From a2a8b263ebff901c789517908a779f54fad3f2d0 Mon Sep 17 00:00:00 2001 From: Nicholas Piggin Date: Tue, 10 Apr 2018 21:49:32 +1000 Subject: 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 Acked-by: Alexandre Belloni Signed-off-by: Michael Ellerman Signed-off-by: Greg Kroah-Hartman --- drivers/rtc/rtc-opal.c | 37 +++++++++++++++++++++++-------------- 1 file changed, 23 insertions(+), 14 deletions(-) (limited to 'drivers/rtc') diff --git a/drivers/rtc/rtc-opal.c b/drivers/rtc/rtc-opal.c index aa53fceaa5e0..180ec1f8c917 100644 --- a/drivers/rtc/rtc-opal.c +++ b/drivers/rtc/rtc-opal.c @@ -57,7 +57,7 @@ static void tm_to_opal(struct rtc_time *tm, u32 *y_m_d, u64 *h_m_s_ms) static int opal_get_rtc_time(struct device *dev, struct rtc_time *tm) { - long rc = OPAL_BUSY; + s64 rc = OPAL_BUSY; int retries = 10; u32 y_m_d; u64 h_m_s_ms; @@ -66,13 +66,17 @@ static int opal_get_rtc_time(struct device *dev, struct rtc_time *tm) while (rc == OPAL_BUSY || rc == OPAL_BUSY_EVENT) { rc = opal_rtc_read(&__y_m_d, &__h_m_s_ms); - if (rc == OPAL_BUSY_EVENT) + if (rc == OPAL_BUSY_EVENT) { + msleep(OPAL_BUSY_DELAY_MS); opal_poll_events(NULL); - else if (retries-- && (rc == OPAL_HARDWARE - || rc == OPAL_INTERNAL_ERROR)) - msleep(10); - else if (rc != OPAL_BUSY && rc != OPAL_BUSY_EVENT) - break; + } else if (rc == OPAL_BUSY) { + msleep(OPAL_BUSY_DELAY_MS); + } else if (rc == OPAL_HARDWARE || rc == OPAL_INTERNAL_ERROR) { + if (retries--) { + msleep(10); /* Wait 10ms before retry */ + rc = OPAL_BUSY; /* go around again */ + } + } } if (rc != OPAL_SUCCESS) @@ -87,21 +91,26 @@ static int opal_get_rtc_time(struct device *dev, struct rtc_time *tm) static int opal_set_rtc_time(struct device *dev, struct rtc_time *tm) { - long rc = OPAL_BUSY; + s64 rc = OPAL_BUSY; int retries = 10; u32 y_m_d = 0; u64 h_m_s_ms = 0; tm_to_opal(tm, &y_m_d, &h_m_s_ms); + while (rc == OPAL_BUSY || rc == OPAL_BUSY_EVENT) { rc = opal_rtc_write(y_m_d, h_m_s_ms); - if (rc == OPAL_BUSY_EVENT) + if (rc == OPAL_BUSY_EVENT) { + msleep(OPAL_BUSY_DELAY_MS); opal_poll_events(NULL); - else if (retries-- && (rc == OPAL_HARDWARE - || rc == OPAL_INTERNAL_ERROR)) - msleep(10); - else if (rc != OPAL_BUSY && rc != OPAL_BUSY_EVENT) - break; + } else if (rc == OPAL_BUSY) { + msleep(OPAL_BUSY_DELAY_MS); + } else if (rc == OPAL_HARDWARE || rc == OPAL_INTERNAL_ERROR) { + if (retries--) { + msleep(10); /* Wait 10ms before retry */ + rc = OPAL_BUSY; /* go around again */ + } + } } return rc == OPAL_SUCCESS ? 0 : -EIO; -- cgit v1.2.3