Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Nick Hu <nickhu@andestech.com>
To:     <greentime@andestech.com>, <palmer@sifive.com>,
        <albert@sifive.com>, <linux-riscv@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>, <hch@infradead.org>
CC:     Nick Hu <nickhu@andestech.com>, <green.hu@gmail.com>
Subject: [PATCH v3] riscv: Fix udelay in RV32.
Date:   Thu, 30 May 2019 15:01:17 +0800
Message-ID: <67bfbb11e64273427b125528a4e2bc83b5efe70b.1559199430.git.nickhu@andestech.com>
MIME-Version: 1.0
Content-Type: text/plain
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

In RV32, udelay would delay the wrong cycle. When it shifts right
"UDELAY_SHITFT" bits, it either delays 0 cycle or 1 cycle. It only works
correctly in RV64. Because the 'ucycles' always needs to be 64 bits
variable.

Signed-off-by: Nick Hu <nickhu@andestech.com>
Reviewed-by: Palmer Dabbelt <palmer@sifive.com>
---
 arch/riscv/lib/delay.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/riscv/lib/delay.c b/arch/riscv/lib/delay.c
index dce8ae24c6d3..ee6853c1e341 100644
--- a/arch/riscv/lib/delay.c
+++ b/arch/riscv/lib/delay.c
@@ -88,7 +88,7 @@ EXPORT_SYMBOL(__delay);
 
 void udelay(unsigned long usecs)
 {
-	unsigned long ucycles = usecs * lpj_fine * UDELAY_MULT;
+	u64 ucycles = (u64)usecs * lpj_fine * UDELAY_MULT;
 
 	if (unlikely(usecs > MAX_UDELAY_US)) {
 		__delay((u64)usecs * riscv_timebase / 1000000ULL);
-- 
2.17.0