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net: phy: dp83867: add w/a for packet errors seen with short cables

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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: 2a10154abc ("net: phy: dp83867: Add TI dp83867 phy")
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Siddharth Vadapalli <s-vadapalli@ti.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Grygorii Strashko 2023-05-10 18:21:39 +05:30 committed by David S. Miller
parent f816b9829b
commit 0b01db2740
1 changed files with 21 additions and 1 deletions
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22
drivers/net/phy/dp83867.c
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@ -44,6 +44,7 @@
#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
@ -941,8 +942,27 @@ 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)