* Johan Hovold <johan@xxxxxxxxxx> [210923 12:50]:
> On Tue, Sep 21, 2021 at 01:33:44PM +0300, Tony Lindgren wrote:
> > +static int serial8250_prep_tx(struct uart_port *port)
> > +{
> > + struct uart_8250_port *up = up_to_u8250p(port);
> > + struct device *dev = up->port.dev;
> > + int err;
> > +
> > + if (!(up->capabilities & UART_CAP_RPM))
> > + return 0;
> > +
> > + if (!pm_runtime_suspended(dev)) {
> > + pm_runtime_mark_last_busy(dev);
> > + return 0;
> > + }
> > +
> > + err = pm_request_resume(dev);
> > + if (err < 0) {
> > + dev_warn(dev, "prep_tx wakeup failed: %d\n", err);
> > + return err;
> > + }
>
> How is this supposed to work without a runtime PM usage-counter
> increment? What's to prevent the port from suspending again while it's
> transmitting?
Hmm yeah we should at pm_runtime_get() and pm_runtime_put() to write()
unless serial8250_rpm_get() and serial8250_rpm_put() are doing it.
Or pair prep with finish and deal with the usage count there.
Regards,
Tony
