[3.16.y-ckt stable] Patch "mmc: sdhci: fix data timeout (part 2)" has been added to the 3.16.y-ckt tree

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    mmc: sdhci: fix data timeout (part 2)

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt27.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

---8<------------------------------------------------------------

>From 516c71c7447eb614dbff6ffc2fec13cb472d051a Mon Sep 17 00:00:00 2001
From: Russell King <rmk+kernel at arm.linux.org.uk>
Date: Tue, 26 Jan 2016 13:41:04 +0000
Subject: mmc: sdhci: fix data timeout (part 2)

commit 7f05538af71c7d30b5fc821cbe9f318edc645961 upstream.

The calculation for the timeout based on the number of card clocks is
incorrect.  The calculation assumed:

	timeout in microseconds = clock cycles / clock in Hz

which is clearly a several orders of magnitude wrong.  Fix this by
multiplying the clock cycles by 1000000 prior to dividing by the Hz
based clock.  Also, as per part 1, ensure that the division rounds
up.

As this needs 64-bit math via do_div(), avoid it if the clock cycles
is zero.

Signed-off-by: Russell King <rmk+kernel at arm.linux.org.uk>
Signed-off-by: Adrian Hunter <adrian.hunter at intel.com>
Tested-by: Gregory CLEMENT <gregory.clement at free-electrons.com>
Signed-off-by: Ulf Hansson <ulf.hansson at linaro.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/mmc/host/sdhci.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index f8d30a53f77e..a595d7e289ab 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -661,8 +661,19 @@ static u8 sdhci_calc_timeout(struct sdhci_host *host, struct mmc_command *cmd)
 		target_timeout = cmd->busy_timeout * 1000;
 	else {
 		target_timeout = DIV_ROUND_UP(data->timeout_ns, 1000);
-		if (host->clock)
-			target_timeout += data->timeout_clks / host->clock;
+		if (host->clock && data->timeout_clks) {
+			unsigned long long val;
+
+			/*
+			 * data->timeout_clks is in units of clock cycles.
+			 * host->clock is in Hz.  target_timeout is in us.
+			 * Hence, us = 1000000 * cycles / Hz.  Round up.
+			 */
+			val = 1000000 * data->timeout_clks;
+			if (do_div(val, host->clock))
+				target_timeout++;
+			target_timeout += val;
+		}
 	}

 	/*