Messages in this thread | | | Date | Mon, 14 Jan 2008 10:04:59 +0100 | From | Pavel Machek <> | Subject | Re: [PATCH: 2/2] [SERIAL] avoid stalling suspend if serial port won't drain |
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On Mon 2008-01-14 00:29:12, Russell King wrote: > On Fri, Jan 11, 2008 at 10:17:21AM +0000, Pavel Machek wrote: > > On Tue 2008-01-08 11:57:03, Russell King wrote: > > > + if (!tries) > > > + printk(KERN_ERR "%s%s%s%d: Unable to drain transmitter\n", > > > + port->dev ? port->dev->bus_id : "", > > > + port->dev ? ": " : "", > > > + drv->dev_name, port->line); > > > > > > ops->shutdown(port); > > > } > > > > > > > Is printk() enough for 'we've just lost your data' condition? Maybe we > > should abort suspend if we can't drain fifo? > > That would mean that a port set for hardware flow control, with hardware > implemented flow control, has CTS deasserted, you'll never suspend.
Yep.
> If you're suspending because your battery is almost dead what would you > prefer - the system being prevented from suspending and losing complete > power unexpectedly, resulting in complete data loss, or losing the > characters in the serial port and suspending? > > Which is the lesser of two evils?
Not sure, but there's third option -- correct but more work. What about saving/restoring fifo state? That will not stall suspend, nor will loose data. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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