[PATCH 0/2] serial: qcom-geni: Convert console to nbcon and handle RX overflow

[Bjorn Andersson]

The Qualcomm GENI UART uses independent sequencers. The main
sequencer handles console TX and the secondary sequencer handles
FIFO RX.

The legacy console writer disables both interrupt domains while it
performs a potentially long polled M-side transfer. Besides blocking
printk callers for UART wire time, this leaves the small S-side FIFO
unserviced and can lose interactive console input through FIFO overrun.

This two-patch series converts the console to nbcon, then keep FIFO RX
active while console output is in progress.

Patch 1 adds nbcon threaded and atomic writers. It uses bounded
32-byte M-side commands so higher-priority atomic output can take over
without waiting for a complete printk record. Atomic output may cancel
normal M-side TX. The driver restarts queued TTY output with irq_work,
honors flow control, and prevents deferred work from accessing a shut
down or removed port.

Patch 2 keeps FIFO RX on the secondary sequencer and drains it while
the threaded writer refills console TX. It also defers SysRq delivery
from this new receive context until the UART port lock is released.

Signed-off-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxxxxxxxx>
---
Bjorn Andersson (2):
      serial: qcom-geni: Convert console to nbcon
      serial: qcom-geni: Keep FIFO RX active during console TX

 drivers/tty/serial/qcom_geni_serial.c | 272 ++++++++++++++++++++++++++--------
 1 file changed, 212 insertions(+), 60 deletions(-)
---
base-commit: 78bc8af4affb9a732504eb22eeac7d1e50883853
change-id: 20260723-qcom-geni-nbcon-55816a833d8c

Best regards,
--  
Bjorn Andersson <bjorn.andersson@xxxxxxxxxxxxxxxx>