tree b1b62355deb4f1c962f37dcfb35175c650f79eb3
parent 4edf8ffe0c826dab2a8c418fb44bef74a6be41ed
author Nicholas Piggin <npiggin@gmail.com> 1523360972 +1000
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1525212789 -0700

rtc: opal: Fix OPAL RTC driver OPAL_BUSY loops

commit 682e6b4da5cbe8e9a53f979a58c2a9d7dc997175 upstream.

The OPAL RTC driver does not sleep in case it gets OPAL_BUSY or
OPAL_BUSY_EVENT from firmware, which causes large scheduling
latencies, up to 50 seconds have been observed here when RTC stops
responding (BMC reboot can do it).

Fix this by converting it to the standard form OPAL_BUSY loop that
sleeps.

Fixes: 628daa8d5abf ("powerpc/powernv: Add RTC and NVRAM support plus RTAS fallbacks")
Cc: stable@vger.kernel.org # v3.2+
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>