Hi Alexandre,
On Tue, Apr 24, 2018 at 12:37 PM, Alexandre Belloni
<alexandre.belloni@xxxxxxxxxxx> wrote:
On 24/04/2018 12:06:30+0200, Geert Uytterhoeven wrote:
On Mon, Apr 23, 2018 at 3:02 AM, Finn Thain <fthain@xxxxxxxxxxxxxxxxxxx> wrote:
This fixes a bug in read_persistent_clock() which causes the system
clock to lag the Real Time Clock by one month. The problem was noticed
on a Mac, but theoretically it must also affect Atari, BVME6000 and Q40.
The tm_mon value in the struct rtc_time passed to mach_hwclk() is
zero-based, and atari_mste_hwclk(), atari_tt_hwclk(), bvme6000_hwclk(),
mac_hwclk() and q40_hwclk() all make this adjustment. Unfortunately,
dn_dummy_hwclk(), mvme147_hwclk(), mvme16x_hwclk(), sun3_hwclk() and
sun3x_hwclk() fail to decrement tm_mon.
Bring these platforms into line and fix read_persistent_clock() so it
works correctly on all m68k platforms.
The datasheets for the RTC devices found on the affected platforms
all confirm that the year is stored as a value in the range 0-99 and
the month is stored as a value in the range 1-12. Please refer to the
datasheets for MC146818 (Apollo), DS1643 (MVME), ICM7170 (Sun 3)
and M48T02 (Sun 3x).
Reported-by: Stan Johnson <userm57@xxxxxxxxx>
Signed-off-by: Finn Thain <fthain@xxxxxxxxxxxxxxxxxxx>
Thanks, applied and queued for v4.18.
<snip>
--- a/arch/m68k/kernel/time.c
+++ b/arch/m68k/kernel/time.c
@@ -74,17 +74,17 @@ static irqreturn_t timer_interrupt(int irq, void *dummy)
void read_persistent_clock(struct timespec *ts)
{
struct rtc_time time;
+
ts->tv_sec = 0;
ts->tv_nsec = 0;
- if (mach_hwclk) {
- mach_hwclk(0, &time);
+ if (!mach_hwclk)
+ return;
+
+ mach_hwclk(0, &time);
- if ((time.tm_year += 1900) < 1970)
- time.tm_year += 100;
Note that this change may break existing users. I'm perfectly fine with
it as doing this is generally wrong anyway and this is something I'd
like to see eliminated.
The year handling is moved into the various mach_hwclk() implementations
in the same patch (in the "<snip>" part).
- ts->tv_sec = mktime(time.tm_year, time.tm_mon, time.tm_mday,
- time.tm_hour, time.tm_min, time.tm_sec);
- }
+ ts->tv_sec = mktime(time.tm_year + 1900, time.tm_mon + 1, time.tm_mday,
+ time.tm_hour, time.tm_min, time.tm_sec);
That might explain why my Amiga spends so much time on file system checks
since I wrote the rp5c01 RTC driver...
Upon closer look, it's not, as Amiga no longer provides mach_hwclk().
So it must be due to fsck running before the rtc module is loaded?
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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