[PATCH net v2 4/5] net: dsa: vsc73xx: allow phy resetting

Pawel Dembicki
2024-08-05T21:11:24Z

Resetting the VSC73xx PHY was problematic because the MDIO bus, without
a busy check, read and wrote incorrect register values.

My investigation indicates that resetting the PHY only triggers changes
in configuration. However, improper register values written earlier
were only exposed after a soft reset.

The reset itself wasn't the issue; rather, the problem stemmed from
incorrect read and write operations.

A 'soft_reset' can now proceed normally. There are no reasons to keep
the VSC73xx from being reset.

This commit removes the reset blockade in the 'vsc73xx_phy_write'
function.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Signed-off-by: Pawel Dembicki <paweldembicki@gmail.com>
---
v2:
- improved commit description

This patch came from net-next series[0].
Changes since net-next:
- rebased to netdev/main only

[0] https://patchwork.kernel.org/project/netdevbpf/patch/20240729210615.279952-6-paweldembicki@gmail.com/
---
drivers/net/dsa/vitesse-vsc73xx-core.c | 11 -----------
1 file changed, 11 deletions(-)

diff --git a/drivers/net/dsa/vitesse-vsc73xx-core.c b/drivers/net/dsa/vitesse-vsc73xx-core.c
index a9378e0512d8..ac02927a153b 100644
--- a/drivers/net/dsa/vitesse-vsc73xx-core.c
+++ b/drivers/net/dsa/vitesse-vsc73xx-core.c
@@ -599,17 +599,6 @@ static int vsc73xx_phy_write(struct dsa_switch *ds, int phy, int regnum,
if (ret)
return ret;

- /* It was found through tedious experiments that this router
- * chip really hates to have it's PHYs reset. They
- * never recover if that happens: autonegotiation stops
- * working after a reset. Just filter out this command.
- * (Resetting the whole chip is OK.)
- */
- if (regnum == 0 && (val & BIT(15))) {
- dev_info(vsc->dev, "reset PHY - disallowed\n");
- return 0;
- }
-
cmd = (phy << 21) | (regnum << 16) | val;
ret = vsc73xx_write(vsc, VSC73XX_BLOCK_MII, 0, 1, cmd);
if (ret)
--
2.34.1