sound: ymfpci: increase timer resolution to 96 kHz

Allow the interval timer to be programmed with its full 96 kHz
precision.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

2 files changed, 16 insertions, 5 deletions

diff --git a/include/sound/ymfpci.h b/include/sound/ymfpci.h
index 05ead6698434..444cd6ba0ba7 100644
--- a/include/sound/ymfpci.h
+++ b/include/sound/ymfpci.h
@@ -331,6 +331,7 @@ struct snd_ymfpci {
         struct snd_ac97 *ac97;
         struct snd_rawmidi *rawmidi;
         struct snd_timer *timer;
+        unsigned int timer_ticks;
 
         struct pci_dev *pci;
         struct snd_card *card;
diff --git a/sound/pci/ymfpci/ymfpci_main.c b/sound/pci/ymfpci/ymfpci_main.c
index 2f0925236a1b..5518371db13f 100644
--- a/sound/pci/ymfpci/ymfpci_main.c
+++ b/sound/pci/ymfpci/ymfpci_main.c
@@ -834,7 +834,7 @@ static irqreturn_t snd_ymfpci_interrupt(int irq, void *dev_id)
         status = snd_ymfpci_readw(chip, YDSXGR_INTFLAG);
         if (status & 1) {
                 if (chip->timer)
-                        snd_timer_interrupt(chip->timer, chip->timer->sticks);
+                        snd_timer_interrupt(chip->timer, chip->timer_ticks);
         }
         snd_ymfpci_writew(chip, YDSXGR_INTFLAG, status);
 
@@ -1885,8 +1885,18 @@ static int snd_ymfpci_timer_start(struct snd_timer *timer)
         unsigned int count;
 
         chip = snd_timer_chip(timer);
-        count = (timer->sticks << 1) - 1;
         spin_lock_irqsave(&chip->reg_lock, flags);
+        if (timer->sticks > 1) {
+                chip->timer_ticks = timer->sticks;
+                count = timer->sticks - 1;
+        } else {
+                /*
+                 * Divisor 1 is not allowed; fake it by using divisor 2 and
+                 * counting two ticks for each interrupt.
+                 */
+                chip->timer_ticks = 2;
+                count = 2 - 1;
+        }
         snd_ymfpci_writew(chip, YDSXGR_TIMERCOUNT, count);
         snd_ymfpci_writeb(chip, YDSXGR_TIMERCTRL, 0x03);
         spin_unlock_irqrestore(&chip->reg_lock, flags);
@@ -1909,14 +1919,14 @@ static int snd_ymfpci_timer_precise_resolution(struct snd_timer *timer,
                                                unsigned long *num, unsigned long *den)
 {
         *num = 1;
-        *den = 48000;
+        *den = 96000;
         return 0;
 }
 
 static struct snd_timer_hardware snd_ymfpci_timer_hw = {
         .flags = SNDRV_TIMER_HW_AUTO,
-        .resolution = 20833, /* 1/fs = 20.8333...us */
-        .ticks = 0x8000,
+        .resolution = 10417, /* 1 / 96 kHz = 10.41666...us */
+        .ticks = 0x10000,
         .start = snd_ymfpci_timer_start,
         .stop = snd_ymfpci_timer_stop,
         .precise_resolution = snd_ymfpci_timer_precise_resolution,