On Tue, Jun 27, 2017 at 02:37:48PM +0200, Corentin Labbe wrote: > On Tue, Jun 27, 2017 at 11:33:56AM +0100, Andre Przywara wrote: > > Hi, > > > > On 27/06/17 11:23, Icenowy Zheng wrote: > > > > > > > > > 于 2017年6月27日 GMT+08:00 下午6:15:58, Andre Przywara <andre.przywara@xxxxxxx> 写到: > > >> Hi, > > >> > > >> On 27/06/17 10:41, Maxime Ripard wrote: > > >>> On Tue, Jun 27, 2017 at 10:02:45AM +0100, Andre Przywara wrote: > > >>>> Hi, > > >>>> > > >>>> (CC:ing some people from that Rockchip dmwac series) > > >>>> > > >>>> On 27/06/17 09:21, Corentin Labbe wrote: > > >>>>> On Tue, Jun 27, 2017 at 04:11:21PM +0800, Chen-Yu Tsai wrote: > > >>>>>> On Tue, Jun 27, 2017 at 4:05 PM, Corentin Labbe > > >>>>>> <clabbe.montjoie@xxxxxxxxx> wrote: > > >>>>>>> On Mon, Jun 26, 2017 at 01:18:23AM +0100, André Przywara wrote: > > >>>>>>>> On 31/05/17 08:18, Corentin Labbe wrote: > > >>>>>>>>> The dwmac-sun8i is a heavy hacked version of stmmac hardware by > > >>>>>>>>> allwinner. > > >>>>>>>>> In fact the only common part is the descriptor management and > > >> the first > > >>>>>>>>> register function. > > >>>>>>>> > > >>>>>>>> Hi, > > >>>>>>>> > > >>>>>>>> I know I am a bit late with this, but while adapting the U-Boot > > >> driver > > >>>>>>>> to the new binding I was wondering about the internal PHY > > >> detection: > > >>>>>>>> > > >>>>>>>> > > >>>>>>>> So here you seem to deduce the usage of the internal PHY by the > > >> PHY > > >>>>>>>> interface specified in the DT (MII = internal, RGMII = > > >> external). > > >>>>>>>> I think I raised this question before, but isn't it perfectly > > >> legal for > > >>>>>>>> a board to use MII with an external PHY even on those SoCs that > > >> feature > > >>>>>>>> an internal PHY? > > >>>>>>>> On the first glance that does not make too much sense, but apart > > >> from > > >>>>>>>> not being the correct binding to describe all of the SoCs > > >> features I see > > >>>>>>>> two scenarios: > > >>>>>>>> 1) A board vendor might choose to not use the internal PHY > > >> because it > > >>>>>>>> has bugs, lacks features (configurability) or has other issues. > > >> For > > >>>>>>>> instance I have heard reports that the internal PHY makes the > > >> SoC go > > >>>>>>>> rather hot, possibly limiting the CPU frequency. By using an > > >> external > > >>>>>>>> MII PHY (which are still cheaper than RGMII PHYs) this can be > > >> avoided. > > >>>>>>>> 2) A PHY does not necessarily need to be directly connected to > > >>>>>>>> magnetics. Indeed quite some boards use (RG)MII to connect to a > > >> switch > > >>>>>>>> IC or some other network circuitry, for instance fibre > > >> connectors. > > >>>>>>>> > > >>>>>>>> So I was wondering if we would need an explicit: > > >>>>>>>> allwinner,use-internal-phy; > > >>>>>>>> boolean DT property to signal the usage of the internal PHY? > > >>>>>>>> Alternatively we could go with the negative version: > > >>>>>>>> allwinner,disable-internal-phy; > > >>>>>>>> > > >>>>>>>> Or what about introducing a new "allwinner,internal-mii-phy" > > >> compatible > > >>>>>>>> string for the *PHY* node and use that? > > >>>>>>>> > > >>>>>>>> I just want to avoid that we introduce a binding that causes us > > >>>>>>>> headaches later. I think we can still fix this with a followup > > >> patch > > >>>>>>>> before the driver and its binding hit a release kernel. > > >>>>>>>> > > >>>>>>>> Cheers, > > >>>>>>>> Andre. > > >>>>>>>> > > >>>>>>> > > >>>>>>> I just see some patch, where "phy-mode = internal" is valid. > > >>>>>>> I will try to find a way to use it > > >>>>>> > > >>>>>> Can you provide a link? > > >>>>> > > >>>>> https://lkml.org/lkml/2017/6/23/479 > > >>>>> > > >>>>>> > > >>>>>> I'm not a fan of using phy-mode for this. There's no guarantee > > >> what > > >>>>>> mode the internal PHY uses. That's what phy-mode is for. > > >>>> > > >>>> I can understand Chen-Yu's concerns, but ... > > >>>> > > >>>>> For each soc the internal PHY mode is know and setted in > > >> emac_variant/internal_phy > > >>>>> So its not a problem. > > >>>> > > >>>> that is true as well, at least for now. > > >>>> > > >>>> So while I agree that having a separate property to indicate > > >>>> the usage of the internal PHY would be nice, I am bit tempted > > >>>> to use this easier approach and piggy back on the existing > > >>>> phy-mode property. > > >>> > > >>> We're trying to fix an issue that works for now too. > > >>> > > >>> If we want to consider future weird cases, then we must > > >>> consider all of them. And the phy mode changing is definitely > > >>> not really far fetched. > > >>> > > >>> I agree with Chen-Yu, and I really feel like the compatible > > >>> solution you suggested would cover both your concerns, and > > >>> ours. > > >> > > >> So something like this? > > >> emac: emac@1c30000 { > > >> compatible = "allwinner,sun8i-h3-emac"; > > >> ... > > >> phy-mode = "mii"; > > >> phy-handle = <&int_mii_phy>; > > >> ... > > >> > > >> mdio: mdio { > > >> #address-cells = <1>; > > >> #size-cells = <0>; > > >> int_mii_phy: ethernet-phy@1 { > > >> compatible = "allwinner,sun8i-h3-ephy"; > > >> syscon = <&syscon>; > > > > > > The MAC still needs to set some bits of syscon register. > > > > Yes, the syscon property needs also to be in the MAC node, that > > was meant to be somewhere in the second "..." ;-) > > > > But now since Chen-Yu mentioned that we need to set up the PHY *first* > > to make it actually discoverable via MDIO, I wonder if we could change > > this to: > > 1) have the DT as described here > > 2) Let the dwmac-sun8i driver peek into the node referenced by > > phy-handle and check the compatible string there. > > 3) If that matches some allwinner internal PHY name, it sets up the PHY > > to make it respond when the MDIO driver queries its bus. > > > > Or can a PHY driver set itself up (since we have clocks and resets > > properties in there) *before* the MDIO bus gets scanned? > > Chen-Yu's comment in the other mail hints at that this is not easily > > possible. > > I think adding phy compatible just make things more complex. > > I think the patch series I sent early fix all problems without more > complexity since: > > - it does not add more DT stuff > - it use an already used in tree DT phy-mode "internal" (and so phy > mode PHY_INTERFACE_MODE_INTERNAL) - it doesn't cover all the concerns we had - it uses an undocumented value, with an unclear implication Maxime -- Maxime Ripard, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com
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