ALSA: intel8x0: implement ac97_clock whitelist

The AC97 clock detection is not accurate in some cases. This patch adds
an initial whitelist for audio devices gathered from RedHat's bugzilla:

https://bugzilla.redhat.com/show_bug.cgi?id=441087

As a side effect, white-listing might speedup kernel booting (AC97 clock
measuring code is not activated).

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

diff --git a/sound/pci/intel8x0.c b/sound/pci/intel8x0.c
index 73ad589..c8f5148 100644 (file)
--- a/sound/pci/intel8x0.c
+++ b/sound/pci/intel8x0.c
@@ -83,7 +83,7 @@ MODULE_PARM_DESC(index, "Index value for Intel i8x0 soundcard.");
 module_param(id, charp, 0444);
 MODULE_PARM_DESC(id, "ID string for Intel i8x0 soundcard.");
 module_param(ac97_clock, int, 0444);
-MODULE_PARM_DESC(ac97_clock, "AC'97 codec clock (0 = auto-detect).");
+MODULE_PARM_DESC(ac97_clock, "AC'97 codec clock (0 = whitelist + auto-detect, 1 = force autodetect).");
 module_param(ac97_quirk, charp, 0444);
 MODULE_PARM_DESC(ac97_quirk, "AC'97 workaround for strange hardware.");
 module_param(buggy_semaphore, bool, 0444);
@@ -2692,6 +2692,38 @@ static void __devinit intel8x0_measure_ac97_clock(struct intel8x0 *chip)
        snd_ac97_update_power(chip->ac97[0], AC97_PCM_FRONT_DAC_RATE, 0);
 }
 
+struct intel8x0_clock_list {
+       unsigned short subvendor;
+       unsigned short subdevice;
+       unsigned int rate;
+};
+
+static struct intel8x0_clock_list intel8x0_clock_list[] __devinitdata = {
+       { 0x0e11, 0x008a, 41000 },      /* Analog Devices AD1885 */
+       { 0x1028, 0x00be, 44100 },      /* Analog Devices AD1885 */
+       { 0x1028, 0x0177, 48000 },      /* Analog Devices AD1980 */
+       { 0x1043, 0x80f3, 48000 },      /* Analog Devices AD1985 */
+       { 0x0000, 0x0000, 00000 }       /* terminator */
+};
+
+static int __devinit intel8x0_in_clock_list(struct intel8x0 *chip)
+{
+       struct pci_dev *pci = chip->pci;
+       struct intel8x0_clock_list *wl;
+
+       for (wl = intel8x0_clock_list; wl->subvendor; wl++) {
+               if (wl->subvendor == pci->subsystem_vendor &&
+                   wl->subdevice == pci->subsystem_device) {
+                       printk(KERN_INFO "intel8x0: white list rate for %04x:%04x is %i\n",
+                               pci->subsystem_vendor,
+                               pci->subsystem_device, wl->rate);
+                       chip->ac97_bus->clock = wl->rate;
+                       return 1;
+               }
+       }
+       return 0;
+}
+
 #ifdef CONFIG_PROC_FS
 static void snd_intel8x0_proc_read(struct snd_info_entry * entry,
                                   struct snd_info_buffer *buffer)
@@ -3087,8 +3119,14 @@ static int __devinit snd_intel8x0_probe(struct pci_dev *pci,
                 "%s with %s at irq %i", card->shortname,
                 snd_ac97_get_short_name(chip->ac97[0]), chip->irq);
 
-       if (! ac97_clock)
-               intel8x0_measure_ac97_clock(chip);
+       if (ac97_clock == 0 || ac97_clock == 1) {
+               if (ac97_clock == 0) {
+                       if (intel8x0_in_clock_list(chip) == 0)
+                               intel8x0_measure_ac97_clock(chip);
+               } else {
+                       intel8x0_measure_ac97_clock(chip);
+               }
+       }
 
        if ((err = snd_card_register(card)) < 0) {
                snd_card_free(card);