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ALSA: firewire: Replace tasklet with work 

The tasklet is an old API that should be deprecated, usually can be
converted to another decent API.  In FireWire driver, a tasklet is
still used for offloading the AMDTP PCM stream handling.  It can be
achieved gracefully with a work queued, too.

This patch replaces the tasklet usage in firewire-lib driver with a
simple work.  The conversion is fairly straightforward but for the
in_interrupt() checks that are replaced with the check using the
current_work().

Note that in_interrupt() in amdtp_packet tracepoint is still kept as
is.  This is the place that is probed by both softirq of 1394 OHCI and
a user task of a PCM application, and the work handling is already
filtered in amdtp_domain_stream_pcm_pointer().

Tested-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Acked-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Link: https://lore.kernel.org/r/20200909163659.21708-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Iwai 2020-09-09 18:36:59 +02:00
parent 5554743d88
commit 2b3d2987d8
2 changed files with 14 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

25
sound/firewire/amdtp-stream.c
View File

@ -64,7 +64,7 @@
#define IT_PKT_HEADER_SIZE_CIP 8 // For 2 CIP header.
#define IT_PKT_HEADER_SIZE_NO_CIP 0 // Nothing.
static void pcm_period_tasklet(struct tasklet_struct *t);
static void pcm_period_work(struct work_struct *work);
/**
* amdtp_stream_init - initialize an AMDTP stream structure
@ -94,7 +94,7 @@ int amdtp_stream_init(struct amdtp_stream *s, struct fw_unit *unit,
s->flags = flags;
s->context = ERR_PTR(-1);
mutex_init(&s->mutex);
tasklet_setup(&s->period_tasklet, pcm_period_tasklet);
INIT_WORK(&s->period_work, pcm_period_work);
s->packet_index = 0;
init_waitqueue_head(&s->callback_wait);
@ -203,7 +203,7 @@ int amdtp_stream_add_pcm_hw_constraints(struct amdtp_stream *s,
// Linux driver for 1394 OHCI controller voluntarily flushes isoc
// context when total size of accumulated context header reaches
// PAGE_SIZE. This kicks tasklet for the isoc context and brings
// PAGE_SIZE. This kicks work for the isoc context and brings
// callback in the middle of scheduled interrupts.
// Although AMDTP streams in the same domain use the same events per
// IRQ, use the largest size of context header between IT/IR contexts.
@ -333,7 +333,7 @@ EXPORT_SYMBOL(amdtp_stream_get_max_payload);
*/
void amdtp_stream_pcm_prepare(struct amdtp_stream *s)
{
tasklet_kill(&s->period_tasklet);
cancel_work_sync(&s->period_work);
s->pcm_buffer_pointer = 0;
s->pcm_period_pointer = 0;
}
@ -437,13 +437,14 @@ 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;
tasklet_hi_schedule(&s->period_tasklet);
queue_work(system_highpri_wq, &s->period_work);
}
}
static void pcm_period_tasklet(struct tasklet_struct *t)
static void pcm_period_work(struct work_struct *work)
{
struct amdtp_stream *s = from_tasklet(s, t, period_tasklet);
struct amdtp_stream *s = container_of(work, struct amdtp_stream,
period_work);
struct snd_pcm_substream *pcm = READ_ONCE(s->pcm);
if (pcm)
@ -794,7 +795,7 @@ static void generate_pkt_descs(struct amdtp_stream *s, struct pkt_desc *descs,
static inline void cancel_stream(struct amdtp_stream *s)
{
s->packet_index = -1;
if (in_interrupt())
if (current_work() == &s->period_work)
amdtp_stream_pcm_abort(s);
WRITE_ONCE(s->pcm_buffer_pointer, SNDRV_PCM_POS_XRUN);
}
@ -1184,7 +1185,7 @@ unsigned long amdtp_domain_stream_pcm_pointer(struct amdtp_domain *d,
if (irq_target && amdtp_stream_running(irq_target)) {
// This function is called in software IRQ context of
// period_tasklet or process context.
// period_work or process context.
//
// When the software IRQ context was scheduled by software IRQ
// context of IT contexts, queued packets were already handled.
@ -1195,9 +1196,9 @@ unsigned long amdtp_domain_stream_pcm_pointer(struct amdtp_domain *d,
// immediately to keep better granularity of PCM pointer.
//
// Later, the process context will sometimes schedules software
// IRQ context of the period_tasklet. Then, no need to flush the
// IRQ context of the period_work. Then, no need to flush the
// queue by the same reason as described in the above
if (!in_interrupt()) {
if (current_work() != &s->period_work) {
// Queued packet should be processed without any kernel
// preemption to keep latency against bus cycle.
preempt_disable();
@ -1263,7 +1264,7 @@ static void amdtp_stream_stop(struct amdtp_stream *s)
return;
}
tasklet_kill(&s->period_tasklet);
cancel_work_sync(&s->period_work);
fw_iso_context_stop(s->context);
fw_iso_context_destroy(s->context);
s->context = ERR_PTR(-1);

2
sound/firewire/amdtp-stream.h
View File

@ -163,7 +163,7 @@ struct amdtp_stream {
/* For a PCM substream processing. */
struct snd_pcm_substream *pcm;
struct tasklet_struct period_tasklet;
struct work_struct period_work;
snd_pcm_uframes_t pcm_buffer_pointer;
unsigned int pcm_period_pointer;