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-rw-r--r--sound/pci/echoaudio/echoaudio.c85
-rw-r--r--sound/pci/echoaudio/echoaudio.h8
2 files changed, 65 insertions, 28 deletions
diff --git a/sound/pci/echoaudio/echoaudio.c b/sound/pci/echoaudio/echoaudio.c
index c97928e7e56b..31449b7c51c6 100644
--- a/sound/pci/echoaudio/echoaudio.c
+++ b/sound/pci/echoaudio/echoaudio.c
@@ -2,6 +2,7 @@
/*
* ALSA driver for Echoaudio soundcards.
* Copyright (C) 2003-2004 Giuliano Pochini <pochini@shiny.it>
+ * Copyright (C) 2020 Mark Hills <mark@xwax.org>
*/
#include <linux/module.h>
@@ -590,7 +591,7 @@ static int init_engine(struct snd_pcm_substream *substream,
/* This stuff is used by the irq handler, so it must be
* initialized before chip->substream
*/
- chip->last_period[pipe_index] = 0;
+ pipe->last_period = 0;
pipe->last_counter = 0;
pipe->position = 0;
smp_wmb();
@@ -759,7 +760,7 @@ static int pcm_trigger(struct snd_pcm_substream *substream, int cmd)
pipe = chip->substream[i]->runtime->private_data;
switch (pipe->state) {
case PIPE_STATE_STOPPED:
- chip->last_period[i] = 0;
+ pipe->last_period = 0;
pipe->last_counter = 0;
pipe->position = 0;
*pipe->dma_counter = 0;
@@ -807,19 +808,26 @@ static snd_pcm_uframes_t pcm_pointer(struct snd_pcm_substream *substream)
{
struct snd_pcm_runtime *runtime = substream->runtime;
struct audiopipe *pipe = runtime->private_data;
- size_t cnt, bufsize, pos;
+ u32 counter, step;
- cnt = le32_to_cpu(*pipe->dma_counter);
- pipe->position += cnt - pipe->last_counter;
- pipe->last_counter = cnt;
- bufsize = substream->runtime->buffer_size;
- pos = bytes_to_frames(substream->runtime, pipe->position);
+ /*
+ * IRQ handling runs concurrently. Do not share tracking of
+ * counter with it, which would race or require locking
+ */
- while (pos >= bufsize) {
- pipe->position -= frames_to_bytes(substream->runtime, bufsize);
- pos -= bufsize;
- }
- return pos;
+ counter = le32_to_cpu(*pipe->dma_counter); /* presumed atomic */
+
+ step = counter - pipe->last_counter; /* handles wrapping */
+ pipe->last_counter = counter;
+
+ /* counter doesn't neccessarily wrap on a multiple of
+ * buffer_size, so can't derive the position; must
+ * accumulate */
+
+ pipe->position += step;
+ pipe->position %= frames_to_bytes(runtime, runtime->buffer_size); /* wrap */
+
+ return bytes_to_frames(runtime, pipe->position);
}
@@ -1782,14 +1790,43 @@ static const struct snd_kcontrol_new snd_echo_channels_info = {
/******************************************************************************
- IRQ Handler
+ IRQ Handling
******************************************************************************/
+/* Check if a period has elapsed since last interrupt
+ *
+ * Don't make any updates to state; PCM core handles this with the
+ * correct locks.
+ *
+ * \return true if a period has elapsed, otherwise false
+ */
+static bool period_has_elapsed(struct snd_pcm_substream *substream)
+{
+ struct snd_pcm_runtime *runtime = substream->runtime;
+ struct audiopipe *pipe = runtime->private_data;
+ u32 counter, step;
+ size_t period_bytes;
+
+ if (pipe->state != PIPE_STATE_STARTED)
+ return false;
+
+ period_bytes = frames_to_bytes(runtime, runtime->period_size);
+
+ counter = le32_to_cpu(*pipe->dma_counter); /* presumed atomic */
+
+ step = counter - pipe->last_period; /* handles wrapping */
+ step -= step % period_bytes; /* acknowledge whole periods only */
+
+ if (step == 0)
+ return false; /* haven't advanced a whole period yet */
+
+ pipe->last_period += step; /* used exclusively by us */
+ return true;
+}
static irqreturn_t snd_echo_interrupt(int irq, void *dev_id)
{
struct echoaudio *chip = dev_id;
- struct snd_pcm_substream *substream;
- int period, ss, st;
+ int ss, st;
spin_lock(&chip->lock);
st = service_irq(chip);
@@ -1800,17 +1837,13 @@ static irqreturn_t snd_echo_interrupt(int irq, void *dev_id)
/* The hardware doesn't tell us which substream caused the irq,
thus we have to check all running substreams. */
for (ss = 0; ss < DSP_MAXPIPES; ss++) {
+ struct snd_pcm_substream *substream;
+
substream = chip->substream[ss];
- if (substream && ((struct audiopipe *)substream->runtime->
- private_data)->state == PIPE_STATE_STARTED) {
- period = pcm_pointer(substream) /
- substream->runtime->period_size;
- if (period != chip->last_period[ss]) {
- chip->last_period[ss] = period;
- spin_unlock(&chip->lock);
- snd_pcm_period_elapsed(substream);
- spin_lock(&chip->lock);
- }
+ if (substream && period_has_elapsed(substream)) {
+ spin_unlock(&chip->lock);
+ snd_pcm_period_elapsed(substream);
+ spin_lock(&chip->lock);
}
}
spin_unlock(&chip->lock);
diff --git a/sound/pci/echoaudio/echoaudio.h b/sound/pci/echoaudio/echoaudio.h
index 6fd283e4e676..30c640931f1e 100644
--- a/sound/pci/echoaudio/echoaudio.h
+++ b/sound/pci/echoaudio/echoaudio.h
@@ -298,7 +298,12 @@ struct audiopipe {
* the current dma position
* (lower 32 bits only)
*/
- u32 last_counter; /* The last position, which is used
+ u32 last_period; /* Counter position last time a
+ * period elapsed
+ */
+ u32 last_counter; /* Used exclusively by pcm_pointer
+ * under PCM core locks.
+ * The last position, which is used
* to compute...
*/
u32 position; /* ...the number of bytes tranferred
@@ -332,7 +337,6 @@ struct audioformat {
struct echoaudio {
spinlock_t lock;
struct snd_pcm_substream *substream[DSP_MAXPIPES];
- int last_period[DSP_MAXPIPES];
struct mutex mode_mutex;
u16 num_digital_modes, digital_mode_list[6];
u16 num_clock_sources, clock_source_list[10];