[PATCH v2 1/3] mmc: atmel-mci: correct data timeout computation
From: ludovic.desroches at atmel.com <hidden>
Date: 2012-03-28 10:28:33
Also in:
linux-mmc
Subsystem:
microchip mmc/sd/sdio mci driver, multimedia card (mmc), secure digital (sd) and sdio subsystem, the rest · Maintainers:
Aubin Constans, Ulf Hansson, Linus Torvalds
From: Ludovic Desroches <redacted> 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 <redacted> Cc: stable <redacted> --- drivers/mmc/host/atmel-mci.c | 9 ++++++++- 1 files changed, 8 insertions(+), 1 deletions(-)
diff --git a/drivers/mmc/host/atmel-mci.c b/drivers/mmc/host/atmel-mci.c
index e4449a5..3a57964 100644
--- a/drivers/mmc/host/atmel-mci.c
+++ b/drivers/mmc/host/atmel-mci.c@@ -480,7 +480,14 @@ 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,
--
1.7.5.4