linux-kernel - [PATCH] iommu/mediatek: fix out-of-range warning with clang

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Message-Id: <20210927121857.941160-1-arnd@kernel.org>
Date:   Mon, 27 Sep 2021 14:18:44 +0200
From:   Arnd Bergmann <arnd@...nel.org>
To:     Yong Wu <yong.wu@...iatek.com>, Joerg Roedel <joro@...tes.org>,
        Will Deacon <will@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Tomasz Figa <tfiga@...omium.org>,
        Robin Murphy <robin.murphy@....com>,
        iommu@...ts.linux-foundation.org,
        linux-mediatek@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        llvm@...ts.linux.dev
Subject: [PATCH] iommu/mediatek: fix out-of-range warning with clang

From: Arnd Bergmann <arnd@...db.de>

clang-14 notices that a comparison is never true when
CONFIG_PHYS_ADDR_T_64BIT is disabled:

drivers/iommu/mtk_iommu.c:553:34: error: result of comparison of constant 5368709120 with expression of type 'phys_addr_t' (aka 'unsigned int') is always false [-Werror,-Wtautological-constant-out-of-range-compare]
        if (dom->data->enable_4GB && pa >= MTK_IOMMU_4GB_MODE_REMAP_BASE)
                                     ~~ ^  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Add an explicit check for the type of the variable to skip the check
and the warning in that case.

Fixes: b4dad40e4f35 ("iommu/mediatek: Adjust the PA for the 4GB Mode")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 drivers/iommu/mtk_iommu.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
index d837adfd1da5..25b834104790 100644
--- a/drivers/iommu/mtk_iommu.c
+++ b/drivers/iommu/mtk_iommu.c
@@ -550,7 +550,9 @@ static phys_addr_t mtk_iommu_iova_to_phys(struct iommu_domain *domain,
 	phys_addr_t pa;
 
 	pa = dom->iop->iova_to_phys(dom->iop, iova);
-	if (dom->data->enable_4GB && pa >= MTK_IOMMU_4GB_MODE_REMAP_BASE)
+	if (IS_ENABLED(CONFIG_PHYS_ADDR_T_64BIT) &&
+	    dom->data->enable_4GB &&
+	    pa >= MTK_IOMMU_4GB_MODE_REMAP_BASE)
 		pa &= ~BIT_ULL(32);
 
 	return pa;
-- 
2.29.2