From: Milton Miller <miltonm@bga•com>
To: Alan Cox <alan@lxorguk•ukuu.org.uk>
Cc: linuxppc-dev list <linuxppc-dev@ozlabs•org>,
Christian Borntraeger <borntraeger@de•ibm.com>,
Joe Peterson <joe@skyrush•com>,
lkml <linux-kernel@vger•kernel.org>
Subject: Re: [PATCH 1/4] hvc_console: do not set low_latency
Date: Thu, 8 Jan 2009 07:25:14 -0600 [thread overview]
Message-ID: <455ca36e8b5778fd4c7218ef31fca07c@bga.com> (raw)
In-Reply-To: <20090108123619.3543719f@lxorguk.ukuu.org.uk>
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
next prev parent reply other threads:[~2009-01-08 13:18 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-01-08 5:18 [BUG] hvc_console WARN() on current upstream Benjamin Herrenschmidt
2009-01-08 7:57 ` Christian Borntraeger
2009-01-08 8:42 ` Benjamin Herrenschmidt
2009-01-08 11:11 ` Alan Cox
2009-01-08 12:12 ` [PATCH 0/5] hvc_console updates was " Milton Miller
2009-01-08 12:14 ` [PATCH 4/4] hvc_console: comment mb and make it an smp_ one Milton Miller
2009-01-08 12:14 ` [PATCH 3/4] hvc_console: free_irq only if request_irq was successful Milton Miller
2009-01-08 16:50 ` Christian Borntraeger
2009-01-08 12:14 ` [PATCH 1/4] hvc_console: do not set low_latency Milton Miller
2009-01-08 12:36 ` Alan Cox
2009-01-08 13:25 ` Milton Miller [this message]
2009-01-13 9:04 ` Christian Borntraeger
2009-01-13 11:28 ` Christian Borntraeger
2009-01-13 11:35 ` Hendrik Brueckner
2009-01-13 16:03 ` Milton Miller
2009-01-13 21:04 ` Benjamin Herrenschmidt
2009-01-15 9:15 ` [PATCH 1/4 v2] hvc_console: remove tty->low_latency Hendrik Brueckner
2009-01-15 9:17 ` Christian Borntraeger
2009-01-08 12:14 ` [PATCH 2/4] hvc_console: use kzalloc Milton Miller
2009-01-08 20:36 ` [BUG] hvc_console WARN() on current upstream Benjamin Herrenschmidt
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