On Wed, May 30, 2018 at 5:50 AM, Johan Hovold <johan@xxxxxxxxxx> wrote: > Add support for controller runtime power management to serdev core. This > is needed to allow slave drivers to manage the runtime PM state of the > underlying serial controller when its driver, in turn, implements more > aggressive runtime power management (e.g. using autosuspend). > > For some applications, for example, where loss off initial data after a > remote-wakeup event is acceptable or where rx is not used at all, > aggressive serial controller runtime PM may be used without further > involvement of the slave driver. But when this is not the case, the > slave driver must be able to indicate when incoming data is expected in > order to avoid data loss. > > To facilitate the common case, where the serial controller power state > is active whenever the port is open (which is the case with just about > every serial driver), and where data loss is not acceptable and cannot > even be prevented by explicit controller runtime power management, an > RPM reference is taken in serdev open and put again at close. This > reference can later be balanced by any serdev driver which wants and/or > can handle aggressive controller runtime PM. > > Note that the .ignore_children flag is set for the serdev controller to > allow the underlying hardware to idle when no I/O is expected, regardless > of the slave device RPM state. > > Acked-by: Tony Lindgren <tony@xxxxxxxxxxx> > Reviewed-by: Sebastian Reichel <sebastian.reichel@xxxxxxxxxxxxxxx> > Signed-off-by: Johan Hovold <johan@xxxxxxxxxx> > --- > > Hi Rob and Greg, > > This is a resend of the serdev controller runtime PM patch, which you > haven't commented on yet (possibly due to the following extensive > discussions on how to generalise the aggressive OMAP serial runtime PM > implementation). > > This patch works with what we have today, regardless of how we end up > configuring the serial controller (active) runtime PM behaviour > (currently done through sysfs for OMAP), which is a separate issue. > > No changes in this resend, besides me adding Tony's and Sebastian's ack > and reviewed-by tags and dropping the second patch which only served as > an example of how to use this in a serdev driver. Acked-by: Rob Herring <robh@xxxxxxxxxx> Rob -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
