Hi,
On 05.03.21 18:24, Ondřej Jirman wrote:
Hello Dafna,
On Fri, Mar 05, 2021 at 04:14:03PM +0100, Dafna Hirschfeld wrote:
Hi
On 05.03.21 15:34, Laurent Pinchart wrote:
Hi Dafna,
Thank you for the patch.
On Fri, Mar 05, 2021 at 01:43:50PM +0100, Dafna Hirschfeld wrote:
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.
Thanks for your work on the bindings. :) It would be great to find something
acceptable for mainlining.
A few comments based on my experience implementing the USB-PD part for PinePhone
are bellow.
+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.
On PinePhone, AVDD and DVDD for 1.0V are just separately fitlered outputs
from the same regulator. So it would work there to just use vdd18 and
vdd10. The same is true for reference design, so it's probably safe
to assume this can be simplified.
+ hdmi5v-supply:
+ description: 5V power supply for the HDMI.
+
+ hdmi_vt-supply:
+ description: Termination voltage for HDMI input.
Maybe hdmi-vt-supply ?
+
+ clocks:
+ description: The input clock specifier.
+ maxItems: 1
How about
items:
- description: The input clock specifier.
+
+ 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
On PinePhone this is wired to a HDMI port on the SoC, and HPD is handled by the
sun4i HDMI DRM driver. Seems like HPD will be handled by HDMI controller on
many/all? other platforms too. Why have it here?
Right, I didn't have the full picture when listing all the pins of the anx7688.
I was not sure what should be listed.
I will remove that.
+ 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
Why have this in the bindings? It seems that this is handled internally by the
ANX7688 via OCM firmware. And it's not really gpio either, it's an analog input
with AD converter hooked to it internally.
I will remove that.
+ 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
VBUS control seems to be already modelled by the usb-connector bindings. Why
have this here?
dito
+ 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
VCONN is a voltage regulator that can be enabled either on CC1 or CC2
pin, or disabled completely. This control is *partially* performed in reference
design directly by the OCM. OCM only decides which CC pin to switch
the VCONN regulator to, and informs the SoC when the base VCONN regulator
for the switches needs to be enabled.
So vconn-en1/2 gpios are irrelevant to the driver, but the driver needs
to control VCONN power supply somehow and defer control over it to the OCM.
I don't know how to express it in the bindings. Maybe a vconn-supply here
on the anx7688 node?
It may also be part of the usb-connector binding, but this is really when it
comes to anx7688 a parent regulator for the switches, and switches are not
controlled by this driver, just their parent regulator is.
Any ideas?
Looking at the diagram in the schematics, I see that both vbus-supply and vconn-supply
come directly from the PMIC so similarly to the vbus-supply, the vconn-supply
can be part of the usb-connector. Then a driver can access the vconn-supply from the remote usb
connector. Is there a problem with that?
Thanks a lot for the review, I am not very familiar with usb and type-c, so your review helps a lot.
I will send v6 soon.
Thanks,
Dafna
kind regards,
o.
+ 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.
+
+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).
Thanks,
Dafna
