From eab2b553c3d3ed20698c4a9c7e049a60b804e2f5 Mon Sep 17 00:00:00 2001
From: Clemens Ladisch <clemens@ladisch.de>
Date: Mon, 2 Mar 2009 11:45:50 +0100
Subject: [PATCH] sound: usb-audio: fix rules check for 32-channel devices

When storing the channel numbers used by a format, and if the device
happens to support 32 channels, the code would try to store 1<<32 in
a 32-bit value.

Since no valid format can have zero channels, we can use 1<<(channels-1)
instead of 1<<channels so that all the channel numbers that we test for
fit into 32 bits.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 sound/usb/usbaudio.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sound/usb/usbaudio.c b/sound/usb/usbaudio.c
index 2b24496ddec..f853b627cf4 100644
--- a/sound/usb/usbaudio.c
+++ b/sound/usb/usbaudio.c
@@ -1783,7 +1783,7 @@ static int check_hw_params_convention(struct snd_usb_substream *subs)
 			if (rates[f->format] && rates[f->format] != f->rates)
 				goto __out;
 		}
-		channels[f->format] |= (1 << f->channels);
+		channels[f->format] |= 1 << (f->channels - 1);
 		rates[f->format] |= f->rates;
 		/* needs knot? */
 		if (f->rates & SNDRV_PCM_RATE_KNOT)
@@ -1810,7 +1810,7 @@ static int check_hw_params_convention(struct snd_usb_substream *subs)
 			continue;
 		for (i = 0; i < 32; i++) {
 			if (f->rates & (1 << i))
-				channels[i] |= (1 << f->channels);
+				channels[i] |= 1 << (f->channels - 1);
 		}
 	}
 	cmaster = 0;