[PATCH v2 3/7] iommu/exynos: Set correct dma mask for SysMMU v5+

From: Sam Protsenko
Date: Sun Jul 10 2022 - 19:06:25 EST


SysMMU v5+ supports 36 bit physical address space. Set corresponding DMA
mask to avoid falling back to SWTLBIO usage in dma_map_single() because
of failed dma_capable() check.

The original code for this fix was suggested by Marek.

Signed-off-by: Sam Protsenko <semen.protsenko@xxxxxxxxxx>
Co-developed-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
---
Changes in v2:
- Handled failed dma_set_mask() call
- Replaced "Originally-by" tag by "Co-developed-by" + SoB tags

drivers/iommu/exynos-iommu.c | 10 ++++++++++
1 file changed, 10 insertions(+)

diff --git a/drivers/iommu/exynos-iommu.c b/drivers/iommu/exynos-iommu.c
index c85db9dab851..494f7d7aa9c5 100644
--- a/drivers/iommu/exynos-iommu.c
+++ b/drivers/iommu/exynos-iommu.c
@@ -646,6 +646,14 @@ static int exynos_sysmmu_probe(struct platform_device *pdev)
}
}

+ if (MMU_MAJ_VER(data->version) >= 5) {
+ ret = dma_set_mask(dev, DMA_BIT_MASK(36));
+ if (ret) {
+ dev_err(dev, "Unable to set DMA mask: %d\n", ret);
+ goto err_dma_set_mask;
+ }
+ }
+
/*
* use the first registered sysmmu device for performing
* dma mapping operations on iommu page tables (cpu cache flush)
@@ -657,6 +665,8 @@ static int exynos_sysmmu_probe(struct platform_device *pdev)

return 0;

+err_dma_set_mask:
+ iommu_device_unregister(&data->iommu);
err_iommu_register:
iommu_device_sysfs_remove(&data->iommu);
return ret;
--
2.30.2