On 03/28/2012 12:28 PM, ludovic.desroches@xxxxxxxxx :
> From: Ludovic Desroches <ludovic.desroches@xxxxxxxxx>
>
> 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@xxxxxxxxx>
Acked-by: Nicolas Ferre <nicolas.ferre@xxxxxxxxx>
> Cc: stable <stable@xxxxxxxxxxxxxxx>
> ---
> 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,
--
Nicolas Ferre
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