Re: [PATCH tty 1/1] serial: 8250: Change console_msr_work to IRQ_WORK_LAZY

[Jon Hunter <jonathanh@nvidia.com>]

On 28/08/2026 16:58, John Ogness wrote:
> For some platforms it is a problem to queue irq_work when entering
> cpuidle states. Since irq_work is used for deferred MSR handling,
> any atomic console printing when entering cpuidle states can lead
> to the affected hardware hanging. Tegra20 and Tegra30 are examples
> of such platforms. Avoiding raising the irq_work IRQ has shown to
> circumvent the problem.
> 
> Change the console_msr_work to be IRQ_WORK_LAZY, thus not raising
> an IRQ upon irq_work queuing. The irq_work is then handled on the
> next interrupt (worst case, kernel tick).
> 
> Link: https://lore.kernel.org/lkml/f3757a75-0ba1-4558-bf57-f19ab7e59a4c@nvidia.com
> Fixes: d3539347022a ("serial: 8250: Switch to nbcon console, take 2")
> Signed-off-by: John Ogness <john.ogness@linutronix.de>
> ---
>   drivers/tty/serial/8250/8250_port.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
> index 38fa45e74a37a..1acb73e45f8a0 100644
> --- a/drivers/tty/serial/8250/8250_port.c
> +++ b/drivers/tty/serial/8250/8250_port.c
> @@ -3597,7 +3597,7 @@ int serial8250_console_setup(struct uart_port *port, char *options, bool probe)
>   
>   	up->console_line_ended = true;
>   	up->console_msr_work_allow = true;
> -	init_irq_work(&up->console_msr_work, console_msr_handler);
> +	up->console_msr_work = IRQ_WORK_INIT_LAZY(console_msr_handler);
>   
>   	if (options)
>   		uart_parse_options(options, &baud, &parity, &bits, &flow);


FWIW ...

Tested-by: Jon Hunter <jonathanh@nvidia.com>

Thanks!
Jon

-- 
nvpublic