Re: [PATCH net-next v2 09/10] Documentation: add Device tree bindings for Broadcom GENET

Hi Mark,

2014-02-13 3:13 GMT-08:00 Mark Rutland [off-list ref]:

On Thu, Feb 13, 2014 at 05:29:54AM +0000, Florian Fainelli wrote:

quoted

This patch adds the Device Tree bindings for the Broadcom GENET Gigabit
Ethernet controller. A bunch of examples are provided to illustrate the
versatile aspect of the hardare.

Signed-off-by: Florian Fainelli <redacted>
---
Changes since v1:
- rebased

 .../devicetree/bindings/net/broadcom-bcmgenet.txt  | 111 +++++++++++++++++++++
 1 file changed, 111 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/net/broadcom-bcmgenet.txt

diff --git a/Documentation/devicetree/bindings/net/broadcom-bcmgenet.txt b/Documentation/devicetree/bindings/net/broadcom-bcmgenet.txt
new file mode 100644
index 0000000..93c58e9
--- /dev/null
+++ b/Documentation/devicetree/bindings/net/broadcom-bcmgenet.txt

@@ -0,0 +1,111 @@
+* Broadcom BCM7xxx Ethernet Controller (GENET)
+
+Required properties:
+- compatible: should be "brcm,genet-v1", "brcm,genet-v2", "brcm,genet-v3",
+  "brcm,genet-v4".

Presumably "should contain one of" is a better description than "should
be"?

Are the newer revisions compatible with older revisions?

Not entirely, the driver has internal macros: GENET_IS_V<N>() to help
figuring out which parts are different.

quoted

+- reg: address and length of the register set for the device.
+- interrupts: interrupt for the device
+- mdio bus node: this node should always be present regarless of the PHY
+  configuration of the GENET instance

Nit: a node is not a property, list it after properties.

quoted

+- phy-mode: The interface between the SoC and the PHY (a string that
+  of_get_phy_mode() can understand).

Do we not have a document under bindings listing these? I really don't
like referring to code in bindings docs.

Sergei has been working on a patch that centralizes the Ethernet DT
binding, but I am targetting the net-next/master tree in which this is
not yet present. I could probably pro-actively mention it though.

quoted

+
+MDIO bus node required properties:
+
+- compatible: should be "brcm,genet-v<N>-mdio"

Where N is? Could this not be an explicit list as above? It helps when
searching for bindings.

Yes, this should match the genet-v<N> compatible string.

quoted

+- reg: address and length relative to the parent node base register address

The parent node will require #address-cells and #size-cells too then.

Correct.

quoted

+- address-cells: address cell for MDIO bus addressing, should be 1
+- size-cells: size of the cells for MDIO bus addressing, should be 0
+
+Optional properties:
+- phy-handle: A phandle to a phy node defining the PHY address (as the reg
+  property, a single integer), used to describe configurations where a PHY
+  (internal or external) is used.

Is there not a phy binding you could refer to instead?

This is ePAPR, but once again, Sergei's document centralizes that nicely.

quoted

+
+- fixed-link: When the GENET interface is connected to a MoCA hardware block
+  or when operating in a RGMII to RGMII type of connection, or when the
+  MDIO bus is voluntarily disabled, this property should be used to describe
+  the "fixed link", the property is described as follows:
+
+  fixed-link: <a b c d e> where a is emulated phy id - choose any,
+  but unique to the all specified fixed-links, b is duplex - 0 half,
+  1 full, c is link speed - d#10/d#100/d#1000, d is pause - 0 no
+  pause, 1 pause, e is asym_pause - 0 no asym_pause, 1 asym_pause.

Is this not documented elsewhere such that it can be referred to?

The Freescale FEC driver is the one holding most of the documentation
for fixed-link, I can refer to it until Sergei's patch which
centralizes the Ethernet DT bindings gets merged.

quoted

+
+Internal Gigabit PHY example:
+
+ethernet@f0b60000 {
+     phy-mode = "internal";
+     phy-handle = <&phy1>;
+     mac-address = [ 00 10 18 36 23 1a ];
+     compatible = "brcm,genet-v4";
+     #address-cells = <0x1>;
+     #size-cells = <0x1>;
+     device_type = "ethernet";

What's this needed by? I can't see any other devices with this
device_type, and I was under the impression that we didn't want new
device_type properties cropping up.

This is just an oversight, and is not required per-se, I will get it removed.

quoted

+     reg = <0xf0b60000 0xfc4c>;
+     interrupts = <0x0 0x14 0x0 0x0 0x15 0x0>;

How many? The binding implied only one, and I'm not away of any
interrupt controller bindings with #interrupt-cells = <6>.

In fact, only two interrupts, cells, this is a bad copy-pasting from
the bootloader providing the DTB.

Thanks for the review!
-- 
Florian
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