[U-Boot] [PATCH 01/21] Define new system_restart() and emergency_restart()

[Graeme Russ]

On Tue, Mar 8, 2011 at 9:10 AM, Mike Frysinger <vapier at 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)?

Regards,

Graeme