linux-kernel - Re: [PATCH net-next] net: phy: qcom: qca808x: Add .get_rate

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Message-ID: <aMgCA13MhTnG80_V@shell.armlinux.org.uk>
Date: Mon, 15 Sep 2025 13:09:39 +0100
From: "Russell King (Oracle)" <linux@...linux.org.uk>
To: Mohd Ayaan Anwar <mohd.anwar@....qualcomm.com>
Cc: andrew@...n.ch, Heiner Kallweit <hkallweit1@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	netdev@...r.kernel.org, linux-arm-msm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next] net: phy: qcom: qca808x: Add .get_rate_matching
 support

On Mon, Sep 15, 2025 at 02:25:36PM +0530, Mohd Ayaan Anwar wrote:
> [    7.937871] qcom-ethqos 23040000.ethernet: IRQ eth_wake_irq not found
> [    7.944581] qcom-ethqos 23040000.ethernet: IRQ eth_lpi not found
> [    7.953753] qcom-ethqos 23040000.ethernet: User ID: 0x20, Synopsys ID: 0x52
> [    7.960927] qcom-ethqos 23040000.ethernet:   DWMAC4/5

So we're using stmmac as the MAC.

> [    8.348697] qcom-ethqos 23040000.ethernet eth0: PHY stmmac-0:1c uses interfaces 4,23, validating 23
> [    8.358304] qcom-ethqos 23040000.ethernet eth0:  interface 23 (2500base-x) rate match none supports 6,13-14,47

This shows that the PHY supports SGMII (4) and 2500base-X (23). However,
as we only validate 2500base-X, this suggests stmmac doesn't support
switching between SGMII and 2500base-X.

> // I changed the link partner speed to 1G here:
> [   74.031182] qcom-ethqos 23040000.ethernet eth0: phy link down 2500base-x/Unknown/Unknown/none/off/nolpi
> [   74.031773] qcom-ethqos 23040000.ethernet eth0: Link is Down

As the PHY will be programmed to only advertise 2500base-T, this is
expected.

> For reference, this board is using the same MAC as [0] which works
> perfectly fine with the AQR115C PHY. I got the (wrong) idea to add
> .get_rate_matching after comparing the two PHY drivers. The MAC driver
> is stmmac/dwmac-qcom-ethqos.c

AQR115C can be configured to support rate matching.

What *exactly* is the setup with stmmac here? Do you have an external
PCS to support 2500base-X, or are you using the stmmac internal PCS?

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!