Andy Duan <fugang.duan@xxxxxxx> [2019-05-10 08:23:58]: Hi Andy, you've probably forget to Cc some maintainers and mailing lists, so I'm adding them now to the Cc loop. This patch series should be posted against net-next tree as per netdev FAQ[0], but you've to wait little bit as net-next is currently closed for the new submissions and you would need to resend it anyway. 0. https://www.kernel.org/doc/html/latest/networking/netdev-FAQ.html > ethernet controller driver call .of_get_mac_address() to get > the mac address from devictree tree, if these properties are > not present, then try to read from nvmem. i.MX6x/7D/8MQ/8MM > platforms ethernet MAC address read from nvmem ocotp eFuses, > but it requires to swap the six bytes order. Thanks for bringing up this topic, as I would like to extend the functionality as well, but I'm still unsure how to tackle this and where, so I'll (ab)use this opportunity to bring other use cases I would like to cover in the future, so we could better understand the needs. This reverse byte order format/layout is one of a few other storage formats currently used by vendors, some other (creative) vendors are currently providing MAC addresses in NVMEMs as ASCII text in following two formats (hexdump -C /dev/mtdX): a) 0090FEC9CBE5 - MAC address stored as ASCII without colon between octets 00000090 57 2e 4c 41 4e 2e 4d 41 43 2e 41 64 64 72 65 73 |W.LAN.MAC.Addres| 000000a0 73 3d 30 30 39 30 46 45 43 39 43 42 45 35 00 48 |s=0090FEC9CBE5.H| 000000b0 57 2e 4c 41 4e 2e 32 47 2e 30 2e 4d 41 43 2e 41 |W.LAN.2G.0.MAC.A| (From https://github.com/openwrt/openwrt/pull/1448#issuecomment-442476695) b) D4:EE:07:33:6C:20 - MAC address stored as ASCII with colon between octets 00000180 66 61 63 5f 6d 61 63 20 3d 20 44 34 3a 45 45 3a |fac_mac = D4:EE:| 00000190 30 37 3a 33 33 3a 36 43 3a 32 30 0a 42 44 49 4e |07:33:6C:20.BDIN| (From https://github.com/openwrt/openwrt/pull/1906#issuecomment-483881911) > The patch set is to add property "nvmem_macaddr_swap" to swap > macaddr bytes order. so it would allow following DT construct (simplified): ð0 { nvmem-cells = <ð0_addr>; nvmem-cell-names = "mac-address"; nvmem_macaddr_swap; }; I'm not sure about the `nvmem_macaddr_swap` property name, as currently there are no other properties with underscores, so it should be probably named as `nvmem-macaddr-swap`. DT specs permits use of the underscores, but the estabilished convention is probably prefered. In order to cover all above mentioned use cases, it would make more sense to add a description of the MAC address layout to the DT and use this information to properly postprocess the NVMEM content into usable MAC address? Something like this? - nvmem-cells: phandle, reference to an nvmem node for the MAC address - nvmem-cell-names: string, should be "mac-address" if nvmem is to be used - nvmem-mac-address-layout: string, specifies MAC address storage layout. Supported values are: "binary", "binary-swapped", "ascii", "ascii-delimited". "binary" is the default. Or perhaps something like this? - nvmem-cells: phandle, reference to an nvmem node for the MAC address - nvmem-cell-names: string, should be any of the supported values. Supported values are: "mac-address", "mac-address-swapped", "mac-address-ascii", "mac-address-ascii-delimited". I'm more inclined towards the first proposed solution, as I would like to propose MAC address octet incrementation feature in the future, so it would become: - nvmem-cells: phandle, reference to an nvmem node for the MAC address - nvmem-cell-names: string, should be "mac-address" if nvmem is to be used - nvmem-mac-address-layout: string, specifies MAC address storage layout. Supported values are: "binary", "binary-swapped", "ascii", "ascii-delimited". "binary" is the default. - nvmem-mac-address-increment: number, value by which should be incremented MAC address octet, could be negative value as well. - nvmem-mac-address-increment-octet: number, valid values 0-5, default is 5. Specifies MAC address octet used for `nvmem-mac-address-increment`. What do you think? Cheers, Petr
