Re: [PATCH] pinctrl: sunxi: A523: fix voltage withstand encoding

Hi Andre,

Tested-by: Juan Manuel Lopez Carrillo <[email protected]>

I hit this exact bug on the Orange Pi 4A (T527) from the Ethernet side, so this
confirms the "reportedly Ethernet" with a concrete hardware data point.

Without the fix, GMAC1 (RGMII, YT8531 PHY) is RX-dead: the link comes up at
1Gbps but rx_packets stays 0, so DHCP never completes and the board is
unreachable. The PJ bank rail is 1.8V, but POW_MOD_SEL was left in 3.3V mode, so
the RGMII input thresholds were wrong and the MAC never saw RXC/RXD.

With your patch applied, RX comes back: the board gets a DHCP lease, and a 500 MB
transfer lands with ~365k rx_packets and rx_crc_errors = 0. So the CTL_INV
variant fixes it the right way, at the driver level.

For transparency on what I actually tested: I applied it on top of current
mainline (torvalds 248951ddc14d, v7.2-rc4 + a few). It didn't apply cleanly there
— it looks based on a newer pinctrl-sunxi tree — so I rebased one hunk (the
BIAS_VOLTAGE_PIO_POW_MODE_CTL_INV case in sunxi_pinctrl_set_io_bias_cfg()) onto
that tree; the change itself is unchanged.

FWIW I'd independently reverse-engineered the same inverted encoding (bit=1 ->
3.3V mode on the A523, vs earlier SoCs; the BSP calls it "power_mode_reverse"),
so this matches what I saw on hardware, and I'm glad it's handled generically now
instead of my board-specific DT hack.

One note from poking at this, in case it's useful for edge cases: on this board a
few banks behave specially — PF is the SD UHS 1.8/3.3V switch (best left alone),
and PB/PH take their voltage from VCCIO rather than a per-bank bit. Happy to test
those paths on hardware if useful.

Thanks,
Juan Manuel