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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>
This commit is contained in:
Ludovic Desroches 2012-03-28 12:28:33 +02:00 committed by Chris Ball
parent 9f4e8151db
commit 66292ad92c
1 changed files with 8 additions and 1 deletions
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9
drivers/mmc/host/atmel-mci.c
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@ -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,