linux-kernel - [PATCH] iommu/rockchip: Fix "is stall active" check

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Message-Id: <1459865146-25308-1-git-send-email-john@metanate.com>
Date:	Tue,  5 Apr 2016 15:05:46 +0100
From:	John Keeping <john@...anate.com>
To:	Joerg Roedel <joro@...tes.org>
Cc:	Heiko Stuebner <heiko@...ech.de>, iommu@...ts.linux-foundation.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org,
	John Keeping <john@...anate.com>
Subject: [PATCH] iommu/rockchip: Fix "is stall active" check

Since commit cd6438c5f844 ("iommu/rockchip: Reconstruct to support multi
slaves") rk_iommu_is_stall_active() always returns false because the
bitwise AND operates on the boolean flag promoted to an integer and a
value that is either zero or BIT(2).

Explicitly convert the right-hand value to a boolean so that both sides
are guaranteed to be either zero or one.

rk_iommu_is_paging_enabled() does not suffer from the same problem since
RK_MMU_STATUS_PAGING_ENABLED is BIT(0), but let's apply the same change
for consistency and to make it clear that it's correct without needing
to lookup the value.

Fixes: cd6438c5f844 ("iommu/rockchip: Reconstruct to support multi slaves")
Signed-off-by: John Keeping <john@...anate.com>
---
 drivers/iommu/rockchip-iommu.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/iommu/rockchip-iommu.c b/drivers/iommu/rockchip-iommu.c
index a6f593a0a29e..5710a06c3049 100644
--- a/drivers/iommu/rockchip-iommu.c
+++ b/drivers/iommu/rockchip-iommu.c
@@ -315,8 +315,8 @@ static bool rk_iommu_is_stall_active(struct rk_iommu *iommu)
 	int i;
 
 	for (i = 0; i < iommu->num_mmu; i++)
-		active &= rk_iommu_read(iommu->bases[i], RK_MMU_STATUS) &
-					RK_MMU_STATUS_STALL_ACTIVE;
+		active &= !!(rk_iommu_read(iommu->bases[i], RK_MMU_STATUS) &
+					   RK_MMU_STATUS_STALL_ACTIVE);
 
 	return active;
 }
@@ -327,8 +327,8 @@ static bool rk_iommu_is_paging_enabled(struct rk_iommu *iommu)
 	int i;
 
 	for (i = 0; i < iommu->num_mmu; i++)
-		enable &= rk_iommu_read(iommu->bases[i], RK_MMU_STATUS) &
-					RK_MMU_STATUS_PAGING_ENABLED;
+		enable &= !!(rk_iommu_read(iommu->bases[i], RK_MMU_STATUS) &
+					   RK_MMU_STATUS_PAGING_ENABLED);
 
 	return enable;
 }
-- 
2.8.0.rc4.238.g874082a