the device driver has not been compiled in. Return NULL, the caller
will configure the device without an IOMMU.

The second and third cases are handled by deferring the probe of the bus
master device which will eventually get reprobed after the IOMMU.

The last case is currently handled by deferring the probe of the bus
master device as well. A mechanism to either configure the bus master
device without an IOMMU or to fail the bus master device probe depending
on whether the IOMMU is optional or mandatory would be a good
enhancement.

Signed-off-by: Laurent Pinchart

[off-list ref]

It is a common practice to briefly describe here what has been changed
since the original patch if you have modified it (see commit
855ed04a3758b205e84b269f92d26ab36ed8e2f7 for the example).

 Sorry i missed updating it. i will update the log.

quoted

Signed-off-by: Sricharan R <redacted>
---
 drivers/iommu/of_iommu.c | 21 +++++++++++++++++----
 drivers/of/device.c      |  2 ++
 2 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c
index 4c4219d..3994cf5 100644
--- a/drivers/iommu/of_iommu.c
+++ b/drivers/iommu/of_iommu.c

@@ -149,7 +149,7 @@ const struct iommu_ops *of_iommu_configure(struct

device *dev,

quoted

 {
     struct of_phandle_args iommu_spec;
     struct device_node *np = NULL;
-    struct iommu_ops *ops = NULL;
+    const struct iommu_ops *ops = NULL;
     int idx = 0;

     if (dev_is_pci(dev)) {

@@ -189,8 +189,21 @@ const struct iommu_ops

*of_iommu_configure(struct device *dev,

quoted

         np = iommu_spec.np;
         ops = of_iommu_get_ops(np);

-        if (!ops || !ops->of_xlate || ops->of_xlate(dev, &iommu_spec))
+        if (!ops) {
+            const struct of_device_id *oid;
+
+            oid = of_match_node(&__iommu_of_table, np);
+            ops = oid ? ERR_PTR(-EPROBE_DEFER) : NULL;
             goto err_put_node;
+        }
+
+        if (!ops->of_xlate || ops->of_xlate(dev, &iommu_spec)) {
+            ops = NULL;
+            goto err_put_node;
+        }
+
+        if (ops->add_device)
+            ops = ops->add_device(dev) ? ops : NULL;

ops->add_device() returns ZERO on success or error code on failure, so
the above
line should be changed to:
            ops = (ops->add_device(dev) == 0) ? ops : NULL;

 Yes, i fixed it while testing, but somehow have missed it while sending it.
  will fix it.

Regards,
 Sricharan