[Skiboot] [PATCH] dctl: p9 increase thread quiesce timeout

[Nicholas Piggin]

We require all instructions to be completed before a thread is
considered stopped, by the dctl interface. Long running instructions
like cache misses and CI loads may take a significant amount of time
to complete, and timeouts have been observed in stress testing.

Increase the timeout significantly, to cover this. The workbook
just says to poll, but we like to have timeouts to avoid getting
stuck in firmware.

Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
---
 core/direct-controls.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/core/direct-controls.c b/core/direct-controls.c
index ba3e4d1d3..411a1b285 100644
--- a/core/direct-controls.c
+++ b/core/direct-controls.c
@@ -263,7 +263,9 @@ static int p8_sreset_thread(struct cpu_thread *cpu)
 
 #define P9_RAS_STATUS			0x10a02
 #define P9_THREAD_QUIESCED(t)		PPC_BITMASK(0 + 8*(t), 3 + 8*(t))
-#define P9_QUIESCE_RETRIES		100
+/* Long running instructions may take time to complete. Timeout 100ms */
+#define P9_QUIESCE_POLL_INTERVAL	100
+#define P9_QUIESCE_TIMEOUT		100000
 
 #define P9_EC_DIRECT_CONTROLS		0x10a9c
 #define P9_THREAD_STOP(t)		PPC_BIT(7 + 8*(t))
@@ -306,7 +308,7 @@ static int p9_core_set_special_wakeup(struct cpu_thread *cpu)
 		return OPAL_HARDWARE;
 	}
 
-	for (i = 0; i < P9_SPWKUP_TIMEOUT/P9_SPWKUP_POLL_INTERVAL; i++) {
+	for (i = 0; i < P9_SPWKUP_TIMEOUT / P9_SPWKUP_POLL_INTERVAL; i++) {
 		if (xscom_read(chip_id, sshhyp_addr, &val)) {
 			prlog(PR_ERR, "Could not set special wakeup on %u:%u:"
 					" Unable to read PPM_SSHHYP.\n",
@@ -357,7 +359,7 @@ static int p9_core_clear_special_wakeup(struct cpu_thread *cpu)
 	}
 	time_wait_us(1);
 
-	for (i = 0; i < P9_SPWKUP_TIMEOUT/P9_SPWKUP_POLL_INTERVAL; i++) {
+	for (i = 0; i < P9_SPWKUP_TIMEOUT / P9_SPWKUP_POLL_INTERVAL; i++) {
 		if (xscom_read(chip_id, sshhyp_addr, &val)) {
 			prlog(PR_ERR, "Could not clear special wakeup on %u:%u:"
 					" Unable to read PPM_SSHHYP.\n",
@@ -392,6 +394,12 @@ static int p9_thread_quiesced(struct cpu_thread *cpu)
 		return OPAL_HARDWARE;
 	}
 
+	/*
+	 * This returns true when the thread is quiesced and all
+	 * instructions completed. For sreset this may not be necessary,
+	 * but we may want to use instruction ramming or stepping
+	 * direct controls where it is important.
+	 */
 	if ((ras_status & P9_THREAD_QUIESCED(thread_id))
 			== P9_THREAD_QUIESCED(thread_id))
 		return 1;
@@ -425,12 +433,14 @@ static int p9_stop_thread(struct cpu_thread *cpu)
 		return OPAL_HARDWARE;
 	}
 
-	for (i = 0; i < P9_QUIESCE_RETRIES; i++) {
+	for (i = 0; i < P9_QUIESCE_TIMEOUT / P9_QUIESCE_POLL_INTERVAL; i++) {
 		int rc = p9_thread_quiesced(cpu);
 		if (rc < 0)
 			break;
 		if (rc)
 			return 0;
+
+		time_wait_us(P9_QUIESCE_POLL_INTERVAL);
 	}
 
 	prlog(PR_ERR, "Could not stop thread %u:%u:%u:"
-- 
2.15.0