serial: qcom-geni: Convert console to nbcon

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The legacy GENI console writer serializes every message around a
synchronous polled M-side transfer. It blocks printk callers for UART
wire time and cannot provide atomic output while normal console output is
active.

Convert the console to nbcon threaded and atomic writers. Use the UART
port lock as the device lock and bound threaded M-side commands so
urgent diagnostics can take over atomic output. The threaded writer is
batching the output in 32-source-byte commands, a value chosen to
balance the command setup overhead with atomic-handoff latency.

Atomic output can cancel an active normal TX command. Use irq_work to
resume queued TTY output afterward, honor flow control, and prevent the
deferred restart from accessing the port during shutdown or removal.

Assisted-by: OpenCode:GPT-5.5
Signed-off-by: Bjorn Andersson <bjorn.andersson@oss.qualcomm.com>
Link: https://patch.msgid.link/20260729-qcom-geni-nbcon-v1-1-3053b96465ed@oss.qualcomm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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Bjorn Andersson 2026-07-29 21:44:55 +00:00 • committed by Greg Kroah-Hartman

parent aee1f94dab

commit 74658868da

1 changed files with 140 additions and 26 deletions

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drivers/tty/serial/qcom_geni_serial.c

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