Messages in this thread Patch in this message | | | From | Arnd Bergmann <> | Subject | [PATCH] [RESEND] firewire: ohci: stop using get_seconds() for BUS_TIME | Date | Wed, 11 Jul 2018 14:49:10 +0200 |
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The ohci driver uses the get_seconds() function to implement the 32-bit CSR_BUS_TIME register. This was added in 2010 commit a48777e03ad5 ("firewire: add CSR BUS_TIME support").
As get_seconds() returns a 32-bit value (on 32-bit architectures), it seems like a good fit for that register, but it is also deprecated because of the y2038/y2106 overflow problem, and should be replaced throughout the kernel with either ktime_get_real_seconds() or ktime_get_seconds().
I'm using the latter here, which uses monotonic time. This has the advantage of behaving better during concurrent settimeofday() updates or leap second adjustments and won't overflow a 32-bit integer, but the downside of using CLOCK_MONOTONIC instead of CLOCK_REALTIME is that the observed values are not related to external clocks.
If we instead need UTC but can live with clock jumps or overflows, then we should use ktime_get_real_seconds() instead, retaining the existing behavior.
Reviewed-by: Clemens Ladisch <clemens@ladisch.de> Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- I notice that Stefan Richter has not been active on the mailing lists since February 2018.
Andrew, could you pick it up in the meantime? --- drivers/firewire/ohci.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/firewire/ohci.c b/drivers/firewire/ohci.c index 45c048751f3b..5125841ea338 100644 --- a/drivers/firewire/ohci.c +++ b/drivers/firewire/ohci.c @@ -1765,7 +1765,7 @@ static u32 update_bus_time(struct fw_ohci *ohci) if (unlikely(!ohci->bus_time_running)) { reg_write(ohci, OHCI1394_IntMaskSet, OHCI1394_cycle64Seconds); - ohci->bus_time = (lower_32_bits(get_seconds()) & ~0x7f) | + ohci->bus_time = (lower_32_bits(ktime_get_seconds()) & ~0x7f) | (cycle_time_seconds & 0x40); ohci->bus_time_running = true; } -- 2.9.0
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