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authorLudovic Desroches <ludovic.desroches@atmel.com>2012-03-28 12:28:33 +0200
committerChris Ball <cjb@laptop.org>2012-04-05 20:32:21 -0400
commit66292ad92c6d3f2f1c137a1c826b331ca8595dfd (patch)
tree8ddf84d30f17269a6ec4eed880b5db1491883e23 /drivers/mmc
parent9f4e8151dbbc4ca4d5dd7792666a50c137102204 (diff)
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>
Diffstat (limited to 'drivers/mmc')
-rw-r--r--drivers/mmc/host/atmel-mci.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/drivers/mmc/host/atmel-mci.c b/drivers/mmc/host/atmel-mci.c
index 9819dc09ce0..34080f590f6 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,