Re: [PATCH v5 1/2] dt-bindings: usb: add analogix,anx7688.yaml

Hi Dafna,

Many thanks to take this challenge and work on this.

On 30/3/21 15:35, Dafna Hirschfeld wrote:

Hi,

On 05.03.21 16:19, Laurent Pinchart wrote:

quoted

Hi Dafna,

On Fri, Mar 05, 2021 at 04:14:03PM +0100, Dafna Hirschfeld wrote:

quoted

On 05.03.21 15:34, Laurent Pinchart wrote:

quoted

On Fri, Mar 05, 2021 at 01:43:50PM +0100, Dafna Hirschfeld wrote:

quoted

ANX7688 is a USB Type-C port controller with a MUX. It converts HDMI 2.0 to
DisplayPort 1.3 Ultra-HDi (4096x2160p60).
The integrated crosspoint switch (the MUX) supports USB 3.1 data transfer
along with the DisplayPort Alternate Mode signaling over USB Type-C.
Additionally, an on-chip microcontroller (OCM) is available to manage the
signal switching, Channel Configuration (CC) detection, USB Power
Delivery (USB-PD), Vendor Defined Message (VDM) protocol support and other
functions as defined in the USB TypeC and USB Power Delivery
specifications.

ANX7688 is found on Acer Chromebook R13 (elm) and on
Pine64 PinePhone.

Signed-off-by: Dafna Hirschfeld <redacted>
---
   .../bindings/usb/analogix,anx7688.yaml        | 177 ++++++++++++++++++
   1 file changed, 177 insertions(+)
   create mode 100644
Documentation/devicetree/bindings/usb/analogix,anx7688.yaml

diff --git a/Documentation/devicetree/bindings/usb/analogix,anx7688.yaml

b/Documentation/devicetree/bindings/usb/analogix,anx7688.yaml
new file mode 100644
index 000000000000..6c4dd6b4b28b

--- /dev/null
+++ b/Documentation/devicetree/bindings/usb/analogix,anx7688.yaml

@@ -0,0 +1,177 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/usb/analogix,anx7688.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Analogix ANX7688 Type-C Port Controller with HDMI to DP conversion
+
+maintainers:
+  - Nicolas Boichat <drinkcat@chromium.org>
+  - Enric Balletbo i Serra <enric.balletbo@collabora.com>
+
+description: |
+  ANX7688 is a USB Type-C port controller with a MUX. It converts HDMI 2.0 to
+  DisplayPort 1.3 Ultra-HDi (4096x2160p60).
+  The integrated crosspoint switch (the MUX) supports USB 3.1 data

transfer along with
+  the DisplayPort Alternate Mode signaling over USB Type-C. Additionally,
+  an on-chip microcontroller (OCM) is available to manage the signal
switching,
+  Channel Configuration (CC) detection, USB Power Delivery (USB-PD), Vendor
+  Defined Message (VDM) protocol support and other functions as defined in
the
+  USB TypeC and USB Power Delivery specifications.
+
+

Extra blank line ?

quoted

+properties:
+  compatible:
+    const: analogix,anx7688
+
+  reg:
+    maxItems: 1
+
+  avdd33-supply:
+    description: 3.3V Analog core supply voltage.
+
+  dvdd18-supply:
+    description: 1.8V Digital I/O supply voltage.
+
+  avdd18-supply:
+    description: 1.8V Analog core power supply voltage.
+
+  avdd10-supply:
+    description: 1.0V Analog core power supply voltage.
+
+  dvdd10-supply:
+    description: 1.0V Digital core supply voltage.
+

That's lots of supplies. If there's a reasonable chance that some of
them will always be driven by the same regulator (especially if the
ANX7688 documentation requires that), then they could be grouped. For
instance dvdd18-supply and avdd18-supply could be grouped into
vdd18-supply. It would still allow us to extend the bindings in a
backward compatible way later if a system uses different regulators. You
have more information about the hardware than I do, so it's your call.

Can you explain what do you mean by 'grouped' ?
Do you mean that instead of having two properties dvdd18-supply and avdd18-supply
I have only one property vdd18-supply?

You can simplify all this with vdd33, vdd18 vdd10. For the Chromebook case all
the analogic and digital part are the same regulator just filtered. That's a
common configuration and if there is some hardware that needs it we can extend
later.

quoted

quoted

quoted

quoted

+  hdmi5v-supply:
+    description: 5V power supply for the HDMI.
+
+  hdmi_vt-supply:
+    description: Termination voltage for HDMI input.

Maybe hdmi-vt-supply ?

quoted

+
+  clocks:
+    description: The input clock specifier.
+    maxItems: 1

How about

      items:
        - description: The input clock specifier.

quoted

+
+  clock-names:
+    items:
+      - const: xtal
+
+  hpd-gpios:
+    description: |
+      In USB Type-C applications, DP_HPD has no use. In standard DisplayPort
+      applications, DP_HPD is used as DP hot-plug.
+    maxItems: 1
+
+  enable-gpios:
+    description: Chip power down control. No internal pull-down or pull-up
resistor.
+    maxItems: 1
+
+  reset-gpios:
+    description: Reset input signal. Active low.
+    maxItems: 1
+
+  vbus-det-gpios:
+    description: |
+      An input gpio for VBUS detection and high voltage detection,
+      external resistance divide VBUS voltage to 1/8.
+    maxItems: 1
+
+  interrupts:
+    description: |
+      The interrupt notifies 4 possible events - TCPC ALERT int, PD int,
DP int, HDMI int.
+    maxItems: 1
+
+  cabledet-gpios:
+    description: An output gpio, indicates by the device that a cable is
plugged.
+    maxItems: 1
+
+  vbus-ctrl-gpios:
+    description:
+      External VBUS power path. Enable VBUS source and disable VBUS sink
or vice versa.
+    maxItems: 1
+
+  vconn-en1-gpios:
+    description: Controls the VCONN switch on the CC1 pin.
+    maxItems: 1
+
+  vconn-en2-gpios:
+    description: Controls the VCONN switch on the CC2 pin.
+    maxItems: 1
+
+  ports:
+    $ref: /schemas/graph.yaml#/properties/ports
+
+    properties:
+      port@0:
+        $ref: /schemas/graph.yaml#/properties/port
+        description: Video port for HDMI input.
+
+      port@1:
+        $ref: /schemas/graph.yaml#/properties/port
+        description: USB port for the USB3 input.
+
+      port@2:
+        $ref: /schemas/graph.yaml#/properties/port
+        description: USB Type-c connector, see connector/usb-connector.yaml.
+
+    required:
+      - port@0

As all the ports exist at the hardware level, should they always be
present ? The endpoints are optional of course, in case a port isn't
connected on a particular system.

quoted

+
+required:
+  - compatible
+  - reg

Shouldn't clocks and regulators be also required ?

hmm, theoretically yes. Practically, in the case of Acer R13 (mediatek elm)
device,
the ANX7688 is powered up and controlled by the Embedded Controller. The
kernel only
needs to read few registers from that device for the drm bridge driver.
(also mentioned that in the cover letter).

I think that for the Chromebook you can assume that these supplies are a
fixed-regulator that are always on.

quoted

This may not be a popular opinion, but if the ANX7688 is fully
controlled by the EC, I wonder if we shouldn't have an "EC DRM bridge"
driver that would interrogate the EC instead :-)

We can do this, and tbh will be more easy for us, but we were already asked to
do it generic, so ...

But the driver in patch 2/2 do access the anx7688 device with I2C.
It does interrogate the EC.

quoted

Is there a risk of bus conflicts if the EC and the main SoC try to
access the ANX7688 over I2C at the same time ?

No, there is a kind of i2c tunnel but you don't talk directly with the ANX7688.
The EC exposes the anx bus control to the AP.

The SoC access the anx7688 though something called 'i2c-tunnel' (see
google,cros-ec-i2c-tunnel.yaml)
So the I2C tunnels though the EC (I don't know how this is really implemented to
be honest).


Thanks,
Dafna

quoted

quoted

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Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

quoted

+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    #include <dt-bindings/interrupt-controller/irq.h>
+
+    i2c0 {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        anx7688: anx7688@2c {
+            compatible = "analogix,anx7688";
+            reg = <0x2c>;
+            avdd33-supply = <&reg_dcdc1>;
+            dvdd18-supply = <&reg_ldo_io1>;
+            avdd18-supply = <&reg_ldo_io1>;
+            avdd10-supply = <&reg_anx1v0>;
+            dvdd10-supply = <&reg_anx1v0>;
+            hdmi_vt-supply = <&reg_dldo1>;
+            enable-gpios = <&pio 3 10 GPIO_ACTIVE_LOW>; /* PD10 */
+            reset-gpios = <&pio 3 6 GPIO_ACTIVE_HIGH>; /* PD6 */
+            interrupt-parent = <&r_pio>;
+            interrupts = <0 11 IRQ_TYPE_EDGE_FALLING>; /* PL11 */
+            cabledet-gpios = <&r_pio 0 8 GPIO_ACTIVE_HIGH>; /* PL8 */
+            vconn-en1-gpios = <&pio 3 9 GPIO_ACTIVE_LOW>; /* PD9 */
+            vconn-en2-gpios = <&pio 3 9 GPIO_ACTIVE_LOW>; /* PD9 */
+            ports {
+                #address-cells = <1>;
+                #size-cells = <0>;
+
+                port@0 {
+                    reg = <0>;
+                    anx7688_in0: endpoint {
+                        remote-endpoint = <&hdmi0_out>;
+                    };
+                };
+
+                port@1 {
+                    reg = <1>;
+                    anx7688_in1: endpoint {
+                        remote-endpoint = <&usbdrd_phy_ss>;
+                    };
+                };
+                port@2 {
+                    reg = <2>;
+                    anx7688_out: endpoint {
+                        remote-endpoint = <&typec_connector>;
+                    };
+                };
+            };
+        };
+    };