linux-kernel - [PATCH 3.16.y-ckt 022/128] ALSA: rme96: Fix unexpected volume reset after rate changes

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Message-Id: <1453672883-2708-23-git-send-email-luis.henriques@canonical.com>
Date:	Sun, 24 Jan 2016 21:59:37 +0000
From:	Luis Henriques <luis.henriques@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Takashi Iwai <tiwai@...e.de>,
	Luis Henriques <luis.henriques@...onical.com>
Subject: [PATCH 3.16.y-ckt 022/128] ALSA: rme96: Fix unexpected volume reset after rate changes

3.16.7-ckt23 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

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: Luis Henriques <luis.henriques@...onical.com>
---
 sound/pci/rme96.c | 41 ++++++++++++++++++++++++++---------------
 1 file changed, 26 insertions(+), 15 deletions(-)

diff --git a/sound/pci/rme96.c b/sound/pci/rme96.c
index 76169929770d..bde4c7330f30 100644
--- a/sound/pci/rme96.c
+++ b/sound/pci/rme96.c
@@ -742,10 +742,11 @@ 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
@@ -983,6 +984,7 @@ 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);
@@ -996,24 +998,26 @@ 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? */
 	}
+
+	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 =
@@ -1024,9 +1028,16 @@ snd_rme96_playback_hw_params(struct snd_pcm_substream *substream,
 		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