netdev - Marvell 88E1512 PHY LED2 mode mismatch with Elkhartlake pin mode

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Message-ID: <3f6a37ab-c346-b53c-426c-133aa1ce76d7@kontron.com>
Date:   Tue, 19 Jul 2022 18:36:20 +0200
From:   Gilles BULOZ <gilles.buloz@...tron.com>
To:     netdev@...r.kernel.org
Subject: Marvell 88E1512 PHY LED2 mode mismatch with Elkhartlake pin mode

Dear developers,

On a custom Elkhartlake board based on the Intel CRB, it turns out I have the 88E1512 PHY configured in polled mode ("intel-eth-pci 
0000:00:1e.4 eno1: PHY [stmmac-1:01] driver [Marvell 88E1510] (irq=POLL)" in dmesg) and the LED2/INT# pin is configured in LED2 mode 
by marvell_config_led() in drivers/net/phy/marvell.c (MII_88E1510_PHY_LED_DEF written to MII_PHY_LED_CTRL). This pin is connected as 
on the CRB to an Elkhartlake pin for a PHY interrupt but for some reason the interrupt is enabled on the Elkhartlake.
So when I shutdown the system (S5), any activity on link makes LED2/INT# toggle and power the system back on.

I tried to force  phydev->dev_flag to use MII_88E1510_PHY_LED0_LINK_LED1_ACTIVE instead of MII_88E1510_PHY_LED_DEF but I've been 
unable to find how to force this flag. And I discovered that the value of MII_88E1510_PHY_LED0_LINK_LED1_ACTIVE = 0x1040 is not OK 
for me because LED2 is set to "link status" so if I use this value the system is back "on" on link change (better than on activity 
but still not OK).

As a final workaround I've patched drivers/net/phy/marvell.c at marvell_config_led() to have "LED0=link LED1=activity LED2=off" by 
writing 0x1840 to MII_PHY_LED_CTRL, but I know this is a ugly workaround.

So I'm wondering if PHY "irq=POLL" is the expected operating mode ?
In this case what should disable the interrupt on the Elkhartlake pin ?
Is wake on Lan supported if PHY is set to "irq=POLL" ?

Thanks for tips.