On Mon, Nov 15, 2021 at 10:42:03AM +0200, Tony Lindgren wrote:
> From: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
>
> Since we now have runtime PM calls in serial_core.c the individual
> drivers do not need them anymore for the struct uart_ops related
> functions.
>
> Remove runtime PM calls in 8250 driver. This still leaves the flag for
> UART_CAP_RPM for serial8250_rpm_get_tx(), serial8250_rpm_put_tx() and
> serial8250_wakeup() to manage the reference count for serial TX.
>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> [tony@xxxxxxxxxxx: updated to remove the exported functions too]
> Signed-off-by: Tony Lindgren <tony@xxxxxxxxxxx>
> @@ -1477,8 +1459,11 @@ static enum hrtimer_restart serial8250_em485_handle_stop_tx(struct hrtimer *t)
> stop_tx_timer);
> struct uart_8250_port *p = em485->port;
> unsigned long flags;
> + int err;
>
> - serial8250_rpm_get(p);
> + err = pm_runtime_resume_and_get(p->port.dev);
This also won't work as this function is called on timer expiry; you
cannot do a synchronous resume here.
> + if (err < 0)
> + goto out_rpm_err;
> spin_lock_irqsave(&p->port.lock, flags);
> if (em485->active_timer == &em485->stop_tx_timer) {
> p->rs485_stop_tx(p);
> @@ -1486,8 +1471,9 @@ static enum hrtimer_restart serial8250_em485_handle_stop_tx(struct hrtimer *t)
> em485->tx_stopped = true;
> }
> spin_unlock_irqrestore(&p->port.lock, flags);
> - serial8250_rpm_put(p);
> -
> + pm_runtime_mark_last_busy(p->port.dev);
> + pm_runtime_put_autosuspend(p->port.dev);
> +out_rpm_err:
> return HRTIMER_NORESTART;
> }
> void serial8250_read_char(struct uart_8250_port *up, unsigned char lsr)
> @@ -1984,15 +1966,11 @@ static unsigned int serial8250_tx_empty(struct uart_port *port)
> unsigned long flags;
> unsigned int lsr;
>
> - serial8250_rpm_get(up);
> -
> spin_lock_irqsave(&port->lock, flags);
> lsr = serial_port_in(port, UART_LSR);
> up->lsr_saved_flags |= lsr & LSR_SAVE_FLAGS;
> spin_unlock_irqrestore(&port->lock, flags);
>
> - serial8250_rpm_put(up);
> -
> return (lsr & BOTH_EMPTY) == BOTH_EMPTY ? TIOCSER_TEMT : 0;
> }
As I mentioned elsewhere, the corresponding get+put is missing in serial
core now.
> static void serial8250_put_poll_char(struct uart_port *port,
> unsigned char c)
> {
> unsigned int ier;
> struct uart_8250_port *up = up_to_u8250p(port);
>
> - serial8250_rpm_get(up);
> /*
> * First save the IER then disable the interrupts
> */
> @@ -2155,7 +2117,6 @@ static void serial8250_put_poll_char(struct uart_port *port,
> */
> wait_for_xmitr(up, BOTH_EMPTY);
> serial_port_out(port, UART_IER, ier);
> - serial8250_rpm_put(up);
> }
And this is a console callback; where is it guaranteed that the console
is never suspended?
Johan
