On Wed, Nov 10, 2010 at 10:15:53AM +0200, Grzegorz.Sygieda@xxxxxxxxx wrote: > >On Tue, Nov 09, 2010 at 02:40:12PM -0800, Greg KH wrote: > >> On Tue, Nov 09, 2010 at 04:30:37PM +0100, Linus Walleij wrote: > >> > From: Grzegorz Sygieda <grzegorz.sygieda@xxxxxxxxx> > >> > > >> > This patch allows to control the pl011 clock using set_termios > >> > callback. Any positive baudrate passed enables clock, otherwise > >> > disables. This saves a lot of power on submicron designs since we > >> > can clock off and disable unused UARTs. > >> > >> That's nice, but it seems like an overload of what people > >> traditionally think of when it comes to baud rates. Why not just > >> power down ports that are not open instead? > > > >We already do. My question to Linus (in a previous message) is why this isn't sufficient. > > The main goal was to disable/enable clock while port open. This is > usefull for scenario, where some higher level driver wants to control > the power consumption (using set_termios). In the same time a > user-space app (eg. hciattach) is still bounded to the specific > /dev/tty* device associated with particular uart. From user POV device > is always open, and app does not have to respawn, and we can save > power. That is nice, but again, you are overloading a common interface (one defined by POSIX I think) to do something else at the same time. That might cause problems with some users that expect you to be able to use a baud rate of 0 :) I like the idea, but not the overloading, sorry. thanks, greg k-h -- 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
