On 8/2/24 7:59 PM, Sebastian Reichel wrote:
Hi,
Hello everyone,
On ROCK 5B power is usually supplied via it's USB-C port. This port has the
data lines connected to RK3588, VBUS connected to the input regulator and
CC pins connected to FUSB302. FUSB302 is a USB-C controller, which can be
accessed via I2C from RK3588. The USB-C controller is needed to figure out
the USB-C cable orientation, but also to do USB PD communication. Thus it
would be great to enable support for it in the operating system.
But the USB-PD specification requires, that a device reacts to USB-PD messages
send by the power-supply within around 5 seconds. If that does not happen the
power-supply assumes, that the device does not support USB-PD. If a device
later starts sending USB-PD messages it is considered an error, which is solved
by doing a hard reset. A USB-PD hard reset means, that all supply voltages are
removed for a short period of time. For boards, which are solely powered
through their USB-C port, like the Radxa Rock 5B, this results in an machine
reset. This is currently worked around by not describing the FUSB302 in the
kernel DT, so nothing will ever speak USB-PD on the Rock 5B. This means
1. the USB-C port cannot be used at all
2. the board will be running via fallback supply, which provides limited
power capabilities
In order to avoid the hard reset, this adds FUSB302 support to U-Boot, so
that we react to the power-supply's queries in time. The code, which is
originally from the Linux kernel, consists of two parts:
1. the tcpm state machine, which implements the Type C port manager state
machine as described in the USB PD specification
2. the fusb302 driver, which knows about specific registers
Especially the first part has been heavily modified compared to the
kernel, which makes use of multiple delayed works and threads. For this
I used a priorly ported version from Rockchip, removed their hacks and
any states not necessary in U-Boot (e.g. audio accessory support).
Sorry for the delay in getting PATCHv3 ready.
I am the one who should be sorry here, really, sorry for the abysmal
delay in my replies.
So ... this series looks good to me. Thank you for working on this !
Jonas, are your concerns resolved ?
