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Date: Mon, 04 Apr 2011 16:29:04 +0200 From: Alexander Holler <holler@...oftware.de> To: linux-kernel@...r.kernel.org CC: linux-omap@...r.kernel.org Subject: rtc-twl: catch22 in 2.6.37 and 2.6.38 when clock was never set Hello, it just happened here that the rechargeable backup battery for the RTC on a TPS65950 run out off power, because of some days while the device wasn't powered. Afterwards I couldn't read or set the clock with hwclock using a kernel 2.6.37.n or 2.6.38.n. I don't have a fix, but I think I've analyzed the problem and can offer a (bad) workaround. What happens is the following: When trying to read or set the clock with hwclock, the driver (rtc-twl) starts an alarm, but the irq for the alarm will never get called. The result is that a select in hwclock times out (for both operations, read or set). Because I had this clock running before, I've got the idea to try one of those old OMAP-kernels (2.6.32-angstrom) using the same userland. And with that kernel I could set the clock. Using 2.6.37 or 2.6.38 afterwards, hwclock did function again, both read an set are working. So it looks like there is a catch22 in kernels >=2.6.37 (I haven't tested .33-.36): When the clock was never set, the alarm(-irq) doesn't work, so hwclock doesn't work, so one can't set the clock. Regards, Alexander Holler -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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