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| author | Ludovic Desroches <ludovic.desroches@atmel.com> | 2012-03-28 12:28:33 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2012-04-13 09:13:55 -0700 |
| commit | ac96adba1ac5899a5665a22768fdbe6b88656362 (patch) | |
| tree | 9d14561ae9fffe4949717a943867532a597ed7cf | |
| parent | 56d6515e51207145a9ee999c2373cb0c2ffd95c8 (diff) | |
| download | lwn-ac96adba1ac5899a5665a22768fdbe6b88656362.tar.gz lwn-ac96adba1ac5899a5665a22768fdbe6b88656362.zip | |
mmc: atmel-mci: correct data timeout computation
commit 66292ad92c6d3f2f1c137a1c826b331ca8595dfd upstream.
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>
Signed-off-by: Chris Ball <cjb@laptop.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | 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 e4449a54ae8f..3a57964b5e14 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, |