Messages in this thread | | | Date | Wed, 4 Oct 2023 20:44:36 +0200 | Subject | Re: [PATCH v12 1/1] serial: core: Start managing serial controllers to enable runtime PM | From | Maximilian Luz <> |
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On 10/4/23 12:01, Tony Lindgren wrote: > * Johan Hovold <johan@kernel.org> [231004 09:14]: >> On Wed, Oct 04, 2023 at 12:03:20PM +0300, Tony Lindgren wrote: >>> The serial port device and serdev device are siblings of the physical >>> serial port controller device as seen in the hierarcy printed out by >>> Maximilian. >> >> Yeah, and that's precisely the broken part. Keeping the serdev >> controller active is supposed to keep the serial controller active. Your >> serial core rework appears to have broken just that. > > Hmm OK good point, tx can currently have an extra delay if a serdev > device is active, and the serial port controller device is not active. > > So we can check for active port->dev instead of &port_dev->dev though > to know when when start_tx() is safe to do as below.
I can confirm that this works as well.
Thanks, Max
> 8< ----------------- > diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c > index 6207f0051f23d..defecc5b04422 100644 > --- a/drivers/tty/serial/serial_core.c > +++ b/drivers/tty/serial/serial_core.c > @@ -156,7 +156,7 @@ static void __uart_start(struct uart_state *state) > * enabled, serial_port_runtime_resume() calls start_tx() again > * after enabling the device. > */ > - if (pm_runtime_active(&port_dev->dev)) > + if (!pm_runtime_enabled(port->dev) || pm_runtime_active(port->dev)) > port->ops->start_tx(port); > pm_runtime_mark_last_busy(&port_dev->dev); > pm_runtime_put_autosuspend(&port_dev->dev); >
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