Re: [PATCH] ARM: dts: imx6dl-yapp4: Use correct pseudo PHY address for the switch

[Christian Lamparter <chunkeey@gmail.com>]

On Wednesday, March 20, 2019 12:09:05 PM CET Michal Vokáč wrote:
> The switch is accessible through pseudo PHY which is located at 0x10.

from what I know the switch@0 came from John' original qca8k submission patch
<https://lore.kernel.org/patchwork/patch/715974/> (this is v1! not the later
version)

In this version, the qca8k_sw_probe() function used read the MII_PHYID1 and 2
from the PHY0 in order to identify the switch (much like ar8216.c / ar8327.c
switchdev does):

|	/* sw_addr is irrelevant as the switch occupies the MDIO bus from
|	 * addresses 0 to 4 (PHYs) and 16-23 (for MDIO 32bits protocol). So
|	 * we'll probe address 0 to see if we see the right switch family.
|	 */
|	phy_id = mdiobus_read(mdiodev->bus, 0, MII_PHYSID1) << 16;
|	phy_id |= mdiobus_read(mdiodev->bus, 0, MII_PHYSID2);
|
|	switch (phy_id) {
|	case PHY_ID_QCA8337:
|		break;
|	default:
|		return -ENODEV;
|	}

However, this code was changed in v2. Probably because if the PHY is put in
isolation and powered down the MII_PHYID1 and 2 will read "0xffff". So the
discovery would no longer worked on systems that purposely disable the switch
during the bootloader-handoff procedure (like the Meraki MX60).
 
> Signed-off-by: Michal Vokáč <michal.vokac@ysoft.com>
> ---
>  arch/arm/boot/dts/imx6dl-yapp4-common.dtsi | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm/boot/dts/imx6dl-yapp4-common.dtsi b/arch/arm/boot/dts/imx6dl-yapp4-common.dtsi
> index 091d829f6b05..e8d800fec637 100644
> --- a/arch/arm/boot/dts/imx6dl-yapp4-common.dtsi
> +++ b/arch/arm/boot/dts/imx6dl-yapp4-common.dtsi
> @@ -114,9 +114,9 @@
>  			reg = <2>;
>  		};
>  
> -		switch@0 {
> +		switch@10 {
>  			compatible = "qca,qca8334";
> -			reg = <0>;
> +			reg = <10>;
>  
>  			switch_ports: ports {
>  				#address-cells = <1>;
>