Re: Re: [PATCH 2/4] dt-bindings: add binding for RTL8211E Ethernet PHY

于 2017年5月5日 GMT+08:00 上午2:21:29, Florian Fainelli [off-list ref] 写到:

On 05/04/2017 11:10 AM, icenowy-h8G6r0blFSE@public.gmane.org wrote:

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在 2017-04-22 08:22，Florian Fainelli 写道：

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On 04/21/2017 04:24 PM, Icenowy Zheng wrote:

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From: Icenowy Zheng <redacted>

Some RTL8211E Ethernet PHY have an issue that needs a workaround
indicated with device tree.

Add the binding for a property that indicates this workaround.

Signed-off-by: Icenowy Zheng <redacted>
---
 .../devicetree/bindings/net/realtek,rtl8211e.txt   | 22
++++++++++++++++++++++
 1 file changed, 22 insertions(+)
 create mode 100644
Documentation/devicetree/bindings/net/realtek,rtl8211e.txt

diff --git
a/Documentation/devicetree/bindings/net/realtek,rtl8211e.txt
b/Documentation/devicetree/bindings/net/realtek,rtl8211e.txt
new file mode 100644
index 000000000000..c1913301bfe8

--- /dev/null
+++ b/Documentation/devicetree/bindings/net/realtek,rtl8211e.txt

@@ -0,0 +1,22 @@
+Realtek RTL8211E Ethernet PHY
+
+One batch of RTL8211E is slight broken, that needs some special

(and

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+full of magic numbers) tweaking in order to make GbE to operate
properly.
+The only well-known board that used the broken batch is Pine64+.
+Configure it through an Ethernet OF device node.
+
+Optional properties:
+
+- realtek,disable-rx-delay:
+  If set, RX delay will be completely disabled (according to
Realtek). This
+  will affect the performance on non-broken boards.
+  default: do not disable RX delay.

Please don't introduce custom properties to do that, instead correct
specify the "phy-mode" such that it is e.g: "rgmii-txid" which

indicates

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that there should be no RX internal delay, but a TX internal delay

added

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by the PHY.

Checked the document, the meaning of "rgmii-txid" is not correct

here.

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This doesn't effect the MAC, and the MAC should still add TX delay.

The definition of "rgmii-txid" in
Documentation/devicetree/binding/net/ethernet.txt is "RGMII with
internal TX delay provided by the PHY, the MAC should not add an TX

delay

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in this case". However, this do not indicate that the MAC doesn't add

TX

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delay; in fact that just totally disabled the PHY to provide the RX

delay.

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MAC still should to add delay on both TX/RX, which is the semantic of
standard "rgmii".

So I cannot used "rgmii-txid" here, but should continue to use this
custom property.

This is absolutely not a correct understanding. The 'phy-mode' property
defines the contract between the MAC and PHY. It is defined from the
PHY's perspective of the delay, which means that the MAC has to either
also provide an adequate delay (RX or TX) or not (RX or TX). So if you
specified 'phy-mode' = "rgmii" this means that the MAC needs to adds
the
TX and RX delay, so implcitly this means that your MAC operates in

The MAC doesn't lose its responsibility to tweak RX/TX delays with this property set.

This situation is that, the PHY's RX delay tweaking function is broken. But it doesn't mean that the PHY can take over *all* responsibility to tweak TX, it still needs MAC to tweak TX.

"rgmii-id", if the property was defined from the perspective of the
MAC,
which it is not.

Both the Ethernet PHY driver and the MAC driver need to take care of
adjusting the delays based on the phydev->interface value.

The property you are introducing here is absolutely not appropriate
because it is entirely redundant with what 'phy-mode' already defines,
except the latter also covers a lot more cases.

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