On 06/27/2017 10:29 AM, Maxime Ripard wrote: > 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 ha> - it uses an undocumented value, with an unclear implication No it's no longer undocumented since [1] https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git/commit/?id=29b65f5f97632722bb80969377e5b0e2401fb392 Due to the timezone difference, you guys have already managed to have several exchanges, hopefully I will have a chance to review your discussions a little later today. -- Florian -- 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
