63e20df1e5
The current code deals with the stream start / stop solely via line6_pcm_acquire() and line6_pcm_release(). This was (supposedly) intended to avoid the races, but it doesn't work as expected. The concurrent acquire and release calls can be performed without proper protections, thus this might result in memory corruption. Furthermore, we can't take a mutex to protect the whole function because it can be called from the PCM trigger callback that is an atomic context. Also spinlock isn't appropriate because the function allocates with kmalloc with GFP_KERNEL. That is, these function just lead to singular problems. This is an attempt to reduce the existing races. First off, separate both the stream buffer management and the stream URB management. The former is protected via a newly introduced state_mutex while the latter is protected via each line6_pcm_stream lock. Secondly, the stream state are now managed in opened and running bit flags of each line6_pcm_stream. Not only this a bit clearer than previous combined bit flags, this also gives a better abstraction. These rewrites allows us to make common hw_params and hw_free callbacks for both playback and capture directions. For the monitor and impulse operations, still line6_pcm_acquire() and line6_pcm_release() are used. They call internally the corresponding functions for both playback and capture streams with proper lock or mutex. Unlike the previous versions, these function don't take the bit masks but the only single type value. Also they are supposed to be applied only as duplex operations. Tested-by: Chris Rorvick <chris@rorvick.com> Signed-off-by: Takashi Iwai <tiwai@suse.de>
36 lines
1.1 KiB
C
36 lines
1.1 KiB
C
/*
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* Line 6 Linux USB driver
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*
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* Copyright (C) 2004-2010 Markus Grabner (grabner@icg.tugraz.at)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation, version 2.
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*
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*/
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#ifndef PLAYBACK_H
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#define PLAYBACK_H
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#include <sound/pcm.h>
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#include "driver.h"
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/*
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* When the TonePort is used with jack in full duplex mode and the outputs are
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* not connected, the software monitor produces an ugly noise since everything
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* written to the output buffer (i.e., the input signal) will be repeated in
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* the next period (sounds like a delay effect). As a workaround, the output
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* buffer is cleared after the data have been read, but there must be a better
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* solution. Until one is found, this workaround can be used to fix the
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* problem.
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*/
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#define USE_CLEAR_BUFFER_WORKAROUND 1
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extern struct snd_pcm_ops snd_line6_playback_ops;
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extern int line6_create_audio_out_urbs(struct snd_line6_pcm *line6pcm);
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extern int line6_submit_audio_out_all_urbs(struct snd_line6_pcm *line6pcm);
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#endif
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