Re: [PATCH 1/4] hvc_console: do not set low_latency
From: Milton Miller
Date: Thu Jan 08 2009 - 08:18:33 EST
On Jan 8, 2009, at 6:36 AM, Alan Cox wrote:
v2.6.16-rc1 via 33f0f88f1c51ae5c2d593d26960c760ea154c2e2
[PATCH] TTY layer buffering revamp
added this new api.
No - tty_flip_buffer_push is from 2.1.66 and with the same constraints
from the day it was added.
Yes but wrappers were added and this this and many ohter drivers were
converted to use them:
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;
a=commitdiff;h=33f0f88f1c51ae5c2d593d26960c760ea154c2e2
And they were slightly buggy leading to the buggy workaround.
Having the flag set for purely polled drivers will save delaying
the work when receiving input for 1 jiffie.
Index: work.git/drivers/char/hvc_console.c
===================================================================
--- work.git.orig/drivers/char/hvc_console.c 2009-01-08
03:01:24.000000000 -0600
+++ work.git/drivers/char/hvc_console.c 2009-01-08 03:01:51.000000000
-0600
@@ -318,7 +318,8 @@ static int hvc_open(struct tty_struct *t
} /* else count == 0 */
tty->driver_data = hp;
- tty->low_latency = 1; /* Makes flushes to ldisc synchronous. */
+ if (!hp->irq_requested)
+ tty->low_latency = 1; /* Makes flushes to ldisc synchronous. */
hp->tty = tty;
Looks good to me
Thanks, I guess that is an Ack?
milton
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