Messages in this thread | | | Date | Mon, 9 Oct 2023 10:44:56 +0100 | Subject | Re: [PATCH v12 2/7] nvmem: Clarify the situation when there is no DT node available | From | Srinivas Kandagatla <> |
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On 06/10/2023 17:32, Miquel Raynal wrote: > Hi Rafał, > > rafal@milecki.pl wrote on Fri, 06 Oct 2023 13:41:52 +0200: > >> On 2023-10-05 17:59, Miquel Raynal wrote: >>> At a first look it might seem that the presence of the of_node pointer >>> in the nvmem device does not matter much, but in practice, after > looking >>> deep into the DT core, nvmem_add_cells_from_dt() will simply and always >>> return NULL if this field is not provided. As most mtd devices don't >>> populate this field (this could evolve later), it means none of their >>> children cells will be populated unless no_of_node is explicitly set to >>> false. In order to clarify the logic, let's add clear check at the >>> beginning of this helper. >> >> I'm somehow confused by above explanation and code too. I read it >> carefully 5 times but I can't see what exactly this change helps with. >> >> At first look at nvmem_add_cells_from_legacy_of() I can see it uses >> "of_node" so I don't really agree with "it might seem that the presence >> of the of_node pointer in the nvmem device does not matter much". >> >> You really don't need to look deep into DT core (actually you don't have >> to look into it at all) to understand that nvmem_add_cells_from_dt() >> will return 0 (nitpicking: not NULL) for a NULL pointer. It's all made >> of for_each_child_of_node(). Obviously it does nothing if there is >> nothing to loop over. > > That was not obvious to me as I thought it would start from /, which I > think some other function do when you don't provide a start node. > >> Given that for_each_child_of_node() is NULL-safe I think code from this >> patch is redundant. > > I didn't say it was not safe, just not explicit. > >> Later you mention "no_of_node" which I agree to be a very non-intuitive >> config option. As pointed in another thread I already sent: >> [PATCH] Revert "nvmem: add new config option" >> https://lore.kernel.org/lkml/ba3c419a-6511-480a-b5f2-6c418f9c02e7@gmail.com/t/ > > I actually wanted to find again that patch and could not get my hands on > it, but it is probably a much better fix than my other mtd patch, I > agree with you. > >> Maybe with above patch finally things will get more clear and we don't >> need this PATCH after all? > > Yes. Srinivas, what are your plans for the above patch?
for_each_child_of_node is null safe, so this patch is really not adding much value TBH.
--srini > > Thanks, > Miquèl
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