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

[Benedikt Spranger]

From: Kurt Kanzenbach <k...@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 <k...@linutronix.de>
Signed-off-by: Benedikt Spranger <b.spran...@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