net: phy: micrel: Use correct skew values on KSZ9021

Commit ff7bd212cb8a ("net: phy: micrel: fix divisor value for KSZ9031
phy skew") fixed the skew value divisor for the KSZ9031, but left the
code using the same divisor for the KSZ9021, which is incorrect.

The preceding commit c16e69f702b1 ("net: phy: micrel: add documentation
for Micrel KSZ90x1 binding") added the DTS documentation for the
KSZ90x1, changing it from the equivalent file in the Linux kernel to
correctly state that for this part the skew value is set in 120ps steps,
whereas the Linux documentation and driver continue to this day to use
the incorrect value of 200 that came from the original KSZ9021 datasheet
before it was corrected in revision 1.2 (Feb 2014).

This commit sorts out the resulting confusion in a consistent way by
making the following changes:

- Update the documentation to be clear about what the skew values mean,
in the same was as for the KSZ9031.

- Update the Micrel PHY driver to select the appropriate divisor for
both parts.

- Adjust all the device trees that state skew values for KSZ9021 PHYs to
use values based on 120ps steps instead of 200ps steps. This will result
in the same values being programmed into the skew registers as the
equivalent device trees in the Linux kernel do, where it incorrectly
uses 200ps steps (since that's where all these device trees were copied
from).

Signed-off-by: James Byrne <james.byrne@origamienergy.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>

1 files changed, 10 insertions, 4 deletions

diff --git a/drivers/net/phy/micrel_ksz90x1.c b/drivers/net/phy/micrel_ksz90x1.c
index 63e7b0242b..1f8d86ab2e 100644
--- a/drivers/net/phy/micrel_ksz90x1.c
+++ b/drivers/net/phy/micrel_ksz90x1.c
@@ -33,10 +33,14 @@
 #define CTRL1000_CONFIG_MASTER		(1 << 11)
 #define CTRL1000_MANUAL_CONFIG		(1 << 12)
 
+#define KSZ9021_PS_TO_REG		120
+
 /* KSZ9031 PHY Registers */
 #define MII_KSZ9031_MMD_ACCES_CTRL	0x0d
 #define MII_KSZ9031_MMD_REG_DATA	0x0e
 
+#define KSZ9031_PS_TO_REG		60
+
 static int ksz90xx_startup(struct phy_device *phydev)
 {
 	unsigned phy_ctl;
@@ -102,11 +106,11 @@ static const struct ksz90x1_reg_field ksz9031_clk_grp[] = {
 };
 
 static int ksz90x1_of_config_group(struct phy_device *phydev,
-				   struct ksz90x1_ofcfg *ofcfg)
+				   struct ksz90x1_ofcfg *ofcfg,
+				   int ps_to_regval)
 {
 	struct udevice *dev = phydev->dev;
 	struct phy_driver *drv = phydev->drv;
-	const int ps_to_regval = 60;
 	int val[4];
 	int i, changed = 0, offset, max;
 	u16 regval = 0;
@@ -148,7 +152,8 @@ static int ksz9021_of_config(struct phy_device *phydev)
 	int i, ret = 0;
 
 	for (i = 0; i < ARRAY_SIZE(ofcfg); i++) {
-		ret = ksz90x1_of_config_group(phydev, &(ofcfg[i]));
+		ret = ksz90x1_of_config_group(phydev, &ofcfg[i],
+					      KSZ9021_PS_TO_REG);
 		if (ret)
 			return ret;
 	}
@@ -167,7 +172,8 @@ static int ksz9031_of_config(struct phy_device *phydev)
 	int i, ret = 0;
 
 	for (i = 0; i < ARRAY_SIZE(ofcfg); i++) {
-		ret = ksz90x1_of_config_group(phydev, &(ofcfg[i]));
+		ret = ksz90x1_of_config_group(phydev, &ofcfg[i],
+					      KSZ9031_PS_TO_REG);
 		if (ret)
 			return ret;
 	}