netdev - Re: [RFC] net: dsa: qca8k: CPU port broken with commit 5502b218e001 ("net: phy: use phy_resolve_aneg_linkmode in genphy_read

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Date:   Thu, 21 Feb 2019 01:38:55 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Michal Vokáč <michal.vokac@...ft.com>
Cc:     Vinod Koul <vkoul@...nel.org>,
        Heiner Kallweit <hkallweit1@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Florian Fainelli <f.fainelli@...il.com>, netdev@...r.kernel.org
Subject: Re: [RFC] net: dsa: qca8k: CPU port broken with commit 5502b218e001
 ("net: phy: use phy_resolve_aneg_linkmode in genphy_read_status")

On Wed, Feb 20, 2019 at 04:02:32PM +0100, Michal Vokáč wrote:
> Hi,
> 
> Another issue in a row with networking on imx6dl-yapp4 platform [1]
> that uses QCA8334 Ethernet switch.
> 
> Very recently, with Vinod and Andrew, we solved an issue with
> RGMII_ID mode by patch[2][3]. I tested those with next-20190215
> and it worked just fine.
> 
> The patch[2] was merged into next-20190220 so I tested the latest version.
> Now the cpu port does not work again. I tracked it down to this commit
> 5502b218e001 ("net: phy: use phy_resolve_aneg_linkmode in
> genphy_read_status") [4]
> 
> If I revert the offending commit, cpu port works fine. I suspect the
> problem is on the qca8k driver side but I am not really sure.
> AFAICT autonegotiation is not available on the QCA833x cpu port (MAC0).
> 
> Any ideas what may be the root cause of the problem?

Hi Michal

I would suggest taking a look at dsa_port_fixed_link_register_of().

It might be a bit more state needs initialising before calling
genphy_read_status()?

	Andrew