From 4c08f6be639a0705673533d822a7d6df6b8a3715 Mon Sep 17 00:00:00 2001
From: Simon Farnsworth <simon.farnsworth@onelan.co.uk>
Date: Mon, 10 Dec 2012 08:35:09 -0300
Subject: [PATCH] --- yaml --- r: 357180 b: refs/heads/master c:
 87739868944919beb4e6b3860c74355a114a54a1 h: refs/heads/master v: v3

---
 [refs]                                          |  2 +-
 trunk/drivers/media/pci/saa7134/saa7134-video.c | 13 +++++++++++++
 trunk/drivers/media/pci/saa7134/saa7134.h       |  2 ++
 3 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index 5611f58e3868..bffdacd797a9 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: e8d4237325a475b02594d1fd85bb67983f7d57b9
+refs/heads/master: 87739868944919beb4e6b3860c74355a114a54a1
diff --git a/trunk/drivers/media/pci/saa7134/saa7134-video.c b/trunk/drivers/media/pci/saa7134/saa7134-video.c
index 3abf52711e13..7c503fb68526 100644
--- a/trunk/drivers/media/pci/saa7134/saa7134-video.c
+++ b/trunk/drivers/media/pci/saa7134/saa7134-video.c
@@ -2248,6 +2248,17 @@ static int saa7134_streamon(struct file *file, void *priv,
 	if (!res_get(dev, fh, res))
 		return -EBUSY;
 
+	/* The SAA7134 has a 1K FIFO; the datasheet suggests that when
+	 * configured conservatively, there's 22 usec of buffering for video.
+	 * We therefore request a DMA latency of 20 usec, giving us 2 usec of
+	 * margin in case the FIFO is configured differently to the datasheet.
+	 * Unfortunately, I lack register-level documentation to check the
+	 * Linux FIFO setup and confirm the perfect value.
+	 */
+	pm_qos_add_request(&fh->qos_request,
+			   PM_QOS_CPU_DMA_LATENCY,
+			   20);
+
 	return videobuf_streamon(saa7134_queue(fh));
 }
 
@@ -2259,6 +2270,8 @@ static int saa7134_streamoff(struct file *file, void *priv,
 	struct saa7134_dev *dev = fh->dev;
 	int res = saa7134_resource(fh);
 
+	pm_qos_remove_request(&fh->qos_request);
+
 	err = videobuf_streamoff(saa7134_queue(fh));
 	if (err < 0)
 		return err;
diff --git a/trunk/drivers/media/pci/saa7134/saa7134.h b/trunk/drivers/media/pci/saa7134/saa7134.h
index c24b6512bd8f..0a3feaa8589b 100644
--- a/trunk/drivers/media/pci/saa7134/saa7134.h
+++ b/trunk/drivers/media/pci/saa7134/saa7134.h
@@ -29,6 +29,7 @@
 #include <linux/notifier.h>
 #include <linux/delay.h>
 #include <linux/mutex.h>
+#include <linux/pm_qos.h>
 
 #include <asm/io.h>
 
@@ -469,6 +470,7 @@ struct saa7134_fh {
 	enum v4l2_buf_type         type;
 	unsigned int               resources;
 	enum v4l2_priority	   prio;
+	struct pm_qos_request	   qos_request;
 
 	/* video overlay */
 	struct v4l2_window         win;