linux-kernel - [PATCH 4.1 023/127] ALSA: rme96: Fix unexpected volume reset after rate changes

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Message-Id: <20160127180806.853450767@linuxfoundation.org>
Date:	Wed, 27 Jan 2016 10:13:07 -0800
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Takashi Iwai <tiwai@...e.de>
Subject: [PATCH 4.1 023/127] ALSA: rme96: Fix unexpected volume reset after rate changes

4.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Takashi Iwai <tiwai@...e.de>

commit a74a821624c0c75388a193337babd17a8c02c740 upstream.

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@...e.fr>
Signed-off-by: Takashi Iwai <tiwai@...e.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 sound/pci/rme96.c |   41 ++++++++++++++++++++++++++---------------
 1 file changed, 26 insertions(+), 15 deletions(-)

--- a/sound/pci/rme96.c
+++ b/sound/pci/rme96.c
@@ -741,10 +741,11 @@ snd_rme96_playback_setrate(struct 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_
 	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 +995,26 @@ snd_rme96_playback_hw_params(struct snd_
 	{
                 /* 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? */
 	}
+
+	err = snd_rme96_playback_setformat(rme96, params_format(params));
+	if (err < 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 =
@@ -1021,9 +1025,16 @@ snd_rme96_playback_hw_params(struct snd_
 		rme96->wcreg &= ~(RME96_WCR_PRO | RME96_WCR_DOLBY | RME96_WCR_EMP);
 		writel(rme96->wcreg |= rme96->wcreg_spdif_stream, rme96->iobase + RME96_IO_CONTROL_REGISTER);
 	}
+
+	err = 0;
+ error:
 	spin_unlock_irq(&rme96->lock);
-		
-	return 0;
+	if (apply_dac_volume) {
+		usleep_range(3000, 10000);
+		snd_rme96_apply_dac_volume(rme96);
+	}
+
+	return err;
 }
 
 static int