net: mdio: aspeed: add dummy read to avoid read-after-write issue

Browse source

The Aspeed MDIO controller may return incorrect data when a read operation
follows immediately after a write. Due to a controller bug, the subsequent
read can latch stale data, causing the polling logic to terminate earlier
than expected.

To work around this hardware issue, insert a dummy read after each write
operation. This ensures that the next actual read returns the correct
data and prevents premature polling exit.

This workaround has been verified to stabilize MDIO transactions on
affected Aspeed platforms.

Fixes: f160e99462 ("net: phy: Add mdio-aspeed")
Signed-off-by: Jacky Chou <jacky_chou@aspeedtech.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/20251211-aspeed_mdio_add_dummy_read-v3-1-382868869004@aspeedtech.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

...

This commit is contained in:

Jacky Chou 2025-12-11 14:24:58 +08:00 • committed by Paolo Abeni

parent bf4172bd87

commit d1a1a4bade

1 changed files with 7 additions and 0 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

7

drivers/net/mdio/mdio-aspeed.c

View file