Messages in this thread Patch in this message | | | Date | Wed, 11 Apr 2012 16:13:34 -0700 | From | Greg KH <> | Subject | [ 27/42] mmc: atmel-mci: correct data timeout computation |
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3.0-stable review patch. If anyone has any objections, please let me know.
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From: Ludovic Desroches <ludovic.desroches@atmel.com>
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>
--- drivers/mmc/host/atmel-mci.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
--- a/drivers/mmc/host/atmel-mci.c +++ b/drivers/mmc/host/atmel-mci.c @@ -468,7 +468,14 @@ err: static inline unsigned int 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,
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