linux-kernel - [PATCH v4 3/3]mmc: fix division by zero when cal erase timeout

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Message-ID: <20110212062226.GD25519@intel.com>
Date:	Sat, 12 Feb 2011 14:22:26 +0800
From:	Chuanxiao Dong <chuanxiao.dong@...el.com>
To:	linux-mmc@...r.kernel.org, cjb@...top.org
Cc:	linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
	adrian.hunter@...ia.com
Subject: [PATCH v4 3/3]mmc: fix division by zero when cal erase timeout

Since if clock gating feature is enabled, the clock frequency may be zero when
host clock is gated. In such scenario, mmc_set_mmc_erase_timeout() may have a
division by zero bug.

So this patch used mmc_host_clk_rate() to fix this.

Signed-off-by: Chuanxiao Dong <chuanxiao.dong@...el.com>
---
 drivers/mmc/core/core.c |   10 ++++++++--
 1 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 0eb27aa..2f4576d 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -1201,8 +1201,14 @@ static void mmc_set_mmc_erase_timeout(struct mmc_card *card,
 		 * less but not that much less, so fudge it by multiplying by 2.
 		 */
 		timeout_clks <<= 1;
-		timeout_us += (timeout_clks * 1000) /
-			      (card->host->ios.clock / 1000);
+
+		/*
+		 * at this moment, host controller maybe clock gated, so make
+		 * sure we can get a correct host clock freq.
+		 */
+		if (mmc_host_clk_rate(card->host))
+			timeout_us += (timeout_clks * 1000) /
+				      (mmc_host_clk_rate(card->host) / 1000);
 
 		erase_timeout = timeout_us / 1000;
 
-- 
1.6.6.1

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