On Monday, March 07, 2011 18:09:25 Graeme Russ wrote: > On Tue, Mar 8, 2011 at 9:10 AM, Mike Frysinger <vap...@gentoo.org> wrote: > > On Monday, March 07, 2011 16:56:31 Moffett, Kyle D wrote: > >> On Mar 07, 2011, at 16:40, Mike Frysinger wrote: > >> > On Monday, March 07, 2011 12:37:22 Kyle Moffett wrote: > >> >> + udelay(50000); > >> > > >> > this doesnt sit well with me. i dont see why this matters ... we dont > >> > have any delays today, and i dont think we should introduce any. > >> > >> Actually, several architectures had a printf()+udelay() already. (i386 > >> and ARM, IIRC). Since I was moving the printf() to common code I > >> figured I'd better move the udelay() as well. > >> > >> I believe they had comments to the effect of "This udelay() prevents > >> garbage on the serial console while rebooting", I would guess because it > >> gives the FIFO time to finish flushing. > > > > Blackfin specifically does not do this. personally, a half baked uart > > char is preferable to a (imo) useless hardcoded delay. i wonder if they > > picked a number that seems to work, or actually calculated it based on > > the slowest baud times the deepest fifo times the extra bits > > (parity/stop/etc...). i'd suspect the former which means this is even > > dumber. > > > >> I can move it back to the individual architectures if you'd like. > > > > if we cant agree to simply punt it, then yes, please do. or make it a > > config option so board porters can opt out, and default it to on for > > only the existing arches. > > Is there any way we could detect that the UART FIFO is empty and wait on > that condition (with a timeout in case the FIFO is never emptied)?
that would require extending the serial API to add a new func, have each serial driver implement (i'm pretty sure most serial devices out there expose a bit to poll such status), and then having the code call it. i'm not saying it cant be done, just outlining the requirements. although i vaguely recall that Wolfgang is against this sort of thing since it kind of goes against the KISS principle ... -mike
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