>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. I hope it's clear explanation. -- 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
