Messages in this thread | | | Date | Sat, 23 Apr 2022 16:07:25 +0200 | From | Andrew Lunn <> | Subject | Re: [PATCH 2/2] net: dsa: mv88e6xxx: Handle single-chip-address OF property |
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On Sat, Apr 23, 2022 at 01:14:27PM +0000, Nathan Rossi wrote: > Handle the parsing and use of single chip addressing when the switch has > the single-chip-address property defined. This allows for specifying the > switch as using single chip addressing even when mdio address 0 is used > by another device on the bus. This is a feature of some switches (e.g. > the MV88E6341/MV88E6141) where the switch shares the bus only responding > to the higher 16 addresses.
Hi Nathan
I think i'm missing something in this explanation:
smi.c says:
/* The switch ADDR[4:1] configuration pins define the chip SMI device address * (ADDR[0] is always zero, thus only even SMI addresses can be strapped). * * When ADDR is all zero, the chip uses Single-chip Addressing Mode, assuming it * is the only device connected to the SMI master. In this mode it responds to * all 32 possible SMI addresses, and thus maps directly the internal devices. * * When ADDR is non-zero, the chip uses Multi-chip Addressing Mode, allowing * multiple devices to share the SMI interface. In this mode it responds to only * 2 registers, used to indirectly access the internal SMI devices. * * Some chips use a different scheme: Only the ADDR4 pin is used for * configuration, and the device responds to 16 of the 32 SMI * addresses, allowing two to coexist on the same SMI interface. */
So if ADDR = 0, it takes up the whole bus. And in this case reg = 0. If ADDR != 0, it is in multi chip mode, and DT reg = ADDR.
int mv88e6xxx_smi_init(struct mv88e6xxx_chip *chip, struct mii_bus *bus, int sw_addr) { if (chip->info->dual_chip) chip->smi_ops = &mv88e6xxx_smi_dual_direct_ops; else if (sw_addr == 0) chip->smi_ops = &mv88e6xxx_smi_direct_ops; else if (chip->info->multi_chip) chip->smi_ops = &mv88e6xxx_smi_indirect_ops; else return -EINVAL;
This seems to implement what is above. smi_direct_ops == whole bus, smi_indirect_ops == multi-chip mode.
In what situation do you see this not working? What device are you using, what does you DT look like, and what at the ADDR value?
Thanks Andrew
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