Am Dienstag, 3. Januar 2023, 16:51:31 CET schrieb Srinivas Kandagatla: > Hi Miquel, > > On 03/01/2023 15:39, Miquel Raynal wrote: > > Hi Srinivas, > > > > michael@xxxxxxxx wrote on Tue, 6 Dec 2022 21:07:19 +0100: > >> This is now the third attempt to fetch the MAC addresses from the VPD > >> for the Kontron sl28 boards. Previous discussions can be found here: > >> https://lore.kernel.org/lkml/20211228142549.1275412-1-michael@xxxxxxxx/ > >> > >> > >> NVMEM cells are typically added by board code or by the devicetree. But > >> as the cells get more complex, there is (valid) push back from the > >> devicetree maintainers to not put that handling in the devicetree. > >> > >> Therefore, introduce NVMEM layouts. They operate on the NVMEM device and > >> can add cells during runtime. That way it is possible to add more complex > >> cells than it is possible right now with the offset/length/bits > >> description in the device tree. For example, you can have post processing > >> for individual cells (think of endian swapping, or ethernet offset > >> handling). > >> > >> The imx-ocotp driver is the only user of the global post processing hook, > >> convert it to nvmem layouts and drop the global post pocessing hook. > >> > >> For now, the layouts are selected by the device tree. But the idea is > >> that also board files or other drivers could set a layout. Although no > >> code for that exists yet. > >> > >> Thanks to Miquel, the device tree bindings are already approved and > >> merged. > >> > >> NVMEM layouts as modules? > >> While possible in principle, it doesn't make any sense because the NVMEM > >> core can't be compiled as a module. The layouts needs to be available at > >> probe time. (That is also the reason why they get registered with > >> subsys_initcall().) So if the NVMEM core would be a module, the layouts > >> could be modules, too. > > > > I believe this series still applies even though -rc1 (and -rc2) are out > > now, may we know if you consider merging it anytime soon or if there > > are still discrepancies in the implementation you would like to > > discuss? Otherwise I would really like to see this laying in -next a > > few weeks before being sent out to Linus, just in case. > > Thanks for the work! > > Lets get some testing in -next. This causes the following errors on existing boards (imx8mq-tqma8mq- mba8mx.dtb): root@tqma8-common:~# uname -r 6.2.0-rc2-next-20230105 > OF: /soc@0: could not get #nvmem-cell-cells for /soc@0/bus@30000000/ efuse@30350000/soc-uid@4 > OF: /soc@0/bus@30800000/ethernet@30be0000: could not get #nvmem-cell-cells for /soc@0/bus@30000000/efuse@30350000/mac-address@90 These are caused because '#nvmem-cell-cells = <0>;' is not explicitly set in DT. > TI DP83867 30be0000.ethernet-1:0e: error -EINVAL: failed to get nvmem cell io_impedance_ctrl > TI DP83867: probe of 30be0000.ethernet-1:0e failed with error -22 These are caused because of_nvmem_cell_get() now returns -EINVAL instead of - ENODEV if the requested nvmem cell is not available. Best regards, Alexander
