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iommu/mediatek-v1: Fix off-by-one in MT2701_LARB_NR_MAX

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The mt2701_m4u_in_larb[] array contains 4 (for LARB0 to LARB3)
elements, meaning mt2701_m4u_to_larb() can legitimately return 3.
The current check `if (larbid >= MT2701_LARB_NR_MAX)` incorrectly
rejects valid LARB3 with -EINVAL.

Fix this off-by-one error by updating MT2701_LARB_NR_MAX to 4.

Note that this does not cause immediate issues with the current
mt2701.dtsi and mt7623n.dtsi because it only defines 3 LARBs:
    mediatek,larbs = <&larb0 &larb1 &larb2>;
Thus, larbid never reaches 3 in the existing upstream device tree.

Fixes: de78657e16 ("iommu/mediatek: Fix NULL pointer dereference when printing dev_name")
Signed-off-by: Akari Tsuyukusa <akkun11.open@gmail.com>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
This commit is contained in:
Akari Tsuyukusa 2026-06-29 23:59:44 +09:00 committed by Joerg Roedel
parent 8cdeaa50ea
commit aebaa93f3d
1 changed files with 1 additions and 1 deletions
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2
drivers/iommu/mtk_iommu_v1.c
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@ -88,7 +88,7 @@ struct dma_iommu_mapping {
/* MTK generation one iommu HW only support 4K size mapping */
#define MT2701_IOMMU_PAGE_SHIFT 12
#define MT2701_IOMMU_PAGE_SIZE (1UL << MT2701_IOMMU_PAGE_SHIFT)
#define MT2701_LARB_NR_MAX 3
#define MT2701_LARB_NR_MAX 4
/*
* MTK m4u support 4GB iova address space, and only support 4K page