commit 79206c04a9269f87fd943713db70fbc53ec05ed3
author Vladimir Zapolskiy <vz@mleia.com> Sun Dec 27 05:12:24 2015 +0200
committer Tom Rini <trini@konsulko.com> Wed Jan 13 21:05:25 2016 -0500
tree ac62bc47dc5bca941ec4e8bb6568596ae902755e
parent 5c58e3a71cfa1b739b1f322fbe996fa09da33b2d

net: lpc32xx: fix ignored MDIO busy wait status on read

The change fixes PHY write operation, which incorrectly waits for
released busy state before issuing a write operation, this breaks
sequential write/read operation logic, because read operation
starts immediately on request and it completes, when busy state is
gone.

Instead of adding the second preceding busy state check to read
function, do busy state release check after issuing a write operation,
this method of operation is also recommended by the LPC32xx User's
Manual, see MII Mgmt Indicators Register notes:

  For PHY Write if scan is not used:
  1. Write 0 to MCMD
  2. Write PHY address and register address to MADR
  3. Write data to MWTD
  4. Wait for busy bit to be cleared in MIND

Reported-by: Alexandre Messier <amessier@tycoint.com>
Signed-off-by: Vladimir Zapolskiy <vz@mleia.com>
Tested-by: Alexandre Messier <amessier@tycoint.com>

drivers/net/lpc32xx_eth.c

diff --git a/drivers/net/lpc32xx_eth.c b/drivers/net/lpc32xx_eth.c
index e76e9bc..3ba5b4b 100644
--- a/drivers/net/lpc32xx_eth.c
+++ b/drivers/net/lpc32xx_eth.c
@@ -304,6 +304,13 @@
 		return -EFAULT;
 	}
 
+	/* write the phy and reg addressse into the MII address reg */
+	writel((phy_adr << MADR_PHY_OFFSET) | (reg_ofs << MADR_REG_OFFSET),
+	       &regs->madr);
+
+	/* write data to the MII write register */
+	writel(data, &regs->mwtd);
+
 	/* wait till the MII is not busy */
 	timeout = MII_TIMEOUT;
 	do {
@@ -319,13 +326,6 @@
 		return -EFAULT;
 	}
 
-	/* write the phy and reg addressse into the MII address reg */
-	writel((phy_adr << MADR_PHY_OFFSET) | (reg_ofs << MADR_REG_OFFSET),
-	       &regs->madr);
-
-	/* write data to the MII write register */
-	writel(data, &regs->mwtd);
-
 	/*debug("%s:(adr %d, off %d) <= %04x\n", __func__, phy_adr,
 		reg_ofs, data);*/