linux-kernel - [PATCH 1/1]mmc: fix division by zero when calculate mmc erase time

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Message-ID: <20110224111801.GA7169@intel.com>
Date:	Thu, 24 Feb 2011 19:18:01 +0800
From:	Chuanxiao Dong <chuanxiao.dong@...el.com>
To:	linux-mmc@...r.kernel.org, cjb@...top.org
Cc:	adrian.hunter@...ia.com, linus.walleij@...aro.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 1/1]mmc: fix division by zero when calculate mmc erase time

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 34a7e8c..12d0eb8 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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