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