dmasound audio patch

[Bill Fink <billfink@mindspring.com>]

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Hi,

A friend of mine, Rob Scott, worked up a patch to the dmasound driver
that fixes some of the PPC endianness issues by doing byte swapping
in the driver.  He uses it on a Titanium PowerBook, and I am using it
on a dual 500 MHz G4 with good results.  Before the patch, using xmms
with the AudioCD Reader plugin, I had to use the esound driver since
the OSS driver just gave static.  Now I can use the OSS driver directly,
so there's no need to run the esd daemon.

I know this patch probably isn't politically correct, since as I understand
it Linus doesn't believe that things such as byte swapping should be done
in the kernel.  But then he lives on a little endian machine and doesn't
need to mess with dozens of broken audio applications.  So if you're not
worried about kernel political correctness, you might want to give this
patch a try.  Of course I make no warranty of any kind, but I can attest
that it works fine on a couple of different PPC systems with BenH kernels
around 2.4.18.

						-Bill

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diff -ur .orig/dmasound_awacs.c .mod/dmasound_awacs.c
--- .orig/dmasound_awacs.c	Tue Feb 26 09:35:34 2002
+++ .mod/dmasound_awacs.c	Tue Feb 26 23:17:40 2002
@@ -753,6 +753,16 @@
 			dmasound.dsp.size = size;
 		}
 	}
+	else {
+		dmasound.soft.format = req_format;
+		dmasound.soft.size = size;
+		dmasound.hard.format = format;
+		if (dmasound.minDev == SND_DEV_DSP) {
+			dmasound.dsp.format = format;
+			dmasound.dsp.size = size;
+		}
+		format = req_format;
+	}
 
 	return format;
 }
@@ -2692,7 +2702,7 @@
 __init set_hw_byteswap(struct device_node *io)
 {
 	struct device_node *mio ;
-	unsigned int *p, kl = 0 ;
+	unsigned int kl = 0 ;
 
 	/* if seems that Keylargo can't byte-swap  */
 
diff -ur .orig/dmasound_core.c .mod/dmasound_core.c
--- .orig/dmasound_core.c	Tue Feb 26 09:35:34 2002
+++ .mod/dmasound_core.c	Tue Feb 26 23:17:40 2002
@@ -1263,7 +1263,7 @@
 			if (result < 0)
 				return result;
 			if (format != data)
-				return -EINVAL;
+				return -ENOSYS;
 			return 0;
 		} else
 			return -EINVAL ;
diff -ur .orig/trans_16.c .mod/trans_16.c
--- .orig/trans_16.c	Tue Feb 26 09:35:35 2002
+++ .mod/trans_16.c	Tue Feb 26 23:17:40 2002
@@ -163,23 +163,30 @@
 	ssize_t count, used;
 	int stereo = dmasound.soft.stereo;
 	short *fp = (short *) &frame[*frameUsed];
+	short *up = (short *) userPtr;
 
 	frameLeft >>= 2;
 	userCount >>= (stereo? 2: 1);
 	used = count = min_t(unsigned long, userCount, frameLeft);
-	if (!stereo) {
-		short *up = (short *) userPtr;
-		while (count > 0) {
-			short data;
+	while (count > 0) {
+		short data;
+		if (get_user(data, up++))
+			return -EFAULT;
+		if ((dmasound.hard.format == AFMT_S16_BE) && (dmasound.soft.format == AFMT_S16_LE)) {
+			*fp++ = swab16( data );
+		} else {
+			*fp++ = data;
+		}
+		if (stereo) {
 			if (get_user(data, up++))
 				return -EFAULT;
+		}
+		if ((dmasound.hard.format == AFMT_S16_BE) && (dmasound.soft.format == AFMT_S16_LE)) {
+			*fp++ = swab16( data );
+		} else {
 			*fp++ = data;
-			*fp++ = data;
-			count--;
 		}
-	} else {
-		if (copy_from_user(fp, userPtr, count * 4))
-			return -EFAULT;
+		count--;
 	}
 	*frameUsed += used * 4;
 	return stereo? used * 4: used * 2;
@@ -203,13 +210,21 @@
 		if (get_user(data, up++))
 			return -EFAULT;
 		data ^= mask;
-		*fp++ = data;
+		if ((dmasound.hard.format == AFMT_S16_BE) && (dmasound.soft.format == AFMT_S16_LE)) {
+			*fp++ = swab16(data);
+		} else {
+			*fp++ = data;
+		}
 		if (stereo) {
 			if (get_user(data, up++))
 				return -EFAULT;
 			data ^= mask;
 		}
-		*fp++ = data;
+		if ((dmasound.hard.format == AFMT_S16_BE) && (dmasound.soft.format == AFMT_S16_LE)) {
+			*fp++ = swab16(data);
+		} else {
+			*fp++ = data;
+		}
 		count--;
 	}
 	*frameUsed += used * 4;