[ALSA] intel8x0: add one retry to the ac97_clock measurement routine

It seems that on some hardware platforms, the first measurement is wrong.
This patch adds second measurement to this case.

Signed-off-by: Jaroslav Kysela <perex@perex.cz>

1 files changed, 11 insertions, 4 deletions

diff --git a/sound/pci/intel8x0.c b/sound/pci/intel8x0.c
index 10f8609e9c6e..5dced5b79387 100644
--- a/sound/pci/intel8x0.c
+++ b/sound/pci/intel8x0.c
@@ -2676,12 +2676,13 @@ static void __devinit intel8x0_measure_ac97_clock(struct intel8x0 *chip)
         struct ichdev *ichdev;
         unsigned long port;
         unsigned long pos, pos1, t;
-        int civ, timeout = 1000;
+        int civ, timeout = 1000, attempt = 1;
         struct timespec start_time, stop_time;
 
         if (chip->ac97_bus->clock != 48000)
                 return; /* specified in module option */
 
+      __again:
         subs = chip->pcm[0]->streams[0].substream;
         if (! subs || subs->dma_buffer.bytes < INTEL8X0_TESTBUF_SIZE) {
                 snd_printk(KERN_WARNING "no playback buffer allocated - aborting measure ac97 clock\n");
@@ -2749,6 +2750,11 @@ static void __devinit intel8x0_measure_ac97_clock(struct intel8x0 *chip)
 
         if (pos == 0) {
                 snd_printk(KERN_ERR "intel8x0: measure - unreliable DMA position..\n");
+              __retry:
+                if (attempt < 2) {
+                        attempt++;
+                        goto __again;
+                }
                 return;
         }
 
@@ -2759,14 +2765,15 @@ static void __devinit intel8x0_measure_ac97_clock(struct intel8x0 *chip)
         printk(KERN_INFO "%s: measured %lu usecs (%lu samples)\n", __func__, t, pos);
         if (t == 0) {
                 snd_printk(KERN_ERR "intel8x0: ?? calculation error..\n");
-                return;
+                goto __retry;
         }
         pos *= 1000;
         pos = (pos / t) * 1000 + ((pos % t) * 1000) / t;
-        if (pos < 40000 || pos >= 60000) 
+        if (pos < 40000 || pos >= 60000) {
                 /* abnormal value. hw problem? */
                 printk(KERN_INFO "intel8x0: measured clock %ld rejected\n", pos);
-        else if (pos > 40500 && pos < 41500)
+                goto __retry;
+        } else if (pos > 40500 && pos < 41500)
                 /* first exception - 41000Hz reference clock */
                 chip->ac97_bus->clock = 41000;
         else if (pos > 43600 && pos < 44600)