[Skiboot] [PATCH] FSP/RTC: Fix possible FSP R/R issue in rtc write path

[Vasant Hegde]

fsp_opal_rtc_write() checks FSP status before queueing message to FSP. But if
FSP R/R starts before getting response to queued message then we will continue
to return OPAL_BUSY_EVENT to host. In some extreme condition host may
experience hang. Once FSP is back we will repost message, get response from FSP
and return OPAL_SUCCES to host.

This patch return OPAL_SUCCESS if FSP R/R happens before getting response.

Signed-off-by: Vasant Hegde <hegdevasant at linux.vnet.ibm.com>
---
Note that this patch applies on top of Pridhvi's fix [1]
[1] https://lists.ozlabs.org/pipermail/skiboot/2017-April/006870.html

-Vasant

 hw/fsp/fsp-rtc.c | 22 +++++++++++++---------
 1 file changed, 13 insertions(+), 9 deletions(-)

diff --git a/hw/fsp/fsp-rtc.c b/hw/fsp/fsp-rtc.c
index b41e295..1de22e8 100644
--- a/hw/fsp/fsp-rtc.c
+++ b/hw/fsp/fsp-rtc.c
@@ -342,7 +342,6 @@ static int64_t fsp_rtc_send_write_request(uint32_t year_month_day,
 {
 	struct fsp_msg *msg;
 	uint32_t w0, w1, w2;
-	struct tm tm;
 
 	assert(lock_held_by_me(&rtc_lock));
 	assert(rtc_write_request_state == RTC_WRITE_NO_REQUEST);
@@ -362,14 +361,7 @@ static int64_t fsp_rtc_send_write_request(uint32_t year_month_day,
 	}
 	prlog(PR_TRACE, " -> req at %p\n", msg);
 
-	if (fsp_in_rr()) {
-		datetime_to_tm(msg->data.words[0],
-			       (u64) msg->data.words[1] << 32,  &tm);
-		rtc_cache_update(&tm);
-		rtc_tod_cache_dirty = true;
-		fsp_freemsg(msg);
-		return OPAL_SUCCESS;
-	} else if (fsp_queue_msg(msg, fsp_rtc_req_complete)) {
+	if (fsp_queue_msg(msg, fsp_rtc_req_complete)) {
 		prlog(PR_TRACE, " -> queueing failed !\n");
 		fsp_freemsg(msg);
 		return OPAL_INTERNAL_ERROR;
@@ -384,6 +376,7 @@ static int64_t fsp_opal_rtc_write(uint32_t year_month_day,
 				  uint64_t hour_minute_second_millisecond)
 {
 	int rc;
+	struct tm tm;
 
 	lock(&rtc_lock);
 	if (rtc_tod_state == RTC_TOD_PERMANENT_ERROR) {
@@ -391,6 +384,17 @@ static int64_t fsp_opal_rtc_write(uint32_t year_month_day,
 		goto out;
 	}
 
+	if (fsp_in_rr()) {
+		if (rtc_write_request_state != RTC_WRITE_PENDING_REQUEST) {
+			datetime_to_tm(year_month_day,
+				       hour_minute_second_millisecond, &tm);
+			rtc_cache_update(&tm);
+			rtc_tod_cache_dirty = true;
+		}
+		rc = OPAL_SUCCESS;
+		goto out;
+	}
+
 	if (rtc_write_request_state == RTC_WRITE_NO_REQUEST) {
 		prlog(PR_TRACE, "Sending new RTC write request\n");
 		rc = fsp_rtc_send_write_request(year_month_day,
-- 
2.9.3