On 08/25/2014 10:21 PM, Florian Fainelli wrote: > On 08/25/2014 10:46 AM, Jason Gunthorpe wrote: >> On Fri, Aug 22, 2014 at 01:47:09PM -0700, Florian Fainelli wrote: >> >>>> - the ID based strings seem to be not needed since, IIUC, the core >>>> reads the ID from the PHY and uses it, so I just left it out not >>>> trying to figure out how to obtain the correct ID >>> >>> It is not needed, but it is one way to specify a PHY device if you do >>> not know what compatible string to use instead. >> >> No, it is a way to specify a PHY device if the kernel can't auto probe >> the Phy ID. >> >> Last I checked, the kernel doesn't support plain text compatible >> strings for phys - everything is driven on the phy id, either auto >> probed or specified in the DT. > > That's right. Some PHY drivers might be relying on specific compatible > strings though, but not the core PHY library that probes and maps a > driver to a PHY node. > >> >>>> - the marvell compatible strings are used in our vendor tree. They >>>> aren't used anywhere but in our vendor tree. I though keeping them is >>>> nice since it identifies the PHY fully. And in case that level of >>>> detail is needed at some point it is already there. >>> >>> And this is the recommended way to do it in case we ever need to key a >>> software decision based on the hardware. >> >> All compatible strings need to be documented. >> >> .. and they need to encode more information than you get from the phy >> id - die revsision, package option, functional options, voltage >> codes. Etc. >> >> .. and they actually need to be *right* > > Agreed. > >> >> An example: The kernel reports 88E1318S for all four chips in that >> family, AFAIK you have to read the package marking to figure out which >> you have (it is the same die, with options switched on/off at >> packaging time). People have already posted patches trying to >> helpfully add a 'marvell,88E1318S' compatible string based on kernel >> output. Except it is wrong, it isn't actually the '8S version in the >> HW. >> >> Even worse, Marvell has a whole series of socket compatible phys. Just >> because the board the DT author looked at has a '318, doesn't mean >> that every board ever made will. We've actually already been switching >> between the 318 and 318S for production depending on which has part >> availability. >> >> Basically: don't try to override self-discoverable hardware in DT >> without a really good reason. > > I think that's a very good point, at the very least let's use a > compatible string that contains the full 32-bits PHY OUI. I think resolution is: 1. Do not use marvell,88e1518 because it is not listed anywhere 2. Do not add ethernet-phy-idAAAA.BBBB because it breaks autodetection if there is different phy on the board and we shouldn't restrict us in this. In spite of autodetection takes some time. 3. "ethernet-phy-ieee802.3-c22" is optional that's why doesn't need to be added 4. Any listed compatible string has to be parsed which takes time That's why I think make sense not to use any compatible string. This should give us all flexibility which we want to have. Thanks, Michal
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