ASoC: au1x: PSC-AC97 bugfixes

This patch fixes the following bugs:

- only reprogram bitdepth if it has changed since last call to hw_params.
- add locking inside ac97_read/write functions:
  When reprogramming sample depth, the ac97 unit has to be disabled,
  which should not be done in the middle of codec register accesses.

- retry timed-out codec register accesses.

- wait for status bits to set/clear when starting/stopping various
  functional blocks; very important after reenabling AC97 unit else
  sound may be distorted (e.g. high-pitch noise in 1kHz sine wave).

- clear fifos before/after starting/stopping RX/TX.

- longer timeouts waiting for PSC/AC97 ready after cold reset
  with certain codecs this can take ridiculous amounts of time.

Run-tested on various Au1200 platforms with various codecs.

Signed-off-by: Manuel Lauss <manuel.lauss@gmail.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

1 files changed, 96 insertions, 33 deletions

diff --git a/sound/soc/au1x/psc-ac97.c b/sound/soc/au1x/psc-ac97.c
index 479d7bdf1865..a521aa90ddee 100644
--- a/sound/soc/au1x/psc-ac97.c
+++ b/sound/soc/au1x/psc-ac97.c
@@ -1,8 +1,8 @@
 /*
  * Au12x0/Au1550 PSC ALSA ASoC audio support.
  *
- * (c) 2007-2008 MSC Vertriebsges.m.b.H.,
- *      Manuel Lauss <mano@roarinelk.homelinux.net>
+ * (c) 2007-2009 MSC Vertriebsges.m.b.H.,
+ *      Manuel Lauss <manuel.lauss@gmail.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
@@ -19,6 +19,7 @@
 #include <linux/module.h>
 #include <linux/device.h>
 #include <linux/delay.h>
+#include <linux/mutex.h>
 #include <linux/suspend.h>
 #include <sound/core.h>
 #include <sound/pcm.h>
@@ -29,6 +30,9 @@
 
 #include "psc.h"
 
+/* how often to retry failed codec register reads/writes */
+#define AC97_RW_RETRIES 5
+
 #define AC97_DIR        \
         (SND_SOC_DAIDIR_PLAYBACK | SND_SOC_DAIDIR_CAPTURE)
 
@@ -45,6 +49,9 @@
 #define AC97PCR_CLRFIFO(stype)  \
         ((stype) == PCM_TX ? PSC_AC97PCR_TC : PSC_AC97PCR_RC)
 
+#define AC97STAT_BUSY(stype)    \
+        ((stype) == PCM_TX ? PSC_AC97STAT_TB : PSC_AC97STAT_RB)
+
 /* instance data. There can be only one, MacLeod!!!! */
 static struct au1xpsc_audio_data *au1xpsc_ac97_workdata;
 
@@ -54,24 +61,33 @@ static unsigned short au1xpsc_ac97_read(struct snd_ac97 *ac97,
 {
         /* FIXME */
         struct au1xpsc_audio_data *pscdata = au1xpsc_ac97_workdata;
-        unsigned short data, tmo;
+        unsigned short data, retry, tmo;
 
-        au_writel(PSC_AC97CDC_RD | PSC_AC97CDC_INDX(reg), AC97_CDC(pscdata));
+        au_writel(PSC_AC97EVNT_CD, AC97_EVNT(pscdata));
         au_sync();
 
-        tmo = 1000;
-        while ((!(au_readl(AC97_EVNT(pscdata)) & PSC_AC97EVNT_CD)) && --tmo)
-                udelay(2);
+        retry = AC97_RW_RETRIES;
+        do {
+                mutex_lock(&pscdata->lock);
+
+                au_writel(PSC_AC97CDC_RD | PSC_AC97CDC_INDX(reg),
+                          AC97_CDC(pscdata));
+                au_sync();
+
+                tmo = 2000;
+                while ((!(au_readl(AC97_EVNT(pscdata)) & PSC_AC97EVNT_CD))
+                        && --tmo)
+                        udelay(2);
 
-        if (!tmo)
-                data = 0xffff;
-        else
                 data = au_readl(AC97_CDC(pscdata)) & 0xffff;
 
-        au_writel(PSC_AC97EVNT_CD, AC97_EVNT(pscdata));
-        au_sync();
+                au_writel(PSC_AC97EVNT_CD, AC97_EVNT(pscdata));
+                au_sync();
+
+                mutex_unlock(&pscdata->lock);
+        } while (--retry && !tmo);
 
-        return data;
+        return retry ? data : 0xffff;
 }
 
 /* AC97 controller writes to codec register */
@@ -80,16 +96,29 @@ static void au1xpsc_ac97_write(struct snd_ac97 *ac97, unsigned short reg,
 {
         /* FIXME */
         struct au1xpsc_audio_data *pscdata = au1xpsc_ac97_workdata;
-        unsigned int tmo;
+        unsigned int tmo, retry;
 
-        au_writel(PSC_AC97CDC_INDX(reg) | (val & 0xffff), AC97_CDC(pscdata));
+        au_writel(PSC_AC97EVNT_CD, AC97_EVNT(pscdata));
         au_sync();
-        tmo = 1000;
-        while ((!(au_readl(AC97_EVNT(pscdata)) & PSC_AC97EVNT_CD)) && --tmo)
+
+        retry = AC97_RW_RETRIES;
+        do {
+                mutex_lock(&pscdata->lock);
+
+                au_writel(PSC_AC97CDC_INDX(reg) | (val & 0xffff),
+                          AC97_CDC(pscdata));
                 au_sync();
 
-        au_writel(PSC_AC97EVNT_CD, AC97_EVNT(pscdata));
-        au_sync();
+                tmo = 2000;
+                while ((!(au_readl(AC97_EVNT(pscdata)) & PSC_AC97EVNT_CD))
+                       && --tmo)
+                        udelay(2);
+
+                au_writel(PSC_AC97EVNT_CD, AC97_EVNT(pscdata));
+                au_sync();
+
+                mutex_unlock(&pscdata->lock);
+        } while (--retry && !tmo);
 }
 
 /* AC97 controller asserts a warm reset */
@@ -129,9 +158,9 @@ static void au1xpsc_ac97_cold_reset(struct snd_ac97 *ac97)
         au_sync();
 
         /* wait for PSC to indicate it's ready */
-        i = 100000;
+        i = 1000;
         while (!((au_readl(AC97_STAT(pscdata)) & PSC_AC97STAT_SR)) && (--i))
-                au_sync();
+                msleep(1);
 
         if (i == 0) {
                 printk(KERN_ERR "au1xpsc-ac97: PSC not ready!\n");
@@ -143,9 +172,9 @@ static void au1xpsc_ac97_cold_reset(struct snd_ac97 *ac97)
         au_sync();
 
         /* wait for AC97 core to become ready */
-        i = 100000;
+        i = 1000;
         while (!((au_readl(AC97_STAT(pscdata)) & PSC_AC97STAT_DR)) && (--i))
-                au_sync();
+                msleep(1);
         if (i == 0)
                 printk(KERN_ERR "au1xpsc-ac97: AC97 ctrl not ready\n");
 }
@@ -165,12 +194,12 @@ static int au1xpsc_ac97_hw_params(struct snd_pcm_substream *substream,
 {
         /* FIXME */
         struct au1xpsc_audio_data *pscdata = au1xpsc_ac97_workdata;
-        unsigned long r, stat;
+        unsigned long r, ro, stat;
         int chans, stype = SUBSTREAM_TYPE(substream);
 
         chans = params_channels(params);
 
-        r = au_readl(AC97_CFG(pscdata));
+        r = ro = au_readl(AC97_CFG(pscdata));
         stat = au_readl(AC97_STAT(pscdata));
 
         /* already active? */
@@ -180,9 +209,6 @@ static int au1xpsc_ac97_hw_params(struct snd_pcm_substream *substream,
                     (pscdata->rate != params_rate(params)))
                         return -EINVAL;
         } else {
-                /* disable AC97 device controller first */
-                au_writel(r & ~PSC_AC97CFG_DE_ENABLE, AC97_CFG(pscdata));
-                au_sync();
 
                 /* set sample bitdepth: REG[24:21]=(BITS-2)/2 */
                 r &= ~PSC_AC97CFG_LEN_MASK;
@@ -199,14 +225,40 @@ static int au1xpsc_ac97_hw_params(struct snd_pcm_substream *substream,
                         r |= PSC_AC97CFG_RXSLOT_ENA(4);
                 }
 
-                /* finally enable the AC97 controller again */
+                /* do we need to poke the hardware? */
+                if (!(r ^ ro))
+                        goto out;
+
+                /* ac97 engine is about to be disabled */
+                mutex_lock(&pscdata->lock);
+
+                /* disable AC97 device controller first... */
+                au_writel(r & ~PSC_AC97CFG_DE_ENABLE, AC97_CFG(pscdata));
+                au_sync();
+
+                /* ...wait for it... */
+                while (au_readl(AC97_STAT(pscdata)) & PSC_AC97STAT_DR)
+                        asm volatile ("nop");
+
+                /* ...write config... */
+                au_writel(r, AC97_CFG(pscdata));
+                au_sync();
+
+                /* ...enable the AC97 controller again... */
                 au_writel(r | PSC_AC97CFG_DE_ENABLE, AC97_CFG(pscdata));
                 au_sync();
 
+                /* ...and wait for ready bit */
+                while (!(au_readl(AC97_STAT(pscdata)) & PSC_AC97STAT_DR))
+                        asm volatile ("nop");
+
+                mutex_unlock(&pscdata->lock);
+
                 pscdata->cfg = r;
                 pscdata->rate = params_rate(params);
         }
 
+out:
         return 0;
 }
 
@@ -222,6 +274,8 @@ static int au1xpsc_ac97_trigger(struct snd_pcm_substream *substream,
         switch (cmd) {
         case SNDRV_PCM_TRIGGER_START:
         case SNDRV_PCM_TRIGGER_RESUME:
+                au_writel(AC97PCR_CLRFIFO(stype), AC97_PCR(pscdata));
+                au_sync();
                 au_writel(AC97PCR_START(stype), AC97_PCR(pscdata));
                 au_sync();
                 break;
@@ -229,6 +283,13 @@ static int au1xpsc_ac97_trigger(struct snd_pcm_substream *substream,
         case SNDRV_PCM_TRIGGER_SUSPEND:
                 au_writel(AC97PCR_STOP(stype), AC97_PCR(pscdata));
                 au_sync();
+
+                while (au_readl(AC97_STAT(pscdata)) & AC97STAT_BUSY(stype))
+                        asm volatile ("nop");
+
+                au_writel(AC97PCR_CLRFIFO(stype), AC97_PCR(pscdata));
+                au_sync();
+
                 break;
         default:
                 ret = -EINVAL;
@@ -251,6 +312,8 @@ static int au1xpsc_ac97_probe(struct platform_device *pdev,
         if (!au1xpsc_ac97_workdata)
                 return -ENOMEM;
 
+        mutex_init(&au1xpsc_ac97_workdata->lock);
+
         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
         if (!r) {
                 ret = -ENODEV;
@@ -269,9 +332,9 @@ static int au1xpsc_ac97_probe(struct platform_device *pdev,
                 goto out1;
 
         /* configuration: max dma trigger threshold, enable ac97 */
-         au1xpsc_ac97_workdata->cfg = PSC_AC97CFG_RT_FIFO8 |
-                                      PSC_AC97CFG_TT_FIFO8 |
-                                      PSC_AC97CFG_DE_ENABLE;
+        au1xpsc_ac97_workdata->cfg = PSC_AC97CFG_RT_FIFO8 |
+                                     PSC_AC97CFG_TT_FIFO8 |
+                                     PSC_AC97CFG_DE_ENABLE;
 
         /* preserve PSC clock source set up by platform (dev.platform_data
          * is already occupied by soc layer)
@@ -386,4 +449,4 @@ module_exit(au1xpsc_ac97_exit);
 
 MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION("Au12x0/Au1550 PSC AC97 ALSA ASoC audio driver");
-MODULE_AUTHOR("Manuel Lauss <mano@roarinelk.homelinux.net>");
+MODULE_AUTHOR("Manuel Lauss <manuel.lauss@gmail.com>");