于 2017年6月27日 GMT+08:00 下午6:15:58, Andre Przywara [off-list ref] 写到:

Hi,

On 27/06/17 10:41, Maxime Ripard wrote:

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On Tue, Jun 27, 2017 at 10:02:45AM +0100, Andre Przywara wrote:

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Hi,

(CC:ing some people from that Rockchip dmwac series)

On 27/06/17 09:21, Corentin Labbe wrote:

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On Tue, Jun 27, 2017 at 04:11:21PM +0800, Chen-Yu Tsai wrote:

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On Tue, Jun 27, 2017 at 4:05 PM, Corentin Labbe
[off-list ref] wrote:

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On Mon, Jun 26, 2017 at 01:18:23AM +0100, André Przywara wrote:

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On 31/05/17 08:18, Corentin Labbe wrote:

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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

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register function.

Hi,

I know I am a bit late with this, but while adapting the U-Boot

driver

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to the new binding I was wondering about the internal PHY

detection:

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So here you seem to deduce the usage of the internal PHY by the

PHY

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interface specified in the DT (MII = internal, RGMII =

external).

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I think I raised this question before, but isn't it perfectly

legal for

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a board to use MII with an external PHY even on those SoCs that

feature

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an internal PHY?
On the first glance that does not make too much sense, but apart

from

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not being the correct binding to describe all of the SoCs

features I see

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two scenarios:
1) A board vendor might choose to not use the internal PHY

because it

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has bugs, lacks features (configurability) or has other issues.

For

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instance I have heard reports that the internal PHY makes the

SoC go

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rather hot, possibly limiting the CPU frequency. By using an

external

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MII PHY (which are still cheaper than RGMII PHYs) this can be

avoided.

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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

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IC or some other network circuitry, for instance fibre

connectors.

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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

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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

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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

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I'm not a fan of using phy-mode for this. There's no guarantee

what

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mode the internal PHY uses. That's what phy-mode is for.

I can understand Chen-Yu's concerns, but ...

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For each soc the internal PHY mode is know and setted in

emac_variant/internal_phy

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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

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of the internal PHY would be nice, I am bit tempted to use this

easier

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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.

                   reg = <1>;
                   clocks = <&ccu CLK_BUS_EPHY>;
                   resets = <&ccu RST_BUS_EPHY>;
               };
           };
       };

And then move the internal-PHY setup code into a separate PHY driver?

That looks like the architecturally best solution to me, but is
probably
also a bit involved since it would require a separate PHY driver.
Or can we make it simpler, but still use this binding?

Cheers,
Andre.

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