Hello, alexander.stein@xxxxxxxxxxxxxxx wrote on Thu, 05 Jan 2023 12:04:52 +0100: > 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. Should we just assume #nvmem-cell-cells = <0> by default? I guess it's a safe assumption. Thanks, Miquèl
