[alsa-devel] [bug] Volume at maximum when track with different frequency is played with my RME sound card

[Takashi Iwai]

On Fri, 04 Dec 2015 16:14:56 +0100,
Maeda wrote:
> 
> OK :)
> 
> Tested-by: Sylvain LABOISNE <maeda1 at free.fr>

Thanks, the official fix is below.  It'll be included in 4.4-rc5
(slipped from rc4) and backported to stable kernels later.


Takashi

-- 8< --
From: Takashi Iwai <tiwai at suse.de>
Subject: [PATCH] ALSA: rme96: Fix unexpected volume reset after rate changes

rme96 driver needs to reset DAC depending on the sample rate, and this
results in resetting to the max volume suddenly.  It's because of the
missing call of snd_rme96_apply_dac_volume().

However, calling this function right after the DAC reset still may not
work, and we need some delay before this call.  Since the DAC reset
and the procedure after that are performed in the spinlock, we delay
the DAC volume restore at the end after the spinlock.

Reported-and-tested-by: Sylvain LABOISNE <maeda1 at free.fr>
Cc: <stable at vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai at suse.de>
---
 sound/pci/rme96.c | 37 +++++++++++++++++++++++--------------
 1 file changed, 23 insertions(+), 14 deletions(-)

diff --git a/sound/pci/rme96.c b/sound/pci/rme96.c
index 714df906249e..e4229d01cf6a 100644
--- a/sound/pci/rme96.c
+++ b/sound/pci/rme96.c
@@ -741,10 +741,11 @@ snd_rme96_playback_setrate(struct rme96 *rme96,
 	{
 		/* change to/from double-speed: reset the DAC (if available) */
 		snd_rme96_reset_dac(rme96);
+		return 1; /* need to restore volume */
 	} else {
 		writel(rme96->wcreg, rme96->iobase + RME96_IO_CONTROL_REGISTER);
+		return 0;
 	}
-	return 0;
 }
 
 static int
@@ -980,6 +981,7 @@ snd_rme96_playback_hw_params(struct snd_pcm_substream *substream,
 	struct rme96 *rme96 = snd_pcm_substream_chip(substream);
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	int err, rate, dummy;
+	bool apply_dac_volume = false;
 
 	runtime->dma_area = (void __force *)(rme96->iobase +
 					     RME96_IO_PLAY_BUFFER);
@@ -993,24 +995,24 @@ snd_rme96_playback_hw_params(struct snd_pcm_substream *substream,
 	{
                 /* slave clock */
                 if ((int)params_rate(params) != rate) {
-			spin_unlock_irq(&rme96->lock);
-			return -EIO;                    
-                }
-	} else if ((err = snd_rme96_playback_setrate(rme96, params_rate(params))) < 0) {
-		spin_unlock_irq(&rme96->lock);
-		return err;
-	}
-	if ((err = snd_rme96_playback_setformat(rme96, params_format(params))) < 0) {
-		spin_unlock_irq(&rme96->lock);
-		return err;
+			err = -EIO;
+			goto error;
+		}
+	} else {
+		err = snd_rme96_playback_setrate(rme96, params_rate(params));
+		if (err < 0)
+			goto error;
+		apply_dac_volume = err > 0; /* need to restore volume later? */
 	}
+	if ((err = snd_rme96_playback_setformat(rme96, params_format(params))) < 0)
+		goto error;
 	snd_rme96_setframelog(rme96, params_channels(params), 1);
 	if (rme96->capture_periodsize != 0) {
 		if (params_period_size(params) << rme96->playback_frlog !=
 		    rme96->capture_periodsize)
 		{
-			spin_unlock_irq(&rme96->lock);
-			return -EBUSY;
+			err = -EBUSY;
+			goto error;
 		}
 	}
 	rme96->playback_periodsize =
@@ -1022,8 +1024,15 @@ snd_rme96_playback_hw_params(struct snd_pcm_substream *substream,
 		writel(rme96->wcreg |= rme96->wcreg_spdif_stream, rme96->iobase + RME96_IO_CONTROL_REGISTER);
 	}
 	spin_unlock_irq(&rme96->lock);
+	err = 0;
 		
-	return 0;
+ error:
+	if (apply_dac_volume) {
+		usleep_range(3000, 10000);
+		snd_rme96_apply_dac_volume(rme96);
+	}
+
+	return err;
 }
 
 static int
-- 
2.6.3