On Sun, Jul 18, 2021 at 9:09 PM Martin Blumenstingl
[off-list ref] wrote:

Hi Anand,

On Sun, Jul 18, 2021 at 4:01 PM Martin Blumenstingl
[off-list ref] wrote:
[...]

quoted

quoted

From the schematics [1]
https://dn.odroid.com/S805/Schematics/odroid-c1+_rev0.4_20160226.pdf

You could find references to PWREN  <--- GPIOAO.BIT5
The second reference is USB HOST Power Switch
The third reference is USB HOST POWER.

Hope I am clean in my thought process now.

Can you please point out the page numbers for me?

What I am seeing on page 1 is:
GPIOAO_5 (called GPIOAO.BIT5) is connected as an INPUT to the USB_OTG
PWREN signal (that's the green box with the label "USB_OTG.SchDoc"
above it).

I unfortunately missed your question on IRC on this topic:
<armoon> xdarklight: just want to understand the confusion on PWREN,
either is INPUT / OTPUT to usb hub am I correct
My understanding of the INPUT/OUTPUT direction in the Odroid-C1
schematics (which you linked) above is that the arrow direction shows
whether it's an input or output.
For example (all on page one):
- HDMI_HPD is an input to the Meson8b SoC, arrow direction is: HDMI => S805
- IR_IN is an input to the Meson8b SoC, arrow direction is: S805 <=
GPIOAO.BIT7 IR_IN
- PWM is an output, arrow direction is: S805 => PWM.C VCCK_PWM
- 3.3V/1.8V switch for the SD card is an output, arrow direction is:
S805 => GPIOAO.BIT3 TF_3V3N_1V8_EN

That tells me: the arrow direction shows which connections are inputs
or outputs.
Some pins can be input and output at the same time (HDMI_CEC). But
let's keep it simple for now any only look at inputs/output.

Based on this information I am looking at the arrow direction for
USB_OTG: GPIOAO.BIT5 PWREN <= S805
So this confirms that GPIOAO_5 is an output to the SoC.
Please note though that this part is not linked with any USB host
connector, it's only linked to the USB OTG path.

For the next part the S805 SoC is not involved:
USB1 USB_HOST_PWR_SW PWREN <= PWREN USB_HUB_GL852G
USB2 USB_HOST_PWR_SW PWREN <= PWREN USB_HUB_GL852G
This tells me that the PWREN signal for the two USB_HOST_PWR_SW (USB
host power switches / current limiters) is driven by the GL852G USB
hub.

Hardkernel team responded on the Odroid forums to the request from Anand:
"Power-Enable signal to the USB load switch ICs is connected to the
USB hub controller.
It is not connected the CPU GPIO."

The regulator from Anand's patch is therefore connected to the micro USB port.
This means that the patch needs updating in case Anand wants to have
it included.


Best regards,
Martin


[0] https://forum.odroid.com/viewtopic.php?p=332217#p332217