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If no_console_suspend is specified, on suspend the 8250 console driver uses a scratch register (UART_SCR) to store a special canary value. This is used during the resume path to identify a printk() call before the driver's own ->resume() callback. In this case, serial8250_console_restore() is called to quickly re-init the 8250 for console printing. See commit4516d50aab("serial: 8250: Use canary to restart console after suspend") for the original motivation. Unfortunately, this canary workaround does not work in all cases (such as suspend to mem) because the scratch register will not reset. This has not been a real issue until now because it could simply lead to some garbage characters upon resume. However, with the introduction of console flow control it becomes a real problem because a failed suspend/resume detection when flow control is enabled leads to all characters hitting the flow control timeout. Workaround this issue by temporarily ignoring console flow control when the debug canary suspend/resume detection is active. Fixes:5e6dfb87b1("serial: 8250: Add support for console flow control") Signed-off-by: John Ogness <john.ogness@linutronix.de> Link: https://patch.msgid.link/20260707141032.5074-1-john.ogness@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>