Subject: Re: [PATCH 4/4] Uartlite: speed up console output

From: Peter Korsgaard <[email-masked]>
Date: Wed, 31 Oct 2007 15:45:02 +0100

>>>>> "Grant" == Grant Likely <[email-masked]> writes:

Hi,

 Grant> From: Grant Likely <[email-masked]>
 Grant> Change the wait_tx routine to call cpu_relax() instead of udelay() to
 Grant> reduce console output latency and test for the TXFULL bit instead of
 Grant> TXEMPTY.  That way the FIFO doesn't need to by 100% flushed before
 Grant> writing the next character.

Sorry for the slow response - I had a misunderstanding with the
phone company, and I'm now without inet :/

Looks good to me. I gave it a quick spin to check the speed
difference:

Old:
[    0.453101] Freeing unused kernel memory: 52k init

New:
[    0.433686] Freeing unused kernel memory: 52k init

So it shaves off ~20ms (~4%) of bootup.

It ofcause means that the console routines return before the data is
actually transmitted on the wire, but I guess you have to screw
seriously up for the UART to die before emptying it's FIFO.

 Grant> Signed-off-by: Grant Likely <[email-masked]>

Acked-by: Peter Korsgaard <[email-masked]>

-- 
Bye, Peter Korsgaard