mmc: sdhci: fix data timeout (part 2)

commit 7f05538af71c7d30b5fc821cbe9f318edc645961 upstream.

The calculation for the timeout based on the number of card clocks is
incorrect.  The calculation assumed:

	timeout in microseconds = clock cycles / clock in Hz

which is clearly a several orders of magnitude wrong.  Fix this by
multiplying the clock cycles by 1000000 prior to dividing by the Hz
based clock.  Also, as per part 1, ensure that the division rounds
up.

As this needs 64-bit math via do_div(), avoid it if the clock cycles
is zero.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Tested-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index f8d30a53f77ed81958bba9c9c55f75afd2c02606..a595d7e289ab7fe7c3ff33b6d2ca42a7b2034cac 100644 (file)
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -661,8 +661,19 @@ static u8 sdhci_calc_timeout(struct sdhci_host *host, struct mmc_command *cmd)
                target_timeout = cmd->busy_timeout * 1000;
        else {
                target_timeout = DIV_ROUND_UP(data->timeout_ns, 1000);
-               if (host->clock)
-                       target_timeout += data->timeout_clks / host->clock;
+               if (host->clock && data->timeout_clks) {
+                       unsigned long long val;
+
+                       /*
+                        * data->timeout_clks is in units of clock cycles.
+                        * host->clock is in Hz.  target_timeout is in us.
+                        * Hence, us = 1000000 * cycles / Hz.  Round up.
+                        */
+                       val = 1000000 * data->timeout_clks;
+                       if (do_div(val, host->clock))
+                               target_timeout++;
+                       target_timeout += val;
+               }
        }
 
        /*