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authorTakashi Iwai <tiwai@suse.de>2017-02-07 08:05:46 +0100
committerTakashi Iwai <tiwai@suse.de>2017-02-10 10:21:42 +0100
commit8d48c0163d1ab0f56a18ebe9898a34ebcfdfaa1a (patch)
treef58c097b7d324f5a886f774bf394e7cfd28c3373 /sound/x86
parenta9ebdd0ef261fb9838af2821c09d165f6a14789b (diff)
downloadlinux-stericsson-8d48c0163d1ab0f56a18ebe9898a34ebcfdfaa1a.tar.gz
ALSA: x86: Allow single period PCM operation
This is an implementation of PCM streaming with only 1 period. Since the hardware requires the refresh of BDs after each BD processing finishes, we'd need at least two BDs. The trick is that both BDs point to the same content: the address of the PCM buffer head, and the whole buffer size. Then it loops over to the whole buffer again after it finished once. Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound/x86')
-rw-r--r--sound/x86/intel_hdmi_audio.c14
-rw-r--r--sound/x86/intel_hdmi_lpe_audio.h2
2 files changed, 13 insertions, 3 deletions
diff --git a/sound/x86/intel_hdmi_audio.c b/sound/x86/intel_hdmi_audio.c
index 73a662d20201..d2136498defe 100644
--- a/sound/x86/intel_hdmi_audio.c
+++ b/sound/x86/intel_hdmi_audio.c
@@ -822,6 +822,11 @@ static int had_prog_n(u32 aud_samp_freq, u32 *n_param,
*
* For nperiods < 4, the remaining BDs out of 4 are marked as invalid, so that
* the hardware skips those BDs in the loop.
+ *
+ * An exceptional setup is the case with nperiods=1. Since we have to update
+ * BDs after finishing one BD processing, we'd need at least two BDs, where
+ * both BDs point to the same content, the same address, the same size of the
+ * whole PCM buffer.
*/
#define AUD_BUF_ADDR(x) (AUD_BUF_A_ADDR + (x) * HAD_REG_WIDTH)
@@ -864,6 +869,8 @@ static void had_init_ringbuf(struct snd_pcm_substream *substream,
num_periods = runtime->periods;
intelhaddata->num_bds = min(num_periods, HAD_NUM_OF_RING_BUFS);
+ /* set the minimum 2 BDs for num_periods=1 */
+ intelhaddata->num_bds = max(intelhaddata->num_bds, 2U);
intelhaddata->period_bytes =
frames_to_bytes(runtime, runtime->period_size);
WARN_ON(intelhaddata->period_bytes & 0x3f);
@@ -873,7 +880,7 @@ static void had_init_ringbuf(struct snd_pcm_substream *substream,
intelhaddata->pcmbuf_filled = 0;
for (i = 0; i < HAD_NUM_OF_RING_BUFS; i++) {
- if (i < num_periods)
+ if (i < intelhaddata->num_bds)
had_prog_bd(substream, intelhaddata);
else /* invalidate the rest */
had_invalidate_bd(intelhaddata, i);
@@ -1255,7 +1262,10 @@ static snd_pcm_uframes_t had_pcm_pointer(struct snd_pcm_substream *substream)
len = had_process_ringbuf(substream, intelhaddata);
if (len < 0)
return SNDRV_PCM_POS_XRUN;
- return bytes_to_frames(substream->runtime, len);
+ len = bytes_to_frames(substream->runtime, len);
+ /* wrapping may happen when periods=1 */
+ len %= substream->runtime->buffer_size;
+ return len;
}
/*
diff --git a/sound/x86/intel_hdmi_lpe_audio.h b/sound/x86/intel_hdmi_lpe_audio.h
index 97bbca19333a..477e5153307c 100644
--- a/sound/x86/intel_hdmi_lpe_audio.h
+++ b/sound/x86/intel_hdmi_lpe_audio.h
@@ -31,7 +31,7 @@
#define HAD_MAX_BUFFER ((1024 * 1024 - 1) & ~0x3f)
#define HAD_DEFAULT_BUFFER (600 * 1024) /* default prealloc size */
#define HAD_MAX_PERIODS 256 /* arbitrary, but should suffice */
-#define HAD_MIN_PERIODS 2
+#define HAD_MIN_PERIODS 1
#define HAD_MAX_PERIOD_BYTES ((HAD_MAX_BUFFER / HAD_MIN_PERIODS) & ~0x3f)
#define HAD_MIN_PERIOD_BYTES 1024 /* might be smaller */
#define HAD_FIFO_SIZE 0 /* fifo not being used */