Re: [PATCH v2] serial: qcom-geni: Set the serial engine up again after hibernation

[sashiko-bot@kernel.org]

> A hibernation image is restored after a power cycle, which resets every
> serial engine. The kernel that loads the image only sets up the engines
> it uses itself, and on laptops the Bluetooth UART is opened from the
> root file system, so that kernel never touches it.
> 
> The restored kernel still has port->setup set from before, so the
> startup in uart_resume_port() skips qcom_geni_serial_port_setup() and
> the port runs on an engine whose FIFOs, packing and transfer mode were
> never configured. On a Lenovo Yoga Slim 7x (X1E80100) the WCN7850's
> Bluetooth controller then never comes back: every setup attempt of
> hci_qca's error recovery ends in "command 0xfc00 tx timeout" and
> "Reading QCA version information failed (-110)".
> 
> Clear port->setup in a restore callback of its own, so the next startup
> sets the engine up again. Leave console ports alone: the kernel that
> loads the image sets up its console when it registers it, and setting
> the engine up again in qcom_geni_serial_startup() would run without the
> port lock while the console may be writing. The other system sleep
> callbacks are unchanged.
> 
> Signed-off-by: Birk Skyum <birk.skyum@pm.me>

Sashiko has reviewed this patch and found no issues.

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Sashiko AI review · https://sashiko.dev/#/patchset/20261027224800.86418-1-birk.skyum@pm.me?part=1