[alsa-devel] ALSA: usb-audio: caiaq: endianness bug

[Eldad Zack]

Hi Daniel,

I think I found a endian usage issue in the caiaq driver. I have a patch 
to fix it (below), but it assumes that the driver works currently on 
little endian CPUs - I don't have a device to test it with.

Cheers,
Eldad

-- >8 --
Subject: [PATCH] ALSA: usb-audio: caiaq: fix endianness bug

Current code does this:

  be16_to_cpu(buf[i * 2] << 8 | buf[(i * 2) + 1])

Which is effectively:

  be16_to_cpu(be16_to_cpu(*((u16 *) buf)))

This means the int16 in the buffer is not converted at all.
Assuming the device-side structure is actually little endian,
change the code to use le16_to_cpu().

Signed-off-by: Eldad Zack <eldad at fogrefinery.com>
---
 sound/usb/caiaq/input.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/sound/usb/caiaq/input.c b/sound/usb/caiaq/input.c
index efc70ae..2f4ae4d 100644
--- a/sound/usb/caiaq/input.c
+++ b/sound/usb/caiaq/input.c
@@ -488,13 +488,12 @@ static void snd_usb_caiaq_maschine_dispatch(struct snd_usb_caiaqdev *cdev,
 					unsigned int len)
 {
 	unsigned int i, pad_id;
-	uint16_t pressure;
+	__le16 *pressure = (__le16 *) buf;
 
 	for (i = 0; i < MASCHINE_PADS; i++) {
-		pressure = be16_to_cpu(buf[i * 2] << 8 | buf[(i * 2) + 1]);
-		pad_id = pressure >> 12;
-
-		input_report_abs(cdev->input_dev, MASCHINE_PAD(pad_id), pressure & 0xfff);
+		pad_id = le16_to_cpu(*pressure) >> 12;
+		input_report_abs(cdev->input_dev, MASCHINE_PAD(pad_id), le16_to_cpu(*pressure) & 0xfff);
+		pressure++;
 	}
 
 	input_sync(cdev->input_dev);
-- 
1.8.1.5