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Subject[PATCH 2/2] iommu/rockchip: Move irq request past pm_runtime_enable
Date
Enabling the interrupt early, before power has been applied to the
device, can result in an interrupt being delivered too early if:

- the IOMMU shares an interrupt with a VOP
- the VOP has a pending interrupt (after a kexec, for example)

In these conditions, we end-up taking the interrupt without
the IOMMU being ready to handle the interrupt (not powered on).

Moving the interrupt request past the pm_runtime_enable() call
makes sure we can at least access the IOMMU registers. Note that
this is only a partial fix, and that the VOP interrupt will still
be screaming until the VOP driver kicks in, which advocates for
a more synchronized interrupt enabling/disabling approach.

Fixes: 0f181d3cf7d98 ("iommu/rockchip: Add runtime PM support")
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
drivers/iommu/rockchip-iommu.c | 24 +++++++++++++-----------
1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/drivers/iommu/rockchip-iommu.c b/drivers/iommu/rockchip-iommu.c
index 4e0f9b61cd7f..2b1724e8d307 100644
--- a/drivers/iommu/rockchip-iommu.c
+++ b/drivers/iommu/rockchip-iommu.c
@@ -1161,17 +1161,6 @@ static int rk_iommu_probe(struct platform_device *pdev)
if (iommu->num_mmu == 0)
return PTR_ERR(iommu->bases[0]);

- i = 0;
- while ((irq = platform_get_irq(pdev, i++)) != -ENXIO) {
- if (irq < 0)
- return irq;
-
- err = devm_request_irq(iommu->dev, irq, rk_iommu_irq,
- IRQF_SHARED, dev_name(dev), iommu);
- if (err)
- return err;
- }
-
iommu->reset_disabled = device_property_read_bool(dev,
"rockchip,disable-mmu-reset");

@@ -1228,6 +1217,19 @@ static int rk_iommu_probe(struct platform_device *pdev)

pm_runtime_enable(dev);

+ i = 0;
+ while ((irq = platform_get_irq(pdev, i++)) != -ENXIO) {
+ if (irq < 0)
+ return irq;
+
+ err = devm_request_irq(iommu->dev, irq, rk_iommu_irq,
+ IRQF_SHARED, dev_name(dev), iommu);
+ if (err) {
+ pm_runtime_disable(dev);
+ goto err_remove_sysfs;
+ }
+ }
+
return 0;
err_remove_sysfs:
iommu_device_sysfs_remove(&iommu->iommu);
--
2.18.0
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