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authorKarsten Wiese <annabellesgarden@yahoo.de>2005-10-18 14:31:07 +0200
committerJaroslav Kysela <perex@suse.cz>2005-11-04 13:19:00 +0100
commit4f550df58f4758ea023704b409830ad9c3b47771 (patch)
tree83f935c11032a2a4099e0996717482ddcce945ca
parentf0597a416dc44e3afe25090e9af9d42bad62547d (diff)
[ALSA] Reduce interrupt latency in sound/pci/via82xx.c
Modules: VIA82xx driver The change only affects the via823x kind of chips. Here the via8233_pcm_pointer_hw() function (named snd_via8233_pcm_pointer() before) needed to loop until a non zero position is red from the chip. Measurements have shown that more than 200 loops are typically needed on an Athlon64. As io-reads cost many cycles, those loops sum up huge. via8233_pcm_pointer_hw() runs either in interrupt or with interrupts disabled. So it introduces significant interrupt latency. The patch introduces a calculated position value hwptr_done, that is updated by the interrupt routine when a period is completed. It is only used, if the 823x chip returns a zero position, which can't be interpreted reliably. Further optimisation is applied on the 8233 chip's interrupt routine: Only the SGD_SHADOW is read, as it contains all infos needed. We ommit ~5 more register reads that way. Signed-off-by: Karsten Wiese <annabellesgarden@yahoo.de> Signed-off-by: Takashi Iwai <tiwai@suse.de>
-rw-r--r--sound/pci/via82xx.c170
1 files changed, 131 insertions, 39 deletions
diff --git a/sound/pci/via82xx.c b/sound/pci/via82xx.c
index 7d46bee828c7..eb35b446235c 100644
--- a/sound/pci/via82xx.c
+++ b/sound/pci/via82xx.c
@@ -41,6 +41,9 @@
* device for applications.
* - clean up the code, separate low-level initialization
* routines for each chipset.
+ *
+ * Sep. 26, 2005 Karsten Wiese <annabellesgarden@yahoo.de>
+ * - Optimize position calculation for the 823x chips.
*/
#include <sound/driver.h>
@@ -131,6 +134,7 @@ module_param(enable, int, 0444);
/* common offsets */
#define VIA_REG_OFFSET_STATUS 0x00 /* byte - channel status */
#define VIA_REG_STAT_ACTIVE 0x80 /* RO */
+#define VIA8233_SHADOW_STAT_ACTIVE 0x08 /* RO */
#define VIA_REG_STAT_PAUSED 0x40 /* RO */
#define VIA_REG_STAT_TRIGGER_QUEUED 0x08 /* RO */
#define VIA_REG_STAT_STOPPED 0x04 /* RWC */
@@ -329,6 +333,9 @@ struct via_dev {
unsigned int fragsize;
unsigned int bufsize;
unsigned int bufsize2;
+ int hwptr_done; /* processed frame position in the buffer */
+ int in_interrupt;
+ int shadow_shift;
};
@@ -395,8 +402,10 @@ struct _snd_via82xx {
};
static struct pci_device_id snd_via82xx_ids[] = {
- { 0x1106, 0x3058, PCI_ANY_ID, PCI_ANY_ID, 0, 0, TYPE_CARD_VIA686, }, /* 686A */
- { 0x1106, 0x3059, PCI_ANY_ID, PCI_ANY_ID, 0, 0, TYPE_CARD_VIA8233, }, /* VT8233 */
+ /* 0x1106, 0x3058 */
+ { PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_82C686_5, PCI_ANY_ID, PCI_ANY_ID, 0, 0, TYPE_CARD_VIA686, }, /* 686A */
+ /* 0x1106, 0x3059 */
+ { PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_8233_5, PCI_ANY_ID, PCI_ANY_ID, 0, 0, TYPE_CARD_VIA8233, }, /* VT8233 */
{ 0, }
};
@@ -550,7 +559,7 @@ static void snd_via82xx_codec_write(ac97_t *ac97,
{
via82xx_t *chip = ac97->private_data;
unsigned int xval;
-
+
xval = !ac97->num ? VIA_REG_AC97_CODEC_ID_PRIMARY : VIA_REG_AC97_CODEC_ID_SECONDARY;
xval <<= VIA_REG_AC97_CODEC_ID_SHIFT;
xval |= reg << VIA_REG_AC97_CMD_SHIFT;
@@ -598,14 +607,15 @@ static void snd_via82xx_channel_reset(via82xx_t *chip, viadev_t *viadev)
outb(0x00, VIADEV_REG(viadev, OFFSET_TYPE)); /* for via686 */
// outl(0, VIADEV_REG(viadev, OFFSET_CURR_PTR));
viadev->lastpos = 0;
+ viadev->hwptr_done = 0;
}
/*
* Interrupt handler
+ * Used for 686 and 8233A
*/
-
-static irqreturn_t snd_via82xx_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t snd_via686_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
via82xx_t *chip = dev_id;
unsigned int status;
@@ -624,13 +634,23 @@ static irqreturn_t snd_via82xx_interrupt(int irq, void *dev_id, struct pt_regs *
for (i = 0; i < chip->num_devs; i++) {
viadev_t *viadev = &chip->devs[i];
unsigned char c_status = inb(VIADEV_REG(viadev, OFFSET_STATUS));
- c_status &= (VIA_REG_STAT_EOL|VIA_REG_STAT_FLAG|VIA_REG_STAT_STOPPED);
- if (! c_status)
+ if (! (c_status & (VIA_REG_STAT_EOL|VIA_REG_STAT_FLAG|VIA_REG_STAT_STOPPED)))
continue;
if (viadev->substream && viadev->running) {
+ /*
+ * Update hwptr_done based on 'period elapsed'
+ * interrupts. We'll use it, when the chip returns 0
+ * for OFFSET_CURR_COUNT.
+ */
+ if (c_status & VIA_REG_STAT_EOL)
+ viadev->hwptr_done = 0;
+ else
+ viadev->hwptr_done += viadev->fragsize;
+ viadev->in_interrupt = c_status;
spin_unlock(&chip->reg_lock);
snd_pcm_period_elapsed(viadev->substream);
spin_lock(&chip->reg_lock);
+ viadev->in_interrupt = 0;
}
outb(c_status, VIADEV_REG(viadev, OFFSET_STATUS)); /* ack */
}
@@ -639,6 +659,60 @@ static irqreturn_t snd_via82xx_interrupt(int irq, void *dev_id, struct pt_regs *
}
/*
+ * Interrupt handler
+ */
+static irqreturn_t snd_via8233_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+{
+ via82xx_t *chip = dev_id;
+ unsigned int status;
+ unsigned int i;
+ int irqreturn = 0;
+
+ /* check status for each stream */
+ spin_lock(&chip->reg_lock);
+ status = inl(VIAREG(chip, SGD_SHADOW));
+
+ for (i = 0; i < chip->num_devs; i++) {
+ viadev_t *viadev = &chip->devs[i];
+ snd_pcm_substream_t *substream;
+ unsigned char c_status, shadow_status;
+
+ shadow_status = (status >> viadev->shadow_shift) &
+ (VIA8233_SHADOW_STAT_ACTIVE|VIA_REG_STAT_EOL|
+ VIA_REG_STAT_FLAG);
+ c_status = shadow_status & (VIA_REG_STAT_EOL|VIA_REG_STAT_FLAG);
+ if (!c_status)
+ continue;
+
+ substream = viadev->substream;
+ if (substream && viadev->running) {
+ /*
+ * Update hwptr_done based on 'period elapsed'
+ * interrupts. We'll use it, when the chip returns 0
+ * for OFFSET_CURR_COUNT.
+ */
+ if (c_status & VIA_REG_STAT_EOL)
+ viadev->hwptr_done = 0;
+ else
+ viadev->hwptr_done += viadev->fragsize;
+ viadev->in_interrupt = c_status;
+ if (shadow_status & VIA8233_SHADOW_STAT_ACTIVE)
+ viadev->in_interrupt |= VIA_REG_STAT_ACTIVE;
+ spin_unlock(&chip->reg_lock);
+
+ snd_pcm_period_elapsed(substream);
+
+ spin_lock(&chip->reg_lock);
+ viadev->in_interrupt = 0;
+ }
+ outb(c_status, VIADEV_REG(viadev, OFFSET_STATUS)); /* ack */
+ irqreturn = 1;
+ }
+ spin_unlock(&chip->reg_lock);
+ return IRQ_RETVAL(irqreturn);
+}
+
+/*
* PCM callbacks
*/
@@ -701,6 +775,8 @@ static inline unsigned int calc_linear_pos(viadev_t *viadev, unsigned int idx, u
size = viadev->idx_table[idx].size;
base = viadev->idx_table[idx].offset;
res = base + size - count;
+ if (res >= viadev->bufsize)
+ res -= viadev->bufsize;
/* check the validity of the calculated position */
if (size < count) {
@@ -730,9 +806,6 @@ static inline unsigned int calc_linear_pos(viadev_t *viadev, unsigned int idx, u
}
}
}
- viadev->lastpos = res; /* remember the last position */
- if (res >= viadev->bufsize)
- res -= viadev->bufsize;
return res;
}
@@ -760,6 +833,7 @@ static snd_pcm_uframes_t snd_via686_pcm_pointer(snd_pcm_substream_t *substream)
else /* CURR_PTR holds the address + 8 */
idx = ((ptr - (unsigned int)viadev->table.addr) / 8 - 1) % viadev->tbl_entries;
res = calc_linear_pos(viadev, idx, count);
+ viadev->lastpos = res; /* remember the last position */
spin_unlock(&chip->reg_lock);
return bytes_to_frames(substream->runtime, res);
@@ -773,30 +847,44 @@ static snd_pcm_uframes_t snd_via8233_pcm_pointer(snd_pcm_substream_t *substream)
via82xx_t *chip = snd_pcm_substream_chip(substream);
viadev_t *viadev = (viadev_t *)substream->runtime->private_data;
unsigned int idx, count, res;
- int timeout = 5000;
+ int status;
snd_assert(viadev->tbl_entries, return 0);
- if (!(inb(VIADEV_REG(viadev, OFFSET_STATUS)) & VIA_REG_STAT_ACTIVE))
- return 0;
+
spin_lock(&chip->reg_lock);
- do {
- count = inl(VIADEV_REG(viadev, OFFSET_CURR_COUNT));
- /* some mobos read 0 count */
- if ((count & 0xffffff) || ! viadev->running)
- break;
- } while (--timeout);
- if (! timeout)
- snd_printd(KERN_ERR "zero position is read\n");
- idx = count >> 24;
- if (idx >= viadev->tbl_entries) {
+ count = inl(VIADEV_REG(viadev, OFFSET_CURR_COUNT));
+ status = viadev->in_interrupt;
+ if (!status)
+ status = inb(VIADEV_REG(viadev, OFFSET_STATUS));
+
+ if (!(status & VIA_REG_STAT_ACTIVE)) {
+ res = 0;
+ goto unlock;
+ }
+ if (count & 0xffffff) {
+ idx = count >> 24;
+ if (idx >= viadev->tbl_entries) {
#ifdef POINTER_DEBUG
- printk("fail: invalid idx = %i/%i\n", idx, viadev->tbl_entries);
+ printk("fail: invalid idx = %i/%i\n", idx, viadev->tbl_entries);
#endif
- res = viadev->lastpos;
+ res = viadev->lastpos;
+ } else {
+ count &= 0xffffff;
+ res = calc_linear_pos(viadev, idx, count);
+ }
} else {
- count &= 0xffffff;
- res = calc_linear_pos(viadev, idx, count);
- }
+ res = viadev->hwptr_done;
+ if (!viadev->in_interrupt) {
+ if (status & VIA_REG_STAT_EOL) {
+ res = 0;
+ } else
+ if (status & VIA_REG_STAT_FLAG) {
+ res += viadev->fragsize;
+ }
+ }
+ }
+unlock:
+ viadev->lastpos = res;
spin_unlock(&chip->reg_lock);
return bytes_to_frames(substream->runtime, res);
@@ -1241,9 +1329,10 @@ static snd_pcm_ops_t snd_via8233_capture_ops = {
};
-static void init_viadev(via82xx_t *chip, int idx, unsigned int reg_offset, int direction)
+static void init_viadev(via82xx_t *chip, int idx, unsigned int reg_offset, int shadow_pos, int direction)
{
chip->devs[idx].reg_offset = reg_offset;
+ chip->devs[idx].shadow_shift = shadow_pos * 4;
chip->devs[idx].direction = direction;
chip->devs[idx].port = chip->port + reg_offset;
}
@@ -1273,9 +1362,9 @@ static int __devinit snd_via8233_pcm_new(via82xx_t *chip)
chip->pcms[0] = pcm;
/* set up playbacks */
for (i = 0; i < 4; i++)
- init_viadev(chip, i, 0x10 * i, 0);
+ init_viadev(chip, i, 0x10 * i, i, 0);
/* capture */
- init_viadev(chip, chip->capture_devno, VIA_REG_CAPTURE_8233_STATUS, 1);
+ init_viadev(chip, chip->capture_devno, VIA_REG_CAPTURE_8233_STATUS, 6, 1);
if ((err = snd_pcm_lib_preallocate_pages_for_all(pcm, SNDRV_DMA_TYPE_DEV_SG,
snd_dma_pci_data(chip->pci), 64*1024, 128*1024)) < 0)
@@ -1291,9 +1380,9 @@ static int __devinit snd_via8233_pcm_new(via82xx_t *chip)
strcpy(pcm->name, chip->card->shortname);
chip->pcms[1] = pcm;
/* set up playback */
- init_viadev(chip, chip->multi_devno, VIA_REG_MULTPLAY_STATUS, 0);
+ init_viadev(chip, chip->multi_devno, VIA_REG_MULTPLAY_STATUS, 4, 0);
/* set up capture */
- init_viadev(chip, chip->capture_devno + 1, VIA_REG_CAPTURE_8233_STATUS + 0x10, 1);
+ init_viadev(chip, chip->capture_devno + 1, VIA_REG_CAPTURE_8233_STATUS + 0x10, 7, 1);
if ((err = snd_pcm_lib_preallocate_pages_for_all(pcm, SNDRV_DMA_TYPE_DEV_SG,
snd_dma_pci_data(chip->pci), 64*1024, 128*1024)) < 0)
@@ -1326,9 +1415,9 @@ static int __devinit snd_via8233a_pcm_new(via82xx_t *chip)
strcpy(pcm->name, chip->card->shortname);
chip->pcms[0] = pcm;
/* set up playback */
- init_viadev(chip, chip->multi_devno, VIA_REG_MULTPLAY_STATUS, 0);
+ init_viadev(chip, chip->multi_devno, VIA_REG_MULTPLAY_STATUS, 4, 0);
/* capture */
- init_viadev(chip, chip->capture_devno, VIA_REG_CAPTURE_8233_STATUS, 1);
+ init_viadev(chip, chip->capture_devno, VIA_REG_CAPTURE_8233_STATUS, 6, 1);
if ((err = snd_pcm_lib_preallocate_pages_for_all(pcm, SNDRV_DMA_TYPE_DEV_SG,
snd_dma_pci_data(chip->pci), 64*1024, 128*1024)) < 0)
@@ -1347,7 +1436,7 @@ static int __devinit snd_via8233a_pcm_new(via82xx_t *chip)
strcpy(pcm->name, chip->card->shortname);
chip->pcms[1] = pcm;
/* set up playback */
- init_viadev(chip, chip->playback_devno, 0x30, 0);
+ init_viadev(chip, chip->playback_devno, 0x30, 3, 0);
if ((err = snd_pcm_lib_preallocate_pages_for_all(pcm, SNDRV_DMA_TYPE_DEV_SG,
snd_dma_pci_data(chip->pci), 64*1024, 128*1024)) < 0)
@@ -1377,8 +1466,8 @@ static int __devinit snd_via686_pcm_new(via82xx_t *chip)
pcm->private_data = chip;
strcpy(pcm->name, chip->card->shortname);
chip->pcms[0] = pcm;
- init_viadev(chip, 0, VIA_REG_PLAYBACK_STATUS, 0);
- init_viadev(chip, 1, VIA_REG_CAPTURE_STATUS, 1);
+ init_viadev(chip, 0, VIA_REG_PLAYBACK_STATUS, 0, 0);
+ init_viadev(chip, 1, VIA_REG_CAPTURE_STATUS, 0, 1);
if ((err = snd_pcm_lib_preallocate_pages_for_all(pcm, SNDRV_DMA_TYPE_DEV_SG,
snd_dma_pci_data(chip->pci), 64*1024, 128*1024)) < 0)
@@ -2134,7 +2223,10 @@ static int __devinit snd_via82xx_create(snd_card_t * card,
return err;
}
chip->port = pci_resource_start(pci, 0);
- if (request_irq(pci->irq, snd_via82xx_interrupt, SA_INTERRUPT|SA_SHIRQ,
+ if (request_irq(pci->irq,
+ chip_type == TYPE_VIA8233 ?
+ snd_via8233_interrupt : snd_via686_interrupt,
+ SA_INTERRUPT|SA_SHIRQ,
card->driver, (void *)chip)) {
snd_printk("unable to grab IRQ %d\n", pci->irq);
snd_via82xx_free(chip);