linux-kernel - [patch] snd hda suspend latency: shorten codec read

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Date:	Fri, 16 Nov 2007 13:58:24 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Mark Lord <lkml@....ca>, perex@...ex.cz,
	Takashi Iwai <tiwai@...e.de>
Cc:	Pavel Machek <pavel@....cz>, Mark Lord <liml@....ca>,
	Thomas Gleixner <tglx@...utronix.de>, len.brown@...el.com,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, linux-pm@...ts.linux-foundation.org,
	rjw@...k.pl, Len Brown <lenb@...nel.org>
Subject: [patch] snd hda suspend latency: shorten codec read


snd hda suspend latency goes down a second via the patch below.

	Ingo

------------->
Subject: snd hda suspend latency: shorten codec read
From: Ingo Molnar <mingo@...e.hu>

not sleeping for every codec read/write but doing a short udelay and
a conditional reschedule has cut suspend+resume latency by about 1
second on my T60.

Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
 sound/pci/hda/hda_intel.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Index: linux/sound/pci/hda/hda_intel.c
===================================================================
--- linux.orig/sound/pci/hda/hda_intel.c
+++ linux/sound/pci/hda/hda_intel.c
@@ -555,7 +555,8 @@ static unsigned int azx_rirb_get_respons
 		}
 		if (!chip->rirb.cmds)
 			return chip->rirb.res; /* the last value */
-		schedule_timeout_uninterruptible(1);
+		udelay(10);
+		cond_resched();
 	} while (time_after_eq(timeout, jiffies));
 
 	if (chip->msi) {
-
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