ALSA : au88x0 - Limit number of channels to fix Oops via OSS emu

Fix playback/capture channels patch to change supported playback
channels of au8830 to 1,2,4 and capture channels to 1,2.
This prevent oops when oss emulation use SNDCTL_DSP_CHANNELS to
set 3 Channels

Signed-off-by: Raymond Yau <superquad.vortex2@gmail.com>
Cc: <stable@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 20 insertions, 4 deletions

diff --git a/sound/pci/au88x0/au88x0_pcm.c b/sound/pci/au88x0/au88x0_pcm.c
index b9d2f202cf9b..5439d662d104 100644
--- a/sound/pci/au88x0/au88x0_pcm.c
+++ b/sound/pci/au88x0/au88x0_pcm.c
@@ -42,11 +42,7 @@ static struct snd_pcm_hardware snd_vortex_playback_hw_adb = {
         .rate_min = 5000,
         .rate_max = 48000,
         .channels_min = 1,
-#ifdef CHIP_AU8830
-        .channels_max = 4,
-#else
         .channels_max = 2,
-#endif
         .buffer_bytes_max = 0x10000,
         .period_bytes_min = 0x1,
         .period_bytes_max = 0x1000,
@@ -115,6 +111,17 @@ static struct snd_pcm_hardware snd_vortex_playback_hw_wt = {
         .periods_max = 64,
 };
 #endif
+#ifdef CHIP_AU8830
+static unsigned int au8830_channels[3] = {
+        1, 2, 4,
+};
+
+static struct snd_pcm_hw_constraint_list hw_constraints_au8830_channels = {
+        .count = ARRAY_SIZE(au8830_channels),
+        .list = au8830_channels,
+        .mask = 0,
+};
+#endif
 /* open callback */
 static int snd_vortex_pcm_open(struct snd_pcm_substream *substream)
 {
@@ -156,6 +163,15 @@ static int snd_vortex_pcm_open(struct snd_pcm_substream *substream)
                 if (VORTEX_PCM_TYPE(substream->pcm) == VORTEX_PCM_ADB
                     || VORTEX_PCM_TYPE(substream->pcm) == VORTEX_PCM_I2S)
                         runtime->hw = snd_vortex_playback_hw_adb;
+#ifdef CHIP_AU8830
+                if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK &&
+                        VORTEX_PCM_TYPE(substream->pcm) == VORTEX_PCM_ADB) {
+                        runtime->hw.channels_max = 4;
+                        snd_pcm_hw_constraint_list(runtime, 0,
+                                SNDRV_PCM_HW_PARAM_CHANNELS,
+                                &hw_constraints_au8830_channels);
+                }
+#endif
                 substream->runtime->private_data = NULL;
         }
 #ifndef CHIP_AU8810