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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Paul Burton <paul.burton@mips.com>,
        Huacai Chen <chenhc@lemote.com>,
        James Hogan <jhogan@kernel.org>,
        Ralf Baechle <ralf@linux-mips.org>, linux-mips@linux-mips.org,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.18 160/235] MIPS: loongson64: cs5536: Fix PCI_OHCI_INT_REG reads
Date:   Mon, 24 Sep 2018 13:52:26 +0200
Message-Id: <20180924113121.162375180@linuxfoundation.org>
In-Reply-To: <20180924113103.999624566@linuxfoundation.org>
References: <20180924113103.999624566@linuxfoundation.org>
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4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Paul Burton <paul.burton@mips.com>

[ Upstream commit cd87668d601f622e0ebcfea4f78d116d5f572f4d ]

The PCI_OHCI_INT_REG case in pci_ohci_read_reg() contains the following
if statement:

  if ((lo & 0x00000f00) == CS5536_USB_INTR)

CS5536_USB_INTR expands to the constant 11, which gives us the following
condition which can never evaluate true:

  if ((lo & 0xf00) == 11)

At least when using GCC 8.1.0 this falls foul of the tautoligcal-compare
warning, and since the code is built with the -Werror flag the build
fails.

Fix this by shifting lo right by 8 bits in order to match the
corresponding PCI_OHCI_INT_REG case in pci_ohci_write_reg().

Signed-off-by: Paul Burton <paul.burton@mips.com>
Patchwork: https://patchwork.linux-mips.org/patch/19861/
Cc: Huacai Chen <chenhc@lemote.com>
Cc: James Hogan <jhogan@kernel.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/mips/loongson64/common/cs5536/cs5536_ohci.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/mips/loongson64/common/cs5536/cs5536_ohci.c
+++ b/arch/mips/loongson64/common/cs5536/cs5536_ohci.c
@@ -138,7 +138,7 @@ u32 pci_ohci_read_reg(int reg)
 		break;
 	case PCI_OHCI_INT_REG:
 		_rdmsr(DIVIL_MSR_REG(PIC_YSEL_LOW), &hi, &lo);
-		if ((lo & 0x00000f00) == CS5536_USB_INTR)
+		if (((lo >> PIC_YSEL_LOW_USB_SHIFT) & 0xf) == CS5536_USB_INTR)
 			conf_data = 1;
 		break;
 	default: