On Fri, 2014-08-29 at 05:18PM +0200, Andreas Färber wrote: > Am 29.08.2014 16:08, schrieb Michal Simek: > > 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. > > Sorry, but we do need some node that we can reference via phy-handle > from the gem node, don't we? > > In that case, is not specifying any compatible string a valid option? > > If you don't want to specify the IDs, then I would've assumed we need to > specify the -c22 in order to have *some* compatible string in order to > trigger loading of the appropriate driver module. The compatible string is listed as optional property for PHYs. So, not having one is an option, I guess. But, I'd also prefer to at least keep the -c22 one, since I saw problems when I tried using -c45 (the Zed phy should support it...). Also, so far, we haven't had any phy nodes in our Zynq dts files and Ethernet worked, so the auto-detection there works pretty well apparently. But it may be problematic if more than a single PHY is on the MDIO bus, I'd assume. Sören -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
