From 76fb87894828756e069a43ce55f775a6c893a53d Mon Sep 17 00:00:00 2001 From: Clemens Ladisch Date: Sun, 13 May 2012 22:03:09 +0200 Subject: ALSA: firewire-lib: taskletize the snd_pcm_period_elapsed() call The following patch might introduce this call chain: PCM .pointer callback + fw_iso_context_flush_completions + packet callback + snd_pcm_period_elapsed + PCM .pointer callback Recursive calls to the pointer callback are not possible due to the PCM group locking, so avoid this by moving the period notification into a separate tasklet. Signed-off-by: Clemens Ladisch Signed-off-by: Takashi Iwai --- sound/firewire/amdtp.c | 29 ++++++++++++++++++++++++++++- 1 file changed, 28 insertions(+), 1 deletion(-) (limited to 'sound/firewire/amdtp.c') diff --git a/sound/firewire/amdtp.c b/sound/firewire/amdtp.c index 87657dd..3284ee9 100644 --- a/sound/firewire/amdtp.c +++ b/sound/firewire/amdtp.c @@ -31,6 +31,8 @@ #define INTERRUPT_INTERVAL 16 #define QUEUE_LENGTH 48 +static void pcm_period_tasklet(unsigned long data); + /** * amdtp_out_stream_init - initialize an AMDTP output stream structure * @s: the AMDTP output stream to initialize @@ -47,6 +49,7 @@ int amdtp_out_stream_init(struct amdtp_out_stream *s, struct fw_unit *unit, s->flags = flags; s->context = ERR_PTR(-1); mutex_init(&s->mutex); + tasklet_init(&s->period_tasklet, pcm_period_tasklet, (unsigned long)s); s->packet_index = 0; return 0; @@ -164,6 +167,20 @@ void amdtp_out_stream_set_pcm_format(struct amdtp_out_stream *s, } EXPORT_SYMBOL(amdtp_out_stream_set_pcm_format); +/** + * amdtp_out_stream_pcm_prepare - prepare PCM device for running + * @s: the AMDTP output stream + * + * This function should be called from the PCM device's .prepare callback. + */ +void amdtp_out_stream_pcm_prepare(struct amdtp_out_stream *s) +{ + tasklet_kill(&s->period_tasklet); + s->pcm_buffer_pointer = 0; + s->pcm_period_pointer = 0; +} +EXPORT_SYMBOL(amdtp_out_stream_pcm_prepare); + static unsigned int calculate_data_blocks(struct amdtp_out_stream *s) { unsigned int phase, data_blocks; @@ -376,11 +393,20 @@ static void queue_out_packet(struct amdtp_out_stream *s, unsigned int cycle) s->pcm_period_pointer += data_blocks; if (s->pcm_period_pointer >= pcm->runtime->period_size) { s->pcm_period_pointer -= pcm->runtime->period_size; - snd_pcm_period_elapsed(pcm); + tasklet_hi_schedule(&s->period_tasklet); } } } +static void pcm_period_tasklet(unsigned long data) +{ + struct amdtp_out_stream *s = (void *)data; + struct snd_pcm_substream *pcm = ACCESS_ONCE(s->pcm); + + if (pcm) + snd_pcm_period_elapsed(pcm); +} + static void out_packet_callback(struct fw_iso_context *context, u32 cycle, size_t header_length, void *header, void *data) { @@ -532,6 +558,7 @@ void amdtp_out_stream_stop(struct amdtp_out_stream *s) return; } + tasklet_kill(&s->period_tasklet); fw_iso_context_stop(s->context); fw_iso_context_destroy(s->context); s->context = ERR_PTR(-1); -- cgit v1.1