On 10/3/23 14:21, Tony Lindgren wrote:
* Tony Lindgren <tony@xxxxxxxxxxx> [231003 12:15]:
Hi,
* Maximilian Luz <luzmaximilian@xxxxxxxxx> [231003 11:57]:
A bad workaround is to disable runtime PM, e.g. via
echo on > /sys/bus/serial-base/devices/dw-apb-uart.4:0/dw-apb-uart.4:0.0/power/control
If the touchscreen controller driver(s) are using serdev they are
children of the dw-apb-uart.4:0.0 and can use runtime PM calls to
block the parent device from idling as necessary. The hierarchy
unless changed using ignore_children.
Sorry about all the typos, I meant "the hierarchy works unless changed"
above. The rest of the typos are easier to decipher probably :)
Unfortunately that doesn't quite line up with what I can see on v6.5.5. The
serdev controller seems to be a child of dw-apb-uart.4, a platform device. The
serial-base and serdev devices are siblings. According to sysfs:
/sys/bus/platform/devices/dw-apb-uart.4
├── driver -> ../../../../bus/platform/drivers/dw-apb-uart
├── subsystem -> ../../../../bus/platform
│
├── dw-apb-uart.4:0
│ ├── driver -> ../../../../../bus/serial-base/drivers/ctrl
│ ├── subsystem -> ../../../../../bus/serial-base
│ │
│ └── dw-apb-uart.4:0.0
│ ├── driver -> ../../../../../../bus/serial-base/drivers/port
│ └── subsystem -> ../../../../../../bus/serial-base
│
└── serial0
├── subsystem -> ../../../../../bus/serial
│
└── serial0-0
├── driver -> ../../../../../../bus/serial/drivers/surface_serial_hub
└── subsystem -> ../../../../../../bus/serial
Runtime suspend on serial0-0 is disabled/not set up at all. So I assume that if
it were a descendent of dw-apb-uart.4:0.0, things should have worked
out-of-the-box.
Regards,
Max
