[PATCH] icplus: mdio_write(), remove unnecessary for loop

[PATCH] icplus: mdio_write(), remove unnecessary for loop

[Patrick Kelle]

At this point the variable j is always set to 7 and the code within
the loop has to run only once anyway.

Signed-off-by: Patrick Kelle <patrick.kelle81@gmail.com>
---
 drivers/net/ethernet/icplus/ipg.c |   12 +++++-------
 1 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/icplus/ipg.c b/drivers/net/ethernet/icplus/ipg.c
index 8fd80a0..a65d747 100644
--- a/drivers/net/ethernet/icplus/ipg.c
+++ b/drivers/net/ethernet/icplus/ipg.c
@@ -371,15 +371,13 @@ static void mdio_write(struct net_device *dev, int phy_id, int phy_reg, int val)
 	}
 
 	/* The last cycle is a tri-state, so read from the PHY. */
-	for (j = 7; j < 8; j++) {
-		for (i = 0; i < p[j].len; i++) {
-			ipg_write_phy_ctl(ioaddr, IPG_PC_MGMTCLK_LO | polarity);
+	for (i = 0; i < p[j].len; i++) {
+		ipg_write_phy_ctl(ioaddr, IPG_PC_MGMTCLK_LO | polarity);
 
-			p[j].field |= ((ipg_r8(PHY_CTRL) &
-				IPG_PC_MGMTDATA) >> 1) << (p[j].len - 1 - i);
+		p[j].field |= ((ipg_r8(PHY_CTRL) &
+			IPG_PC_MGMTDATA) >> 1) << (p[j].len - 1 - i);
 
-			ipg_write_phy_ctl(ioaddr, IPG_PC_MGMTCLK_HI | polarity);
-		}
+		ipg_write_phy_ctl(ioaddr, IPG_PC_MGMTCLK_HI | polarity);
 	}
 }
 
-- 
1.7.7.1

Re: [PATCH] icplus: mdio_write(), remove unnecessary for loop

[David Miller]

From: Patrick Kelle <patrick.kelle81@gmail.com>
Date: Thu, 24 Nov 2011 16:39:05 +0100

> At this point the variable j is always set to 7 and the code within
> the loop has to run only once anyway.
> 
> Signed-off-by: Patrick Kelle <patrick.kelle81@gmail.com>

You can simply this even further since p[7] is what is used here,
and this means len is one, the inner loop therefore executes only
once, and the p[7].field value is not used (it's zero in the table)
and the write to it is completely thrown away.

It all reduces to something like:

	ipg_write_phy_ctl(ioaddr, IPG_PC_MGMTCLK_LO | polarity);
	ipg_r8(PHY_CTRL);
	ipg_write_phy_ctl(ioaddr, IPG_PC_MGMTCLK_HI | polarity);

Which is just asserting the management clock low, then high, and
doing a PHY_CTRL read in between to force the write out, the read
data is not used at all.