Re: [PATCH v1 0/2] serial: 8250_port: Update runtime PM flow

[Greg Kroah-Hartman]

On Fri, Aug 14, 2026 at 01:16:28PM +0200, Andy Shevchenko wrote:
> There are two changes, one is a straightforward drop of the duplicate
> runtime PM call (which is idempotent and hence it's harmless to call,
> but practically no need to do so) and the other addresses long standing
> problem with potentially sleeping PM calls on some system in IRQ context.
> Also the latter might lead to unneeded resume-suspend cycle when IRQ is
> shared and interrupt is not ours. This mini-series to update runtime
> PM flow to make sure this won't happen.
> 
> Andy Shevchenko (2):
>   serial: 8250_port: Remove redundant pm_runtime_mark_last_busy() call
>   serial: 8250_port: properly handle runtime PM in IRQ
> 
>  drivers/tty/serial/8250/8250_port.c | 16 ++++++++++++----
>  1 file changed, 12 insertions(+), 4 deletions(-)
> 
> -- 
> 2.50.1
> 
> 

  CC      drivers/tty/serial/8250/8250_port.o
drivers/tty/serial/8250/8250_port.c: In function ‘serial8250_default_handle_irq’:
drivers/tty/serial/8250/8250_port.c:1897:32: error: unused variable ‘up’ [-Werror=unused-variable]
 1897 |         struct uart_8250_port *up = up_to_u8250p(port);
      |                                ^~
cc1: all warnings being treated as errors

:(