[alsa-devel] [PATCH v2 2/2] ALSA - hda: Add support for link audio time reporting
Vinod Koul
vinod.koul at intel.com
Tue Jul 19 12:46:42 CEST 2016
From: Guneshwor Singh <guneshwor.o.singh at intel.com>
The HDA controller from SKL onwards support additional timestamp
reporting of the link time. The link time is read from HW
registers and converted to audio values.
Signed-off-by: Guneshwor Singh <guneshwor.o.singh at intel.com>
Signed-off-by: Hardik T Shah <hardik.t.shah at intel.com>
Signed-off-by: Vinod Koul <vinod.koul at intel.com>
---
sound/pci/hda/hda_controller.c | 195 ++++++++++++++++++++++++++++++++++++++++-
1 file changed, 194 insertions(+), 1 deletion(-)
diff --git a/sound/pci/hda/hda_controller.c b/sound/pci/hda/hda_controller.c
index 7e5e4c261e51..9ae69c000a13 100644
--- a/sound/pci/hda/hda_controller.c
+++ b/sound/pci/hda/hda_controller.c
@@ -27,6 +27,12 @@
#include <linux/module.h>
#include <linux/pm_runtime.h>
#include <linux/slab.h>
+
+#ifdef CONFIG_X86
+/* for art-tsc conversion */
+#include <asm/tsc.h>
+#endif
+
#include <sound/core.h>
#include <sound/initval.h>
#include "hda_controller.h"
@@ -337,12 +343,169 @@ static snd_pcm_uframes_t azx_pcm_pointer(struct snd_pcm_substream *substream)
azx_get_position(chip, azx_dev));
}
+/*
+ * azx_scale64: Scale base by mult/div while not overflowing sanely
+ *
+ * Derived from scale64_check_overflow in kernel/time/timekeeping.c
+ *
+ * The tmestamps for a 48Khz stream can overflow after (2^64/10^9)/48K which
+ * is about 384307 ie ~4.5 days.
+ *
+ * This scales the calculation so that overflow will happen but after 2^64 /
+ * 48000 secs, which is pretty large!
+ *
+ * In caln below:
+ * base may overflow, but since there isn’t any additional division
+ * performed on base it’s OK
+ * rem can’t overflow because both are 32-bit values
+ */
+
+#ifdef CONFIG_X86
+static u64 azx_scale64(u64 base, u32 num, u32 den)
+{
+ u64 rem;
+
+ rem = do_div(base, den);
+
+ base *= num;
+ rem *= num;
+
+ do_div(rem, den);
+
+ return base + rem;
+}
+
+static int azx_get_sync_time(ktime_t *device,
+ struct system_counterval_t *system, void *ctx)
+{
+ struct snd_pcm_substream *substream = (struct snd_pcm_substream *)ctx;
+ struct azx_dev *azx_dev = get_azx_dev(substream);
+ struct azx_pcm *apcm = snd_pcm_substream_chip(substream);
+ struct azx *chip = apcm->chip;
+ struct snd_pcm_runtime *runtime;
+ u64 ll_counter, ll_counter_l, ll_counter_h;
+ u64 tsc_counter, tsc_counter_l, tsc_counter_h;
+ u32 wallclk_ctr, wallclk_cycles;
+ bool direction;
+ u32 dma_select;
+ u32 timeout = 200;
+ u32 retry_count = 0;
+
+ runtime = substream->runtime;
+
+ if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
+ direction = 1;
+ else
+ direction = 0;
+
+ /* 0th stream tag is not used, so DMA ch 0 is for 1st stream tag */
+ do {
+ timeout = 100;
+ dma_select = (direction << GTSCC_CDMAS_DMA_DIR_SHIFT) |
+ (azx_dev->core.stream_tag - 1);
+ _snd_hdac_chip_write(l, azx_bus(chip), AZX_REG_GTSCC,
+ dma_select);
+ /* Enable the capture */
+ _snd_hdac_chip_write(l, azx_bus(chip), AZX_REG_GTSCC,
+ _snd_hdac_chip_read(l, azx_bus(chip),
+ AZX_REG_GTSCC) | GTSCC_TSCCI_MASK);
+
+ while (timeout) {
+ if (_snd_hdac_chip_read(l, azx_bus(chip),
+ AZX_REG_GTSCC) & GTSCC_TSCCD_MASK)
+ break;
+ timeout--;
+ }
+
+ if (!timeout) {
+ dev_err(chip->card->dev, "GTSCC capture Timedout!\n");
+ return -EIO;
+ }
+
+ /* Read wall clock counter */
+ wallclk_ctr = _snd_hdac_chip_read(l, azx_bus(chip),
+ AZX_REG_WALFCC);
+
+ /* Read TSC counter */
+ tsc_counter_l = _snd_hdac_chip_read(l, azx_bus(chip),
+ AZX_REG_TSCCL);
+ tsc_counter_h = _snd_hdac_chip_read(l, azx_bus(chip),
+ AZX_REG_TSCCU);
+
+ /* Read Link counter */
+ ll_counter_l = _snd_hdac_chip_read(l, azx_bus(chip),
+ AZX_REG_LLPCL);
+ ll_counter_h = _snd_hdac_chip_read(l, azx_bus(chip),
+ AZX_REG_LLPCU);
+
+ /* Ack: registers read done */
+ _snd_hdac_chip_write(l, azx_bus(chip),
+ AZX_REG_GTSCC,
+ (0x1 << GTSCC_TSCCD_SHIFT));
+
+ tsc_counter = (tsc_counter_h << TSCCU_CCU_SHIFT) |
+ tsc_counter_l;
+
+ ll_counter = (ll_counter_h << LLPC_CCU_SHIFT) | ll_counter_l;
+ wallclk_cycles = wallclk_ctr & WALFCC_CIF_MASK;
+
+ /*
+ * An error occurs near frame "rollover". The clocks in
+ * frame value indicates whether this error may have
+ * occurred. Here we use the value of 10 i.e.,
+ * HDA_MAX_CYCLE_OFFSET
+ */
+ if (wallclk_cycles < HDA_MAX_CYCLE_VALUE - HDA_MAX_CYCLE_OFFSET
+ && wallclk_cycles > HDA_MAX_CYCLE_OFFSET)
+ break;
+
+ /*
+ * Sleep before we read again, else we may again get
+ * value near to MAX_CYCLE. Try to sleep for different
+ * amount of time so we dont hit the same number again
+ */
+ udelay(retry_count++);
+
+ } while (retry_count != HDA_MAX_CYCLE_READ_RETRY);
+
+ if (retry_count == HDA_MAX_CYCLE_READ_RETRY) {
+ dev_err(chip->card->dev, "Error in WALFCC cycle count\n");
+ return -EIO;
+ }
+
+ *device = ns_to_ktime(azx_scale64(ll_counter,
+ NSEC_PER_SEC, runtime->rate));
+ *device = ktime_add_ns(*device, (wallclk_cycles * NSEC_PER_SEC) /
+ ((HDA_MAX_CYCLE_VALUE + 1) * runtime->rate));
+
+ *system = convert_art_to_tsc(tsc_counter);
+
+ return 0;
+}
+
+#else
+static int azx_get_sync_time(ktime_t *device,
+ struct system_counterval_t *system, void *ctx)
+{
+ return -ENXIO;
+}
+#endif
+
+static int azx_get_crosststamp(struct snd_pcm_substream *substream,
+ struct system_device_crosststamp *xtstamp)
+{
+ return get_device_system_crosststamp(azx_get_sync_time,
+ substream, NULL, xtstamp);
+}
+
static int azx_get_time_info(struct snd_pcm_substream *substream,
struct timespec *system_ts, struct timespec *audio_ts,
struct snd_pcm_audio_tstamp_config *audio_tstamp_config,
struct snd_pcm_audio_tstamp_report *audio_tstamp_report)
{
struct azx_dev *azx_dev = get_azx_dev(substream);
+ struct snd_pcm_runtime *runtime = substream->runtime;
+ struct system_device_crosststamp xtstamp;
u64 nsec;
if ((substream->runtime->hw.info & SNDRV_PCM_INFO_HAS_LINK_ATIME) &&
@@ -361,8 +524,38 @@ static int azx_get_time_info(struct snd_pcm_substream *substream,
audio_tstamp_report->accuracy_report = 1; /* rest of structure is valid */
audio_tstamp_report->accuracy = 42; /* 24 MHz WallClock == 42ns resolution */
- } else
+ } else if ((runtime->hw.info &
+ SNDRV_PCM_INFO_HAS_LINK_SYNCHRONIZED_ATIME) &&
+ (audio_tstamp_config->type_requested ==
+ SNDRV_PCM_AUDIO_TSTAMP_TYPE_LINK_SYNCHRONIZED)) {
+
+ azx_get_crosststamp(substream, &xtstamp);
+
+ switch (runtime->tstamp_type) {
+ case SNDRV_PCM_TSTAMP_TYPE_MONOTONIC:
+ return -EINVAL;
+
+ case SNDRV_PCM_TSTAMP_TYPE_MONOTONIC_RAW:
+ *system_ts = ktime_to_timespec(xtstamp.sys_monoraw);
+ break;
+
+ default:
+ *system_ts = ktime_to_timespec(xtstamp.sys_realtime);
+ break;
+
+ }
+
+ *audio_ts = ktime_to_timespec(xtstamp.device);
+
+ audio_tstamp_report->actual_type =
+ SNDRV_PCM_AUDIO_TSTAMP_TYPE_LINK_SYNCHRONIZED;
+ audio_tstamp_report->accuracy_report = 1;
+ /* 24 MHz WallClock == 42ns resolution */
+ audio_tstamp_report->accuracy = 42;
+
+ } else {
audio_tstamp_report->actual_type = SNDRV_PCM_AUDIO_TSTAMP_TYPE_DEFAULT;
+ }
return 0;
}
--
1.9.1
More information about the Alsa-devel
mailing list