@@ -191,14 +191,13 @@ int amdtp_stream_add_pcm_hw_constraints(struct amdtp_stream *s,
unsigned int maximum_usec_per_period;
int err;
- hw->info = SNDRV_PCM_INFO_BATCH |
- SNDRV_PCM_INFO_BLOCK_TRANSFER |
+ hw->info = SNDRV_PCM_INFO_BLOCK_TRANSFER |
SNDRV_PCM_INFO_INTERLEAVED |
SNDRV_PCM_INFO_JOINT_DUPLEX |
SNDRV_PCM_INFO_MMAP |
- SNDRV_PCM_INFO_MMAP_VALID;
+ SNDRV_PCM_INFO_MMAP_VALID |
+ SNDRV_PCM_INFO_NO_PERIOD_WAKEUP;
- /* SNDRV_PCM_INFO_BATCH */
hw->periods_min = 2;
hw->periods_max = UINT_MAX;
@@ -503,7 +502,12 @@ static void update_pcm_pointers(struct amdtp_stream *s,
s->pcm_period_pointer += frames;
if (s->pcm_period_pointer >= pcm->runtime->period_size) {
s->pcm_period_pointer -= pcm->runtime->period_size;
- queue_work(system_highpri_wq, &s->period_work);
+
+ // The program in user process should periodically check the status of intermediate
+ // buffer associated to PCM substream to process PCM frames in the buffer, instead
+ // of receiving notification of period elapsed by poll wait.
+ if (!pcm->runtime->no_period_wakeup)
+ queue_work(system_highpri_wq, &s->period_work);
}
}
@@ -949,6 +953,7 @@ static void process_rx_packets(struct fw_iso_context *context, u32 tstamp, size_
unsigned int event_count = s->ctx_data.rx.event_count;
unsigned int pkt_header_length;
unsigned int packets;
+ bool need_hw_irq;
int i;
if (s->packet_index < 0)
@@ -968,6 +973,16 @@ static void process_rx_packets(struct fw_iso_context *context, u32 tstamp, size_
else
pkt_header_length = 0;
+ if (s == d->irq_target) {
+ // At NO_PERIOD_WAKEUP mode, the packets for all IT/IR contexts are processed by
+ // the tasks of user process operating ALSA PCM character device by calling ioctl(2)
+ // with some requests, instead of scheduled hardware IRQ of an IT context.
+ struct snd_pcm_substream *pcm = READ_ONCE(s->pcm);
+ need_hw_irq = !pcm || !pcm->runtime->no_period_wakeup;
+ } else {
+ need_hw_irq = false;
+ }
+
for (i = 0; i < packets; ++i) {
const struct pkt_desc *desc = s->pkt_descs + i;
struct {
@@ -984,7 +999,7 @@ static void process_rx_packets(struct fw_iso_context *context, u32 tstamp, size_
event_count += desc->data_blocks;
if (event_count >= events_per_period) {
event_count -= events_per_period;
- sched_irq = true;
+ sched_irq = need_hw_irq;
}
}
Drivers of ALSA firewire stack can process packets for IT/IR context in process context when the process operates ALSA PCM character device by calling ioctl(2) with some requests. The ioctl requests are: * SNDRV_PCM_IOCTL_HWSYNC * SNDRV_PCM_IOCTL_SYNC_PTR * SNDRV_PCM_IOCTL_REWIND * SNDRV_PCM_IOCTL_FORWARD * SNDRV_PCM_IOCTL_WRITEI_FRAMES * SNDRV_PCM_IOCTL_READI_FRAMES * SNDRV_PCM_IOCTL_WRITEN_FRAMES * SNDRV_PCM_IOCTL_READN_FRAMES This means that general application can process PCM frames apart from hardware IRQ invocation, even if they are programmed by either IRQ-based scheduling model or Timer-based scheduling model. This commit add support for Timer-based scheduling model by allowing PCM runtime to suppress both process wakeup per period and scheduling hardware IRQ. SNDRV_PCM_INFO_BATCH is obsoleted since ALSA IEC 61883-1/6 packet streaming engine can report the number of transferred PCM frames within PCM period boundary. The granularity equals to SYT_INTERVAL in blocking transmission. In non-blocking transmission, it doesn't equal to SYT_INTERVAL but doesn't exceed. This patch is tested with PulseAudio, and --sched-model option of axfer with fix against the issue reported at: * https://lore.kernel.org/alsa-devel/687f9871-7484-1370-04d1-9c968e86f72b@linux.intel.com/#r Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp> --- sound/firewire/amdtp-stream.c | 27 +++++++++++++++++++++------ 1 file changed, 21 insertions(+), 6 deletions(-)