Messages in this thread | | | Date | Wed, 29 Dec 2021 23:04:51 +0100 | From | Michael Walle <> | Subject | Re: [PATCH] of: net: support NVMEM cells with MAC in text format |
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Am 2021-12-29 19:18, schrieb Jakub Kicinski: > On Wed, 29 Dec 2021 13:40:47 +0100 Michael Walle wrote: >> > Some NVMEM devices have text based cells. In such cases MAC is stored in >> > a XX:XX:XX:XX:XX:XX format. Use mac_pton() to parse such data and >> > support those NVMEM cells. This is required to support e.g. a very >> > popular U-Boot and its environment variables. >> > >> > Signed-off-by: Rafał Miłecki <rafal@milecki.pl> >> > --- >> > Please let me know if checking NVMEM cell length (6 B vs. 17 B) can be >> > considered a good enough solution. Alternatively we could use some DT >> > property to make it explicity, e.g. something like: >> > >> > ethernet@18024000 { >> > compatible = "brcm,amac"; >> > reg = <0x18024000 0x800>; >> > >> > nvmem-cells = <&mac_addr>; >> > nvmem-cell-names = "mac-address"; >> > nvmem-mac-format = "text"; >> > }; >> >> Please note, that there is also this proposal, which had such a >> conversion >> in mind: >> https://lore.kernel.org/linux-devicetree/20211228142549.1275412-1-michael@walle.cc/ >> >> With this patch, there are now two different places where a mac >> address >> format is converted. In of_get_mac_addr_nvmem() and in the imx otp >> driver. >> And both have their shortcomings and aren't really flexible. Eg. this >> one >> magically detects the format by comparing the length, but can't be >> used for >> to swap bytes (because the length is also ETH_ALEN), which apparently >> is a >> use case in the imx otp driver. And having the conversion in an nvmem >> provider device driver is still a bad thing IMHO. >> >> I'd really like to see all these kind of transformations in one place. > > FWIW offsetting from a common base address is relatively common, that's > why we have: > > /** > * eth_hw_addr_gen - Generate and assign Ethernet address to a port > * @dev: pointer to port's net_device structure > * @base_addr: base Ethernet address > * @id: offset to add to the base address > * > * Generate a MAC address using a base address and an offset and assign > it > * to a net_device. Commonly used by switch drivers which need to > compute > * addresses for all their ports. addr_assign_type is not changed. > */ > static inline void eth_hw_addr_gen(struct net_device *dev, const u8 > *base_addr, > unsigned int id)
I didn't know that. But it doesn't help me that much because it mostly used for switches, but in my case, I also have up to four network cards (enetc) on the SoC; besides a network switch (felix). But only one source for the base mac address.
-michael
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