On Tue, May 23, 2017 at 02:31:17PM +0530, Sricharan R wrote:

Hi Lorenzo,

On 5/23/2017 2:22 PM, Lorenzo Pieralisi wrote:

quoted

On Tue, May 23, 2017 at 02:26:10AM -0400, Nate Watterson wrote:

quoted

Hi Sricharan,

On 4/10/2017 7:21 AM, Sricharan R wrote:

quoted

This is an equivalent to the DT's handling of the iommu master's probe
with deferred probing when the corrsponding iommu is not probed yet.
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 firmware 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.

Tested-by: Hanjun Guo <redacted>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
[Lorenzo: Added fixes for dma_coherent_mask overflow, acpi_dma_configure
          called multiple times for same device]
Signed-off-by: Lorenzo Pieralisi <redacted>
Signed-off-by: Sricharan R <redacted>
---
 drivers/acpi/arm64/iort.c  | 33 ++++++++++++++++++++++++++++++++-
 drivers/acpi/scan.c        | 11 ++++++++---
 drivers/base/dma-mapping.c |  2 +-
 include/acpi/acpi_bus.h    |  2 +-
 include/linux/acpi.h       |  7 +++++--
 5 files changed, 47 insertions(+), 8 deletions(-)

diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
index 3dd9ec3..e323ece 100644
--- a/drivers/acpi/arm64/iort.c
+++ b/drivers/acpi/arm64/iort.c

@@ -543,6 +543,14 @@ static const struct iommu_ops *iort_iommu_xlate(struct device *dev,
 	const struct iommu_ops *ops = NULL;
 	int ret = -ENODEV;
 	struct fwnode_handle *iort_fwnode;
+	struct iommu_fwspec *fwspec = dev->iommu_fwspec;
+
+	/*
+	 * If we already translated the fwspec there
+	 * is nothing left to do, return the iommu_ops.
+	 */
+	if (fwspec && fwspec->ops)
+		return fwspec->ops;

Is this logic strictly required? It breaks masters with multiple SIDs
as only the first SID is actually added to the master's fwspec.

My bad, that's indeed a silly bug I introduced. Please let me know if the
patch below fixes it, we will send it upstream shortly.

oops, i think emails crossed. Please let me know if you are ok to add
this to the other fixes.

No worries, yes I am ok thanks but please give Nate some time to report
back to make sure the diff I sent actually fixes the problem.

Apologies for the breakage.

Lorenzo

Regards,
 Sricharan