ALSA: emu10k1 - delay the PCM interrupts (add pcm_irq_delay parameter)

With some hardware combinations, the PCM interrupts are acknowledged
before the period boundary from the emu10k1 chip. The midlevel PCM code
gets confused and the playback stream is interrupted.

It seems that the interrupt processing shift by 2 samples is enough
to fix this issue. This default value does not harm other,
non-affected hardware.

More information: Kernel bugzilla bug#16300

[A copmile warning fixed by tiwai]

Signed-off-by: Jaroslav Kysela <perex@perex.cz>
Cc: <stable@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 26 insertions, 4 deletions

diff --git a/sound/pci/emu10k1/emupcm.c b/sound/pci/emu10k1/emupcm.c
index 55b83ef73c63..622bace148e3 100644
--- a/sound/pci/emu10k1/emupcm.c
+++ b/sound/pci/emu10k1/emupcm.c
@@ -332,7 +332,7 @@ static void snd_emu10k1_pcm_init_voice(struct snd_emu10k1 *emu,
                 evoice->epcm->ccca_start_addr = start_addr + ccis;
                 if (extra) {
                         start_addr += ccis;
-                        end_addr += ccis;
+                        end_addr += ccis + emu->delay_pcm_irq;
                 }
                 if (stereo && !extra) {
                         snd_emu10k1_ptr_write(emu, CPF, voice, CPF_STEREO_MASK);
@@ -360,7 +360,9 @@ static void snd_emu10k1_pcm_init_voice(struct snd_emu10k1 *emu,
         /* Assumption that PT is already 0 so no harm overwriting */
         snd_emu10k1_ptr_write(emu, PTRX, voice, (send_amount[0] << 8) | send_amount[1]);
         snd_emu10k1_ptr_write(emu, DSL, voice, end_addr | (send_amount[3] << 24));
-        snd_emu10k1_ptr_write(emu, PSST, voice, start_addr | (send_amount[2] << 24));
+        snd_emu10k1_ptr_write(emu, PSST, voice,
+                        (start_addr + (extra ? emu->delay_pcm_irq : 0)) |
+                        (send_amount[2] << 24));
         if (emu->card_capabilities->emu_model)
                 pitch_target = PITCH_48000; /* Disable interpolators on emu1010 card */
         else 
@@ -732,6 +734,23 @@ static void snd_emu10k1_playback_stop_voice(struct snd_emu10k1 *emu, struct snd_
         snd_emu10k1_ptr_write(emu, IP, voice, 0);
 }
 
+static inline void snd_emu10k1_playback_mangle_extra(struct snd_emu10k1 *emu,
+                struct snd_emu10k1_pcm *epcm,
+                struct snd_pcm_substream *substream,
+                struct snd_pcm_runtime *runtime)
+{
+        unsigned int ptr, period_pos;
+
+        /* try to sychronize the current position for the interrupt
+           source voice */
+        period_pos = runtime->status->hw_ptr - runtime->hw_ptr_interrupt;
+        period_pos %= runtime->period_size;
+        ptr = snd_emu10k1_ptr_read(emu, CCCA, epcm->extra->number);
+        ptr &= ~0x00ffffff;
+        ptr |= epcm->ccca_start_addr + period_pos;
+        snd_emu10k1_ptr_write(emu, CCCA, epcm->extra->number, ptr);
+}
+
 static int snd_emu10k1_playback_trigger(struct snd_pcm_substream *substream,
                                         int cmd)
 {
@@ -753,6 +772,8 @@ static int snd_emu10k1_playback_trigger(struct snd_pcm_substream *substream,
                 /* follow thru */
         case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
         case SNDRV_PCM_TRIGGER_RESUME:
+                if (cmd == SNDRV_PCM_TRIGGER_PAUSE_RELEASE)
+                        snd_emu10k1_playback_mangle_extra(emu, epcm, substream, runtime);
                 mix = &emu->pcm_mixer[substream->number];
                 snd_emu10k1_playback_prepare_voice(emu, epcm->voices[0], 1, 0, mix);
                 snd_emu10k1_playback_prepare_voice(emu, epcm->voices[1], 0, 0, mix);
@@ -869,8 +890,9 @@ static snd_pcm_uframes_t snd_emu10k1_playback_pointer(struct snd_pcm_substream *
 #endif
         /*
         printk(KERN_DEBUG
-               "ptr = 0x%x, buffer_size = 0x%x, period_size = 0x%x\n",
-               ptr, runtime->buffer_size, runtime->period_size);
+               "ptr = 0x%lx, buffer_size = 0x%lx, period_size = 0x%lx\n",
+               (long)ptr, (long)runtime->buffer_size,
+               (long)runtime->period_size);
         */
         return ptr;
 }