Re: [PATCH net V2 1/1] net: phy: fix invalid phy id when probe using C22
From: Heiner Kallweit <hkallweit1@gmail.com>
Date: 2021-03-18 13:26:38
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On 18.03.2021 10:09, Wong Vee Khee wrote:
When using Clause-22 to probe for PHY devices such as the Marvell 88E2110, PHY ID with value 0 is read from the MII PHYID registers which caused the PHY framework failed to attach the Marvell PHY driver. Fixed this by adding a check of PHY ID equals to all zeroes.
I was wondering whether we have, and may break, use cases where a PHY, for whatever reason, reports PHY ID 0, but works with the genphy driver. And indeed in swphy_read_reg() we return PHY ID 0, therefore the patch may break the fixed phy. Having said that I think your patch is ok, but we need a change of the PHY ID reported by swphy_read_reg() first. At a first glance changing the PHY ID to 0x00000001 in swphy_read_reg() should be sufficient. This value shouldn't collide with any real world PHY ID.
quoted hunk ↗ jump to hunk
Fixes: ee951005e95e ("net: phy: clean up get_phy_c22_id() invalid ID handling") Cc: stable@vger.kernel.org Reviewed-by: Voon Weifeng <redacted> Signed-off-by: Wong Vee Khee <redacted> --- v2 changelog: - added fixes tag - marked for net instead of net-next --- drivers/net/phy/phy_device.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c index cc38e326405a..c12c30254c11 100644 --- a/drivers/net/phy/phy_device.c +++ b/drivers/net/phy/phy_device.c@@ -809,8 +809,8 @@ static int get_phy_c22_id(struct mii_bus *bus, int addr, u32 *phy_id) *phy_id |= phy_reg; - /* If the phy_id is mostly Fs, there is no device there */ - if ((*phy_id & 0x1fffffff) == 0x1fffffff) + /* If the phy_id is mostly Fs or all zeroes, there is no device there */ + if (((*phy_id & 0x1fffffff) == 0x1fffffff) || (*phy_id == 0)) return -ENODEV; return 0;