ASoC: imx-ssi: Use a hrtimer in FIQ mode

Using a regular timer results in poll times < 1 jiffie with small
buffers, so we loaded the timer with the actual jiffie value. We can
be more accurate using a hrtimer. Also, we have to call
snd_pcm_period_elapsed after playing period_bytes and not
runtime->period_size (which is in samples and not in bytes).

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

1 files changed, 21 insertions, 24 deletions

diff --git a/sound/soc/imx/imx-pcm-fiq.c b/sound/soc/imx/imx-pcm-fiq.c
index d9cb9849b03..64df813b9af 100644
--- a/sound/soc/imx/imx-pcm-fiq.c
+++ b/sound/soc/imx/imx-pcm-fiq.c
@@ -38,20 +38,17 @@ struct imx_pcm_runtime_data {
         unsigned long offset;
         unsigned long last_offset;
         unsigned long size;
-        struct timer_list timer;
-        int poll_time;
+        struct hrtimer hrt;
+        int poll_time_ns;
+        struct snd_pcm_substream *substream;
 };
 
-static inline void imx_ssi_set_next_poll(struct imx_pcm_runtime_data *iprtd)
+static enum hrtimer_restart snd_hrtimer_callback(struct hrtimer *hrt)
 {
-        iprtd->timer.expires = jiffies + iprtd->poll_time;
-}
-
-static void imx_ssi_timer_callback(unsigned long data)
-{
-        struct snd_pcm_substream *substream = (void *)data;
+        struct imx_pcm_runtime_data *iprtd =
+                container_of(hrt, struct imx_pcm_runtime_data, hrt);
+        struct snd_pcm_substream *substream = iprtd->substream;
         struct snd_pcm_runtime *runtime = substream->runtime;
-        struct imx_pcm_runtime_data *iprtd = runtime->private_data;
         struct pt_regs regs;
         unsigned long delta;
 
@@ -71,16 +68,14 @@ static void imx_ssi_timer_callback(unsigned long data)
 
         /* If we've transferred at least a period then report it and
          * reset our poll time */
-        if (delta >= runtime->period_size) {
+        if (delta >= iprtd->period) {
                 snd_pcm_period_elapsed(substream);
                 iprtd->last_offset = iprtd->offset;
-
-                imx_ssi_set_next_poll(iprtd);
         }
 
-        /* Restart the timer; if we didn't report we'll run on the next tick */
-        add_timer(&iprtd->timer);
+        hrtimer_forward_now(hrt, ns_to_ktime(iprtd->poll_time_ns));
 
+        return HRTIMER_RESTART;
 }
 
 static struct fiq_handler fh = {
@@ -98,8 +93,8 @@ static int snd_imx_pcm_hw_params(struct snd_pcm_substream *substream,
         iprtd->period = params_period_bytes(params) ;
         iprtd->offset = 0;
         iprtd->last_offset = 0;
-        iprtd->poll_time = HZ / (params_rate(params) / params_period_size(params));
-
+        iprtd->poll_time_ns = 1000000000 / params_rate(params) *
+                                params_period_size(params);
         snd_pcm_set_runtime_buffer(substream, &substream->dma_buffer);
 
         return 0;
@@ -134,8 +129,8 @@ static int snd_imx_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
         case SNDRV_PCM_TRIGGER_START:
         case SNDRV_PCM_TRIGGER_RESUME:
         case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
-                imx_ssi_set_next_poll(iprtd);
-                add_timer(&iprtd->timer);
+                hrtimer_start(&iprtd->hrt, ns_to_ktime(iprtd->poll_time_ns),
+                      HRTIMER_MODE_REL);
                 if (++fiq_enable == 1)
                         enable_fiq(imx_pcm_fiq);
 
@@ -144,7 +139,7 @@ static int snd_imx_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
         case SNDRV_PCM_TRIGGER_STOP:
         case SNDRV_PCM_TRIGGER_SUSPEND:
         case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
-                del_timer(&iprtd->timer);
+                hrtimer_cancel(&iprtd->hrt);
                 if (--fiq_enable == 0)
                         disable_fiq(imx_pcm_fiq);
 
@@ -193,9 +188,10 @@ static int snd_imx_open(struct snd_pcm_substream *substream)
         iprtd = kzalloc(sizeof(*iprtd), GFP_KERNEL);
         runtime->private_data = iprtd;
 
-        init_timer(&iprtd->timer);
-        iprtd->timer.data = (unsigned long)substream;
-        iprtd->timer.function = imx_ssi_timer_callback;
+        iprtd->substream = substream;
+
+        hrtimer_init(&iprtd->hrt, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+        iprtd->hrt.function = snd_hrtimer_callback;
 
         ret = snd_pcm_hw_constraint_integer(substream->runtime,
                         SNDRV_PCM_HW_PARAM_PERIODS);
@@ -211,7 +207,8 @@ static int snd_imx_close(struct snd_pcm_substream *substream)
         struct snd_pcm_runtime *runtime = substream->runtime;
         struct imx_pcm_runtime_data *iprtd = runtime->private_data;
 
-        del_timer_sync(&iprtd->timer);
+        hrtimer_cancel(&iprtd->hrt);
+
         kfree(iprtd);
 
         return 0;