Re: [PATCH net-next v2 01/35] dt-bindings: phy: Add QorIQ SerDes binding

On 30/06/2022 20:01, Sean Anderson wrote:

Hi Rob,

On 6/30/22 1:27 PM, Rob Herring wrote:

quoted

On Tue, Jun 28, 2022 at 06:13:30PM -0400, Sean Anderson wrote:

quoted

This adds a binding for the SerDes module found on QorIQ processors. The
phy reference has two cells, one for the first lane and one for the
last. This should allow for good support of multi-lane protocols when
(if) they are added. There is no protocol option, because the driver is
designed to be able to completely reconfigure lanes at runtime.
Generally, the phy consumer can select the appropriate protocol using
set_mode. For the most part there is only one protocol controller
(consumer) per lane/protocol combination. The exception to this is the
B4860 processor, which has some lanes which can be connected to
multiple MACs. For that processor, I anticipate the easiest way to
resolve this will be to add an additional cell with a "protocol
controller instance" property.

Each serdes has a unique set of supported protocols (and lanes). The
support matrix is stored in the driver and is selected based on the
compatible string. It is anticipated that a new compatible string will
need to be added for each serdes on each SoC that drivers support is
added for. There is no "generic" compatible string for this reason.

There are two PLLs, each of which can be used as the master clock for
each lane. Each PLL has its own reference. For the moment they are
required, because it simplifies the driver implementation. Absent
reference clocks can be modeled by a fixed-clock with a rate of 0.

Signed-off-by: Sean Anderson <redacted>
---

Changes in v2:
- Add #clock-cells. This will allow using assigned-clocks* to configure
  the PLLs.
- Allow a value of 1 for phy-cells. This allows for compatibility with
  the similar (but according to Ioana Ciornei different enough) lynx-28g
  binding.
- Document phy cells in the description
- Document the structure of the compatible strings
- Fix example binding having too many cells in regs
- Move compatible first
- Refer to the device in the documentation, rather than the binding
- Remove minItems
- Rename to fsl,lynx-10g.yaml
- Use list for clock-names

 .../devicetree/bindings/phy/fsl,lynx-10g.yaml | 93 +++++++++++++++++++
 1 file changed, 93 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/phy/fsl,lynx-10g.yaml

diff --git a/Documentation/devicetree/bindings/phy/fsl,lynx-10g.yaml b/Documentation/devicetree/bindings/phy/fsl,lynx-10g.yaml
new file mode 100644
index 000000000000..b5a6f631df9f
--- /dev/null
+++ b/Documentation/devicetree/bindings/phy/fsl,lynx-10g.yaml

@@ -0,0 +1,93 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/phy/fsl,lynx-10g.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: NXP Lynx 10G SerDes
+
+maintainers:
+  - Sean Anderson <sean.anderson@seco.com>
+
+description: |
+  These Lynx "SerDes" devices are found in NXP's QorIQ line of processors. The
+  SerDes provides up to eight lanes. Each lane may be configured individually,
+  or may be combined with adjacent lanes for a multi-lane protocol. The SerDes
+  supports a variety of protocols, including up to 10G Ethernet, PCIe, SATA, and
+  others. The specific protocols supported for each lane depend on the
+  particular SoC.
+
+properties:
+  compatible:
+    description: |
+      Each compatible is of the form "fsl,<soc-name>-serdes-<instance>".
+      Although many registers are compatible between different SoCs, the
+      supported protocols and lane assignments tend to be unique to each SerDes.
+      Additionally, the method of activating protocols may also be unique.

We typically have properties for handling these variables. Numbering 
instances is something we avoid.

On v1, Krzysztof said that this was a better route...

I commented about "-1" and "-2" saying you have to make them properties.
You disagreed and with long messages were convincing me that "-1" and
"-2" is the only reasonable approach. I never said it is a better route.
I explicitly asked in several places for defining these as properties,
not as compatibles.

You are twisting the entire discussion now.

Best regards,
Krzysztof