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SubjectRe: [PATCH 1/4] hvc_console: do not set low_latency
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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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