Re: powerpc: use time64_t in read_persistent_clock

On Thu, Jun 14, 2018 at 9:03 PM, Mathieu Malaterre [off-list ref] wrote:

On Thu, Jun 14, 2018 at 1:46 PM Arnd Bergmann [off-list ref] wrote:

quoted

On Wed, Jun 13, 2018 at 10:24 PM, Mathieu Malaterre [off-list ref] wrote:

quoted

Can you confirm that this patch addresses your problem?

Yes !

Before:
[    5.986710] rtc-generic rtc-generic: hctosys: unable to read the
hardware clock

After:
[    5.579611] rtc-generic rtc-generic: setting system clock to
2018-06-14 18:57:00 UTC (1529002620)

So for the above:

Tested-by: Mathieu Malaterre <redacted>

Thanks a lot!

quoted

--- a/arch/powerpc/platforms/powermac/time.c
+++ b/arch/powerpc/platforms/powermac/time.c

@@ -88,7 +88,7 @@ long __init pmac_time_init(void)
 static time64_t cuda_get_time(void)
 {
        struct adb_request req;
-       time64_t now;
+       u32 now;

        if (cuda_request(&req, NULL, 2, CUDA_PACKET, CUDA_GET_TIME) < 0)
                return 0;

@@ -132,7 +132,7 @@ static int cuda_set_rtc_time(struct rtc_time *tm)
 static time64_t pmu_get_time(void)
 {
        struct adb_request req;
-       time64_t now;
+       u32 now;

        if (pmu_request(&req, NULL, 1, PMU_READ_RTC) < 0)
                return 0;

On the upside, this would possibly extend the life of some machines
by another 66 years, on the downside it might cause issues when
an empty RTC battery causes the initial system time to be
above the 32-bit TIME_T_MAX (instead of going back to 1904).

I would submit the first patch and add the above as comment. I doubt
anyone would still have a running system by then.

I was about to send a similar patch to the first one for m68k macs, which have
basically the same code. My patch had the same bug, so I'm glad I had
not sent it yet, but I also noticed that I made the opposite decision on m68k
as that code had already been using 'unsigned long' in the conversion (but
then of course would wrap it during the conversion to 'time_t). I've picked
the same approach for both now, using the 1904..2040 range.

       Arnd