From: Ludovic Desroches <ludovic.desroches@atmel.com>
Date: Wed, 28 Mar 2012 10:28:33 +0000 (+0200)
Subject: mmc: atmel-mci: correct data timeout computation
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=66292ad92c6d3f2f1c137a1c826b331ca8595dfd;p=linux.git
mmc: atmel-mci: correct data timeout computation
The HSMCI operates at a rate of up to Master Clock divided by two.
Moreover previous calculation can cause overflows and so wrong
timeouts.
Signed-off-by: Ludovic Desroches <ludovic.desroches@atmel.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Chris Ball <cjb@laptop.org>
---
diff --git a/drivers/mmc/host/atmel-mci.c b/drivers/mmc/host/atmel-mci.c
index 9819dc09ce08d..34080f590f694 100644
--- a/drivers/mmc/host/atmel-mci.c
+++ b/drivers/mmc/host/atmel-mci.c
@@ -482,7 +482,14 @@ err:
static inline unsigned int atmci_ns_to_clocks(struct atmel_mci *host,
unsigned int ns)
{
- return (ns * (host->bus_hz / 1000000) + 999) / 1000;
+ /*
+ * It is easier here to use us instead of ns for the timeout,
+ * it prevents from overflows during calculation.
+ */
+ unsigned int us = DIV_ROUND_UP(ns, 1000);
+
+ /* Maximum clock frequency is host->bus_hz/2 */
+ return us * (DIV_ROUND_UP(host->bus_hz, 2000000));
}
static void atmci_set_timeout(struct atmel_mci *host,