On Wed, May 04, 2022 at 10:23:16PM +0200, Rafał Miłecki wrote: > On 29.04.2022 14:48, Ansuel Smith wrote: > > This very small series comes to fix the very annyoing problem of > > partitions declared by parser at runtime NOT supporting nvmem cells > > definition. > > > > The current implementation is very generic. The idea is to provide an of > > node if defined for everyone and not strictly limit this to nvmem stuff. > > But still the actual change is done only for nvmem-cells mtd. (just to > > make sure) This can totally change by removing the compatible check. > > > > The idea here is that a user can still use these dynamic parsers > > instead of declaring a fixed-partition and also declare how nvmem-cells > > are defined for the partition. > > This live with the assumption that dynamic partition have always the > > same name and they are known. (this is the case for smem-part partition > > that would require a bootloader reflash to change and for parsers like > > cmdlinepart where the name is always the same.) > > With this assumption, it's easy to fix this problem. Just introduce a > > new partition node that will declare just these special partition. > > Mtdcore then will check if these special declaration are present and > > connect the dynamic partition with the OF node present in the dts. Nvmem > > will automagically fin the OF node and cells will be works based on the > > data provided by the parser. > > > > The initial idea was to create a special nvmem driver with a special > > compatible where a user would declare the mtd partition name and this > > driver would search it and register the nvmem cells but that became > > difficult really fast, mtd notifier system is problematic for this kind > > of stuff. So here is the better implementation. A variant of this is > > already tested on openwrt where we have devices that use cmdlinepart. > > (that current variant have defined in the dts the exact copy of > > cmdlinepart in the fixed-partition scheme and we patched the cmdlinepart > > parser to scan this fixed-partition node (that is ignored as cmdlinepart > > have priority) and connect the dynamic partition with the dts node) > > > > I provided an example of this in the documentation commit. > > In short it's needed to add to the partitions where the compatible parser > > is declared, a partition with just the label declared (instead of the reg). > > Then declare some nvmem-cells and it will all work at runtime. > > Mtdcore will check if a node with the same label is present and assign an > > OF node to the MTD. > > > > I currently tested this on my device that have smem-part and the > > gmac driver use nvmem to get the mac-address. This works correctly and > > the same address is provided. > > Thanks a lot for working on this. > > Another case (that I need this work for) is cmdline parser. Some > partitions passed by U-Boot may require extra handling and that needs to > be described in DT. I see more and more OEMs and SoC using special parser to declare partition so this is starting to become necessary. -- Ansuel
