[[PATCH net-next] 0/2] Convert mdio wait function to use readx_poll_timeout()

[[PATCH net-next] 0/2] Convert mdio wait function to use readx_poll_timeout()

[Benedikt Spranger]

Hi,

On loaded systems with a preemptible kernel both functions
axienet_mdio_wait_until_ready() and xemaclite_mdio_wait() may report a
false positive error return.
Convert both functions to use readx_poll_timeout() to handle the
situation in a safe manner.

Regards
    Benedikt Spranger

Kurt Kanzenbach (2):
  net: axienet: use readx_poll_timeout() in mdio wait function
  net: xilinx_emaclite: use readx_poll_timeout() in mdio wait function

 drivers/net/ethernet/xilinx/xilinx_axienet.h     |  5 +++++
 .../net/ethernet/xilinx/xilinx_axienet_mdio.c    | 16 ++++++----------
 drivers/net/ethernet/xilinx/xilinx_emaclite.c    | 16 ++++++----------
 3 files changed, 17 insertions(+), 20 deletions(-)

-- 
2.20.1

[[PATCH net-next] 1/2] net: axienet: use readx_poll_timeout() in mdio wait function

[Benedikt Spranger]

From: Kurt Kanzenbach <kurt@linutronix.de>

On loaded systems with a preemptible kernel the mdio_wait() function may
report an error while everything is working fine:

axienet_mdio_wait_until_ready():
  axienet_ior() -> chip not ready
  --> interrupt here (other work for some time / chip become ready)
  if (time_before_eq(end, jiffies))
    --> false positive error report

Replace the current code with readx_poll_timeout() which take care
of the situation.

Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de>
Signed-off-by: Benedikt Spranger <b.spranger@linutronix.de>
---
 drivers/net/ethernet/xilinx/xilinx_axienet.h     |  5 +++++
 .../net/ethernet/xilinx/xilinx_axienet_mdio.c    | 16 ++++++----------
 2 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet.h b/drivers/net/ethernet/xilinx/xilinx_axienet.h
index c337400485da..011adae32b89 100644
--- a/drivers/net/ethernet/xilinx/xilinx_axienet.h
+++ b/drivers/net/ethernet/xilinx/xilinx_axienet.h
@@ -484,6 +484,11 @@ static inline u32 axienet_ior(struct axienet_local *lp, off_t offset)
 	return in_be32(lp->regs + offset);
 }
 
+static inline u32 axinet_ior_read_mcr(struct axienet_local *lp)
+{
+	return axienet_ior(lp, XAE_MDIO_MCR_OFFSET);
+}
+
 /**
  * axienet_iow - Memory mapped Axi Ethernet register write
  * @lp:         Pointer to axienet local structure
diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_mdio.c b/drivers/net/ethernet/xilinx/xilinx_axienet_mdio.c
index 757a3b37ae8a..704babdbc8a2 100644
--- a/drivers/net/ethernet/xilinx/xilinx_axienet_mdio.c
+++ b/drivers/net/ethernet/xilinx/xilinx_axienet_mdio.c
@@ -11,6 +11,7 @@
 #include <linux/of_address.h>
 #include <linux/of_mdio.h>
 #include <linux/jiffies.h>
+#include <linux/iopoll.h>
 
 #include "xilinx_axienet.h"
 
@@ -20,16 +21,11 @@
 /* Wait till MDIO interface is ready to accept a new transaction.*/
 int axienet_mdio_wait_until_ready(struct axienet_local *lp)
 {
-	unsigned long end = jiffies + 2;
-	while (!(axienet_ior(lp, XAE_MDIO_MCR_OFFSET) &
-		 XAE_MDIO_MCR_READY_MASK)) {
-		if (time_before_eq(end, jiffies)) {
-			WARN_ON(1);
-			return -ETIMEDOUT;
-		}
-		udelay(1);
-	}
-	return 0;
+	u32 val;
+
+	return readx_poll_timeout(axinet_ior_read_mcr, lp,
+				  val, val & XAE_MDIO_MCR_READY_MASK,
+				  1, 20000);
 }
 
 /**
-- 
2.20.1

[[PATCH net-next] 2/2] net: xilinx_emaclite: use readx_poll_timeout() in mdio wait function

[Benedikt Spranger]

From: Kurt Kanzenbach <kurt@linutronix.de>

On loaded systems with a preemptible kernel the mdio_wait() function may
report an error while everything is working fine:

xemaclite_mdio_wait():
  xemaclite_readl() -> chip not ready
  --> interrupt here (other work for some time / chip become ready)
  if (time_before_eq(end, jiffies))
    --> false positive error report

Replace the current code with readx_poll_timeout() which takes care
of the situation.

Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de>
Signed-off-by: Benedikt Spranger <b.spranger@linutronix.de>
---
 drivers/net/ethernet/xilinx/xilinx_emaclite.c | 16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/drivers/net/ethernet/xilinx/xilinx_emaclite.c b/drivers/net/ethernet/xilinx/xilinx_emaclite.c
index 6886270da695..c409bab63bd3 100644
--- a/drivers/net/ethernet/xilinx/xilinx_emaclite.c
+++ b/drivers/net/ethernet/xilinx/xilinx_emaclite.c
@@ -27,6 +27,7 @@
 #include <linux/of_net.h>
 #include <linux/phy.h>
 #include <linux/interrupt.h>
+#include <linux/iopoll.h>
 
 #define DRIVER_NAME "xilinx_emaclite"
 
@@ -714,20 +715,15 @@ static irqreturn_t xemaclite_interrupt(int irq, void *dev_id)
 
 static int xemaclite_mdio_wait(struct net_local *lp)
 {
-	unsigned long end = jiffies + 2;
+	u32 val;
 
 	/* wait for the MDIO interface to not be busy or timeout
 	 * after some time.
 	 */
-	while (xemaclite_readl(lp->base_addr + XEL_MDIOCTRL_OFFSET) &
-			XEL_MDIOCTRL_MDIOSTS_MASK) {
-		if (time_before_eq(end, jiffies)) {
-			WARN_ON(1);
-			return -ETIMEDOUT;
-		}
-		msleep(1);
-	}
-	return 0;
+	return readx_poll_timeout(xemaclite_readl,
+				  lp->base_addr + XEL_MDIOCTRL_OFFSET,
+				  val, !(val & XEL_MDIOCTRL_MDIOSTS_MASK),
+				  1000, 20000);
 }
 
 /**
-- 
2.20.1

Re: [[PATCH net-next] 0/2] Convert mdio wait function to use readx_poll_timeout()

[David Miller]

From: Benedikt Spranger <b.spranger@linutronix.de>
Date: Sun, 19 May 2019 19:59:35 +0200

> On loaded systems with a preemptible kernel both functions
> axienet_mdio_wait_until_ready() and xemaclite_mdio_wait() may report a
> false positive error return.
> Convert both functions to use readx_poll_timeout() to handle the
> situation in a safe manner.

Series applied, thank you.