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ANDROID: usb: gadget: f_audio_source: disable the CPU C-states upon playback

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Due to the issue with the isoc transfers being interrupted
by the CPU going into the idle state, the C-states will be
disabled for the playback time.

Change-Id: If4e52673606923d7e33a1d1dbe0192b8ad24f78c
Signed-off-by: Konrad Leszczynski <konrad.leszczynski@intel.com>
Signed-off-by: Russ Weight <russell.h.weight@intel.com>
This commit is contained in:
Konrad Leszczynski
2016-02-24 10:47:12 +00:00
committed by Badhri Jagan Sridharan
parent 69a14c17de
commit 4f87851849
1 changed files with 11 additions and 0 deletions
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11
drivers/usb/gadget/function/f_audio_source.c
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@@ -17,6 +17,7 @@
#include <linux/device.h>
#include <linux/usb/audio.h>
#include <linux/wait.h>
#include <linux/pm_qos.h>
#include <sound/core.h>
#include <sound/initval.h>
#include <sound/pcm.h>
@@ -268,6 +269,8 @@ struct audio_dev {
/* number of frames sent since start_time */
s64 frames_sent;
struct audio_source_config *config;
/* for creating and issuing QoS requests */
struct pm_qos_request pm_qos;
};
static inline struct audio_dev *func_to_audio(struct usb_function *f)
@@ -740,6 +743,10 @@ static int audio_pcm_open(struct snd_pcm_substream *substream)
runtime->hw.channels_max = 2;
audio->substream = substream;
/* Add the QoS request and set the latency to 0 */
pm_qos_add_request(&audio->pm_qos, PM_QOS_CPU_DMA_LATENCY, 0);
return 0;
}
@@ -749,6 +756,10 @@ static int audio_pcm_close(struct snd_pcm_substream *substream)
unsigned long flags;
spin_lock_irqsave(&audio->lock, flags);
/* Remove the QoS request */
pm_qos_remove_request(&audio->pm_qos);
audio->substream = NULL;
spin_unlock_irqrestore(&audio->lock, flags);