Re: [PATCH V2 08/14] net: ks8851: Use 16-bit writes to program MAC address

On 3/25/20 5:56 PM, Michal Kubecek wrote:

On Wed, Mar 25, 2020 at 04:05:37PM +0100, Marek Vasut wrote:

quoted

On the SPI variant of KS8851, the MAC address can be programmed with
either 8/16/32-bit writes. To make it easier to support the 16-bit
parallel option of KS8851 too, switch both the MAC address programming
and readout to 16-bit operations.

Remove ks8851_wrreg8() as it is not used anywhere anymore.

There should be no functional change.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: David S. Miller <davem@davemloft.net>
Cc: Lukas Wunner <lukas@wunner.de>
Cc: Petr Stetiar <redacted>
Cc: YueHaibing <redacted>
---
V2: Get rid of the KS_MAR(i + 1) by adjusting KS_MAR(x) macro
---

[...]

quoted

@@ -358,8 +329,12 @@ static int ks8851_write_mac_addr(struct net_device *dev)
 	 * the first write to the MAC address does not take effect.
 	 */
 	ks8851_set_powermode(ks, PMECR_PM_NORMAL);
-	for (i = 0; i < ETH_ALEN; i++)
-		ks8851_wrreg8(ks, KS_MAR(i), dev->dev_addr[i]);
+
+	for (i = 0; i < ETH_ALEN; i += 2) {
+		val = (dev->dev_addr[i] << 8) | dev->dev_addr[i + 1];
+		ks8851_wrreg16(ks, KS_MAR(i), val);
+	}
+
 	if (!netif_running(dev))
 		ks8851_set_powermode(ks, PMECR_PM_SOFTDOWN);
 

@@ -377,12 +352,16 @@ static int ks8851_write_mac_addr(struct net_device *dev)
 static void ks8851_read_mac_addr(struct net_device *dev)
 {
 	struct ks8851_net *ks = netdev_priv(dev);
+	u16 reg;
 	int i;
 
 	mutex_lock(&ks->lock);
 
-	for (i = 0; i < ETH_ALEN; i++)
-		dev->dev_addr[i] = ks8851_rdreg8(ks, KS_MAR(i));
+	for (i = 0; i < ETH_ALEN; i += 2) {
+		reg = ks8851_rdreg16(ks, KS_MAR(i));
+		dev->dev_addr[i] = reg & 0xff;
+		dev->dev_addr[i + 1] = reg >> 8;
+	}
 
 	mutex_unlock(&ks->lock);
 }

It seems my question from v1 went unnoticed and the inconsistency still
seems to be there so let me ask again: when writing, you put addr[i]
into upper part of the 16-bit value and addr[i+1] into lower but when 
reading, you do the opposite. Is it correct?

I believe so, and it works at least on the hardware I have here.
I need to wait for Lukas to verify that on KS8851 SPI edition tomorrow
(that's also why I sent out the V2, so he can test it out)