Hi Maciej, On Wed, May 13, 2015 at 07:03:51PM +0100, Maciej W. Rozycki wrote: > On Wed, 13 May 2015, James Hogan wrote: > > > On Malta, the RTC is forced into binary coded decimal (BCD) mode during > > init, even if the bootloader put it into binary mode (as YAMON does). > > This can result in the RTC seconds being an invalid BCD (e.g. > > 0x1a..0x1f) for up to 6 seconds. > > Sigh. No sooner I had fixed the breakage (with 636221b8 and a fat > comment) it got put back (with a87ea88d). Even though it's easily > spotted as it breaks the system time (all the fields, including the date > too, not only the seconds!) across a reboot due to YAMON eagerly > switching the mode back. And that'd be the first item I'd check when > validating a change touching the RTC. Indeed, a quick bit of experimentation confirms a discrepancy before this patch is applied before YAMON's "date" command and the RTC clock as read by Linux (with year, day of month, hour & minute all going 22 -> 16 (22 == 0x16), and presumably different rates of time depending on which mode its in. After this patch it appears to work again as it should. > Is there an actual need to reinitialise the RTC at all? The RTC > registers are readable, so the current configuration can be obtained, > the RTC driver copes with any valid arrangement, so can any other code > using the clock as a reference. > > YAMON OTOH is not as flexible, its clock management commands expect the > format the monitor itself set the chip to, so I think the kernel has to > respect that (just as it doesn't randomly flip bits in the RTC on x86 > PCs for example). > > So unless proven otherwise I'll ask for `init_rtc' to be dropped > altogether I suspect it comes down to what U-Boot does with RTC (possibly very little), but I'll leave that to you and Paul to discuss. > and any changes required made to `estimate_frequencies' > instead. Which I believe you already did with 2/2. As long as the mode doesn't get changed, my change to estimate_frequencies() should be happy enough. Before patch 2/2 it only reads UIP flag to try to time a single second, so it shouldn't have cared about such details as the RTC mode. Cheers James
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