From 39869587dac09c9e738960ccdf01e1dc62a906f7 Mon Sep 17 00:00:00 2001 From: Phil Elwell Date: Mon, 29 Oct 2018 14:45:45 +0000 Subject: [PATCH] Revert "rtc: pcf8523: properly handle oscillator stop bit" This reverts commit ede44c908d44b166a5b6bd7caacd105c2ff5a70f. See: https://github.com/raspberrypi/firmware/issues/1065 Signed-off-by: Phil Elwell --- drivers/rtc/rtc-pcf8523.c | 24 ++++++++++++++++++++++-- 1 file changed, 22 insertions(+), 2 deletions(-) --- a/drivers/rtc/rtc-pcf8523.c +++ b/drivers/rtc/rtc-pcf8523.c @@ -242,8 +242,28 @@ static int pcf8523_rtc_read_time(struct if (err < 0) return err; - if (regs[0] & PCF8523_SECONDS_OS) - return -EINVAL; + if (regs[0] & PCF8523_SECONDS_OS) { + /* + * If the oscillator was stopped, try to clear the flag. Upon + * power-up the flag is always set, but if we cannot clear it + * the oscillator isn't running properly for some reason. The + * sensible thing therefore is to return an error, signalling + * that the clock cannot be assumed to be correct. + */ + + regs[0] &= ~PCF8523_SECONDS_OS; + + err = pcf8523_write(client, PCF8523_REG_SECONDS, regs[0]); + if (err < 0) + return err; + + err = pcf8523_read(client, PCF8523_REG_SECONDS, ®s[0]); + if (err < 0) + return err; + + if (regs[0] & PCF8523_SECONDS_OS) + return -EAGAIN; + } tm->tm_sec = bcd2bin(regs[0] & 0x7f); tm->tm_min = bcd2bin(regs[1] & 0x7f);