This is a note to let you know that I've just added the patch titled
net: phy: dp83867: add w/a for packet errors seen with short cables
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
net-phy-dp83867-add-w-a-for-packet-errors-seen-with-.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 8649533f050e1d272f171bc0dcf76f6748ece389
Author: Grygorii Strashko <grygorii.strashko@xxxxxx>
Date: Wed May 10 18:21:39 2023 +0530
net: phy: dp83867: add w/a for packet errors seen with short cables
[ Upstream commit 0b01db274028f5acd207332686ffc92ac77491ac ]
Introduce the W/A for packet errors seen with short cables (<1m) between
two DP83867 PHYs.
The W/A recommended by DM requires FFE Equalizer Configuration tuning by
writing value 0x0E81 to DSP_FFE_CFG register (0x012C), surrounded by hard
and soft resets as follows:
write_reg(0x001F, 0x8000); //hard reset
write_reg(DSP_FFE_CFG, 0x0E81);
write_reg(0x001F, 0x4000); //soft reset
Since DP83867 PHY DM says "Changing this register to 0x0E81, will not
affect Long Cable performance.", enable the W/A by default.
Fixes: 2a10154abcb7 ("net: phy: dp83867: Add TI dp83867 phy")
Signed-off-by: Grygorii Strashko <grygorii.strashko@xxxxxx>
Signed-off-by: Siddharth Vadapalli <s-vadapalli@xxxxxx>
Reviewed-by: Simon Horman <simon.horman@xxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/net/phy/dp83867.c b/drivers/net/phy/dp83867.c
index 7446d5c6c7146..14990f8462ae3 100644
--- a/drivers/net/phy/dp83867.c
+++ b/drivers/net/phy/dp83867.c
@@ -42,6 +42,7 @@
#define DP83867_STRAP_STS1 0x006E
#define DP83867_STRAP_STS2 0x006f
#define DP83867_RGMIIDCTL 0x0086
+#define DP83867_DSP_FFE_CFG 0x012c
#define DP83867_RXFCFG 0x0134
#define DP83867_RXFPMD1 0x0136
#define DP83867_RXFPMD2 0x0137
@@ -910,8 +911,27 @@ static int dp83867_phy_reset(struct phy_device *phydev)
usleep_range(10, 20);
- return phy_modify(phydev, MII_DP83867_PHYCTRL,
+ err = phy_modify(phydev, MII_DP83867_PHYCTRL,
DP83867_PHYCR_FORCE_LINK_GOOD, 0);
+ if (err < 0)
+ return err;
+
+ /* Configure the DSP Feedforward Equalizer Configuration register to
+ * improve short cable (< 1 meter) performance. This will not affect
+ * long cable performance.
+ */
+ err = phy_write_mmd(phydev, DP83867_DEVADDR, DP83867_DSP_FFE_CFG,
+ 0x0e81);
+ if (err < 0)
+ return err;
+
+ err = phy_write(phydev, DP83867_CTRL, DP83867_SW_RESTART);
+ if (err < 0)
+ return err;
+
+ usleep_range(10, 20);
+
+ return 0;
}
static void dp83867_link_change_notify(struct phy_device *phydev)
