From mboxrd@z Thu Jan 1 00:00:00 1970 From: boris.brezillon@bootlin.com (Boris Brezillon) Date: Tue, 21 Aug 2018 12:43:52 +0200 Subject: [PATCH v2 06/29] mtd: Add support for reading MTD devices via the nvmem API In-Reply-To: References: <20180810080526.27207-1-brgl@bgdev.pl> <20180810080526.27207-7-brgl@bgdev.pl> <20180817182720.6a6e5e8e@bbrezillon> <20180819133106.0420df5f@tock> <20180819184609.6dcdbb9a@bbrezillon> <5b8c30b8-41e1-d59e-542b-fef6c6469ff0@linaro.org> <20180820202038.5d3dc195@bbrezillon> <20180821115639.4894c1c9@bbrezillon> Message-ID: <20180821124352.21340939@bbrezillon> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tue, 21 Aug 2018 11:11:58 +0100 Srinivas Kandagatla wrote: > On 21/08/18 10:56, Boris Brezillon wrote: > > On Tue, 21 Aug 2018 10:50:07 +0100 > > Srinivas Kandagatla wrote: > > > >> On 20/08/18 19:20, Boris Brezillon wrote: > >>> On Mon, 20 Aug 2018 11:43:34 +0100 > >>> Srinivas Kandagatla wrote: > >>> > >>>> Overall am still not able to clear visualize on how MTD bindings with > >>>> nvmem cells would look in both partition and un-partition usecases? > >>>> An example DT would be nice here!! > >>> Something along those lines: > >>> > >> This looks good to me. > >>> mtdnode { > >>> nvmem-cells { > >>> #address-cells = <1>; > >>> #size-cells = <1>; > >>> > >>> cell at 0 { > >>> reg = <0x0 0x14>; > >>> }; > >>> }; > >>> > >>> partitions { > >>> compatible = "fixed-partitions"; > >>> #address-cells = <1>; > >>> #size-cells = <1>; > >>> > >>> partition at 0 { > >>> reg = <0x0 0x20000>; > >>> > >>> nvmem-cells { > >>> #address-cells = <1>; > >>> #size-cells = <1>; > >>> > >>> cell at 0 { > >>> reg = <0x0 0x10>; > >>> }; > >>> }; > >>> }; > >>> }; > >>> }; > > >> Just curious...Is there a reason why we can't do it like this?: > >> Is this because of issue of #address-cells and #size-cells Or mtd > >> bindings always prefer subnodes? > >> > >> mtdnode { > >> reg = <0x0123000 0x40000>; > >> #address-cells = <1>; > >> #size-cells = <1>; > >> cell at 0 { > >> compatible = "nvmem-cell"; > >> reg = <0x0 0x14>; > >> }; > >> > >> partitions { > >> compatible = "fixed-partitions"; > >> #address-cells = <1>; > >> #size-cells = <1>; > >> > >> partition at 0 { > >> reg = <0x0 0x20000>; > >> cell at 0 { > >> compatible = "nvmem-cell"; > >> reg = <0x0 0x10>; > >> }; > >> }; > >> }; > >> }; > > It's because partitions were initially directly defined under the mtd > > node, so, if you have an old DT you might have something like: > > > > mtdnode { > > reg = <0x0123000 0x40000>; > > #address-cells = <1>; > > #size-cells = <1>; > > > > partition at 0 { > > reg = <0x0 0x20000>; > > ... > > }; > > ... > > }; > > > > If we use such a DT with this patch applied, the NVMEM framework will > > consider MTD partitions as nvmem cells, which is not what we want. > Yep, I agree. > TBH, I wanted to add compatible string to nvmem-cell at some point in > time and it seems more natural update too. One of the reason we > discussed this in the past was parsers. Looks like mtd can make use of this. > > We should be able to add this as an optional flag in nvmem_config to > enforce this check in case providers wanted to. > > Do you think that would help mtd nvmem case? Yes, it should work if nvmem cells are defined directly under the mtd node (or the partition they belong to). > Also I felt like nvmem-cells subnode seems to be a bit heavy! I still think grouping nvmem cells in a subnode is cleaner (just like we do for partitions), but I won't object if all parties (you, Alban and Rob) agree on this solution.