linux-kernel - [PATCH 3.12 03/88] powerpc/pseries/eeh: Handle RTAS delay requests in configure

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Date:	Thu, 14 Jul 2016 10:14:55 +0200
From:	Jiri Slaby <jslaby@...e.cz>
To:	stable@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, Russell Currey <ruscur@...sell.cc>,
	Michael Ellerman <mpe@...erman.id.au>,
	Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH 3.12 03/88] powerpc/pseries/eeh: Handle RTAS delay requests in configure_bridge

From: Russell Currey <ruscur@...sell.cc>

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

commit 871e178e0f2c4fa788f694721a10b4758d494ce1 upstream.

In the "ibm,configure-pe" and "ibm,configure-bridge" RTAS calls, the
spec states that values of 9900-9905 can be returned, indicating that
software should delay for 10^x (where x is the last digit, i.e. 990x)
milliseconds and attempt the call again. Currently, the kernel doesn't
know about this, and respecting it fixes some PCI failures when the
hypervisor is busy.

The delay is capped at 0.2 seconds.

Signed-off-by: Russell Currey <ruscur@...sell.cc>
Acked-by: Gavin Shan <gwshan@...ux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
---
 arch/powerpc/platforms/pseries/eeh_pseries.c | 51 ++++++++++++++++++++--------
 1 file changed, 36 insertions(+), 15 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/eeh_pseries.c b/arch/powerpc/platforms/pseries/eeh_pseries.c
index 74448701b636..76246a7ef10f 100644
--- a/arch/powerpc/platforms/pseries/eeh_pseries.c
+++ b/arch/powerpc/platforms/pseries/eeh_pseries.c
@@ -612,29 +612,50 @@ static int pseries_eeh_configure_bridge(struct eeh_pe *pe)
 {
 	int config_addr;
 	int ret;
+	/* Waiting 0.2s maximum before skipping configuration */
+	int max_wait = 200;
 
 	/* Figure out the PE address */
 	config_addr = pe->config_addr;
 	if (pe->addr)
 		config_addr = pe->addr;
 
-	/* Use new configure-pe function, if supported */
-	if (ibm_configure_pe != RTAS_UNKNOWN_SERVICE) {
-		ret = rtas_call(ibm_configure_pe, 3, 1, NULL,
-				config_addr, BUID_HI(pe->phb->buid),
-				BUID_LO(pe->phb->buid));
-	} else if (ibm_configure_bridge != RTAS_UNKNOWN_SERVICE) {
-		ret = rtas_call(ibm_configure_bridge, 3, 1, NULL,
-				config_addr, BUID_HI(pe->phb->buid),
-				BUID_LO(pe->phb->buid));
-	} else {
-		return -EFAULT;
-	}
+	while (max_wait > 0) {
+		/* Use new configure-pe function, if supported */
+		if (ibm_configure_pe != RTAS_UNKNOWN_SERVICE) {
+			ret = rtas_call(ibm_configure_pe, 3, 1, NULL,
+					config_addr, BUID_HI(pe->phb->buid),
+					BUID_LO(pe->phb->buid));
+		} else if (ibm_configure_bridge != RTAS_UNKNOWN_SERVICE) {
+			ret = rtas_call(ibm_configure_bridge, 3, 1, NULL,
+					config_addr, BUID_HI(pe->phb->buid),
+					BUID_LO(pe->phb->buid));
+		} else {
+			return -EFAULT;
+		}
 
-	if (ret)
-		pr_warning("%s: Unable to configure bridge PHB#%d-PE#%x (%d)\n",
-			__func__, pe->phb->global_number, pe->addr, ret);
+		if (!ret)
+			return ret;
+
+		/*
+		 * If RTAS returns a delay value that's above 100ms, cut it
+		 * down to 100ms in case firmware made a mistake.  For more
+		 * on how these delay values work see rtas_busy_delay_time
+		 */
+		if (ret > RTAS_EXTENDED_DELAY_MIN+2 &&
+		    ret <= RTAS_EXTENDED_DELAY_MAX)
+			ret = RTAS_EXTENDED_DELAY_MIN+2;
+
+		max_wait -= rtas_busy_delay_time(ret);
+
+		if (max_wait < 0)
+			break;
+
+		rtas_busy_delay(ret);
+	}
 
+	pr_warn("%s: Unable to configure bridge PHB#%d-PE#%x (%d)\n",
+		__func__, pe->phb->global_number, pe->addr, ret);
 	return ret;
 }
 
-- 
2.9.1