On 28/10/2022 13:31, Thierry Reding wrote:

On Wed, Oct 26, 2022 at 08:13:57AM +0100, Jon Hunter wrote:

quoted

On 24/10/2022 08:41, Wayne Chang wrote:

quoted

add device-tree binding documentation for Cypress cypd4226 type-C
controller's I2C interface. It is a standard i2c slave with GPIO
input as IRQ interface.

Signed-off-by: Wayne Chang <redacted>
---
   .../bindings/usb/cypress,cypd4226.yaml        | 86 +++++++++++++++++++
   1 file changed, 86 insertions(+)
   create mode 100644 Documentation/devicetree/bindings/usb/cypress,cypd4226.yaml

diff --git a/Documentation/devicetree/bindings/usb/cypress,cypd4226.yaml b/Documentation/devicetree/bindings/usb/cypress,cypd4226.yaml
new file mode 100644
index 000000000000..5ac28ab4e7a1
--- /dev/null
+++ b/Documentation/devicetree/bindings/usb/cypress,cypd4226.yaml

@@ -0,0 +1,86 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/usb/cypress,cypd4226.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Cypress cypd4226 UCSI I2C Type-C Controller
+
+maintainers:
+  - Wayne Chang <waynec@nvidia.com>
+
+description: |
+  The Cypress cypd4226 UCSI I2C type-C controller is a I2C interface type-C
+  controller.
+
+properties:
+  compatible:
+    const: cypress,cypd4226
+
+  '#address-cells':
+    const: 1
+
+  '#size-cells':
+    const: 0
+
+  reg:
+    const: 0x08
+
+  interrupts:
+    maxItems: 1
+
+  cypress,firmware-build:
+    enum:
+      - nv
+      - gn
+    description: |
+      the name of the CCGx firmware built for product series.
+      should be set one of following:
+      - "nv" for the RTX product series

Please add 'NVIDIA' so that it is 'for the NVIDIA RTX product series'

quoted

+      - "gn" for the Jetson product series

Same here please add 'NVIDIA' so that it is 'for the NVIDIA Jetson product
series'.

Rob, any concerns about this property in general? Unfortunately, ACPI choose
a 16-bit type for this and used 'nv' for the RTX product. I don't find 'gn'
for Jetson very descriptive but we need a way to differentiate from RTX.

This is needed in the Cypress CCGX driver for the following ...

https://lore.kernel.org/lkml/20220928150840.3804313-1-waynec@nvidia.com/ (local)

Ideally, this should have been included in this series but was sent before.
We can always re-work/update the above patch even though it has been queued
up now.

The driver seems to use this 16-bit value only to compare with a
corresponding field in the firmware headers. How exactly we obtain this
value is therefore not important. However, since this 16-bit value is
embedded in firmware images, we also cannot substitute them with
something more sensible.

I am actually wondering if this is actually embedded in any images 
because I see it populated by the i2c-nvidia-gpu.c driver [0]. So I am 
wondering if we can use PROPERTY_ENTRY_STRING() for this driver instead 
and have a more descriptive name such as 'nvidia,rtx'?

Jon

[0] 
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/i2c/busses/i2c-nvidia-gpu.c#n261
-- 
nvpublic

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