Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx> [2019-05-14 16:13:22]:
> On 13/05/2019 12:16, Petr Štetiar wrote:
> > Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx> [2019-05-13 11:06:48]:
> >
> > > On 13/05/2019 10:07, Petr Štetiar wrote:
> > > > Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx> [2019-05-13 09:25:55]:
> > > >
> > > > > My initial idea was to add compatible strings to the cell so that most of
> > > > > the encoding information can be derived from it. For example if the encoding
> > > > > representing in your example is pretty standard or vendor specific we could
> > > > > just do with a simple compatible like below:
> > > >
> > > > that vendor/compatible list would be quite long[1], there are hundreds of
> > >
> > > You are right just vendor list could be very long, but I was hoping that the
> > > post-processing would fall in some categories which can be used in
> > > compatible string.
> > >
> > > Irrespective of which we need to have some sort of compatible string to
> > > enable nvmem core to know that there is some form of post processing to be
> > > done on the cells!. Without which there is a danger of continuing to adding
> > > new properties to the cell bindings which have no relation to each other.
> >
> > makes sense, so something like this would be acceptable?
> >
> > eth1_addr: eth-mac-addr@18a {
> > /* or rather linux,nvmem-post-process ? */
> > compatible = "openwrt,nvmem-post-process";
>
> I don't think this would be a correct compatible string to use here.
> Before we decide on naming, I would like to understand bit more on what are
> the other possible forms of storing mac address,
> Here is what I found,
>
> Type 1: Octets in ASCII without delimiters. (Swapped/non-Swapped)
> Type 2: Octets in ASCII with delimiters like (":", ",", ".", "-"... so on)
> (Swapped/non-Swapped)
> Type 3: Is the one which stores mac address in Type1/2 but this has to be
> incremented to be used on other instances of eth.
>
> Did I miss anything?
Type 4: Octets as bytes/u8, swapped/non-swapped
Currently just type4-non-swapped is supported. Support for type4-swapped was
goal of this patch series.
I've simply tried to avoid using mac-address for the compatible as this
provider could be reused by other potential nvmem consumers. The question is,
how much abstracted it should be then.
> My suggestion for type1 and type2 would be something like this, as long as
> its okay with DT maintainers
>
> eth1_addr: eth-mac-addr@18a {
> compatible = "ascii-mac-address";
> reg = <0x18a 2>, <0x192 2>, <0x196 2>, <0x200 2>, <0x304 2>, <0x306 2>;
> swap-mac-address;
> delimiter = ":";
> };
with this reg array, you don't need the delimiter property anymore, do you?
> For type 3:
>
> This sounds like very much vendor specific optimization thing which am not
> 100% sure atm. If dt maintainers are okay, may be we can add an increment
> in the "ascii-mac-address" binding itself.
>
> Do you think "increment-at " would ever change?
Currently there's just one such real world use case in OpenWrt tree[1].
Probably some vendor decided to increment 4th octet.
> This [1] is what I had suggested at the end, where in its possible to add
> provider node with its own custom bindings. In above example nvmem_dev would
> be a proper nvmem provider.
Ok, thanks.
1. https://git.openwrt.org/?p=openwrt/openwrt.git;a=blob;f=target/linux/ath79/dts/ar9331_embeddedwireless_dorin.dts;h=43bec35fa2860fe4d52880ad24ff7c56f5060a0a;hb=HEAD#l109
-- ynezz
