From afbd9b8448f4b7d15673c6858012f384f18d28b8 Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai@suse.de>
Date: Thu, 8 Jul 2010 18:40:37 +0200
Subject: [PATCH] ALSA: hda - Limit the amp value to write

Check the amp max value at put callbacks and set the upper limit
so that the driver won't write any invalid value over the defined
range.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 sound/pci/hda/hda_codec.c | 32 +++++++++++++++++++++-----------
 1 file changed, 21 insertions(+), 11 deletions(-)

diff --git a/sound/pci/hda/hda_codec.c b/sound/pci/hda/hda_codec.c
index a3d638c8c1fd..88a1c6acbcbd 100644
--- a/sound/pci/hda/hda_codec.c
+++ b/sound/pci/hda/hda_codec.c
@@ -1539,6 +1539,17 @@ void snd_hda_codec_resume_amp(struct hda_codec *codec)
 EXPORT_SYMBOL_HDA(snd_hda_codec_resume_amp);
 #endif /* SND_HDA_NEEDS_RESUME */
 
+static u32 get_amp_max_value(struct hda_codec *codec, hda_nid_t nid, int dir,
+			     unsigned int ofs)
+{
+	u32 caps = query_amp_caps(codec, nid, dir);
+	/* get num steps */
+	caps = (caps & AC_AMPCAP_NUM_STEPS) >> AC_AMPCAP_NUM_STEPS_SHIFT;
+	if (ofs < caps)
+		caps -= ofs;
+	return caps;
+}
+
 /**
  * snd_hda_mixer_amp_volume_info - Info callback for a standard AMP mixer
  *
@@ -1553,23 +1564,17 @@ int snd_hda_mixer_amp_volume_info(struct snd_kcontrol *kcontrol,
 	u8 chs = get_amp_channels(kcontrol);
 	int dir = get_amp_direction(kcontrol);
 	unsigned int ofs = get_amp_offset(kcontrol);
-	u32 caps;
 
-	caps = query_amp_caps(codec, nid, dir);
-	/* num steps */
-	caps = (caps & AC_AMPCAP_NUM_STEPS) >> AC_AMPCAP_NUM_STEPS_SHIFT;
-	if (!caps) {
+	uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
+	uinfo->count = chs == 3 ? 2 : 1;
+	uinfo->value.integer.min = 0;
+	uinfo->value.integer.max = get_amp_max_value(codec, nid, dir, ofs);
+	if (!uinfo->value.integer.max) {
 		printk(KERN_WARNING "hda_codec: "
 		       "num_steps = 0 for NID=0x%x (ctl = %s)\n", nid,
 		       kcontrol->id.name);
 		return -EINVAL;
 	}
-	if (ofs < caps)
-		caps -= ofs;
-	uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
-	uinfo->count = chs == 3 ? 2 : 1;
-	uinfo->value.integer.min = 0;
-	uinfo->value.integer.max = caps;
 	return 0;
 }
 EXPORT_SYMBOL_HDA(snd_hda_mixer_amp_volume_info);
@@ -1594,8 +1599,13 @@ update_amp_value(struct hda_codec *codec, hda_nid_t nid,
 		 int ch, int dir, int idx, unsigned int ofs,
 		 unsigned int val)
 {
+	unsigned int maxval;
+
 	if (val > 0)
 		val += ofs;
+	maxval = get_amp_max_value(codec, nid, dir, ofs);
+	if (val > maxval)
+		val = maxval;
 	return snd_hda_codec_amp_update(codec, nid, ch, dir, idx,
 					HDA_AMP_VOLMASK, val);
 }
-- 
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