From 66292ad92c6d3f2f1c137a1c826b331ca8595dfd Mon Sep 17 00:00:00 2001 From: Ludovic Desroches Date: Wed, 28 Mar 2012 12:28:33 +0200 Subject: [PATCH] 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 Acked-by: Nicolas Ferre Cc: Signed-off-by: Chris Ball --- drivers/mmc/host/atmel-mci.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/drivers/mmc/host/atmel-mci.c b/drivers/mmc/host/atmel-mci.c index 9819dc09ce08..34080f590f69 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,