From 13a988396cab68e6c6afd33e461a9e52ce23ff63 Mon Sep 17 00:00:00 2001
From: Koro Chen <koro.chen@mediatek.com>
Date: Wed, 13 May 2015 22:39:03 +0800
Subject: [PATCH] ALSA: pcm: Modify double acknowledged interrupts check
 condition

Currently in snd_pcm_update_hw_ptr0 during interrupt,
we consider there were double acknowledged interrupts when:
1. HW reported pointer is smaller than expected, and
2. Time from last update time (hdelta) is over half a buffer time.

However, when HW reported pointer is only a few bytes smaller than
expected, and when hdelta is just a little larger than half a buffer time
(e.g. ping-pong buffer), it wrongly treats this IRQ as double acknowledged.

The condition #2 uses jiffies, but jiffies is not high resolution
since it is integer. We should consider jiffies inaccuracy.

Signed-off-by: Koro Chen <koro.chen@mediatek.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
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