Alsa-Devel Archive on lore.kernel.org
 help / color / mirror / Atom feed
From: Eldad Zack <eldad@fogrefinery.com>
To: Takashi Iwai <tiwai@suse.de>, Jaroslav Kysela <perex@perex.cz>,
	Daniel Mack <zonque@gmail.com>
Cc: alsa-devel@alsa-project.org, Eldad Zack <eldad@fogrefinery.com>
Subject: [PATCH, for-next] ALSA: usb-audio: caiaq: fix endianness bug in snd_usb_caiaq_maschine_dispatch
Date: Mon, 29 Apr 2013 21:15:46 +0200	[thread overview]
Message-ID: <1367262946-8980-1-git-send-email-eldad@fogrefinery.com> (raw)

Current code does this:

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

Which is effectively (neglecting the index):

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

This means the int16 in the buffer is not converted at all.

Daniel Mack confirmed that the driver works on little endian
CPUs, leading to the conclusion that the device-side structure
is actually little endian.
This changes the code to use le16_to_cpu().

Caught by sparse.

Acked-by: Daniel Mack <zonque@gmail.com>
Signed-off-by: Eldad Zack <eldad@fogrefinery.com>
---
 sound/usb/caiaq/input.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/sound/usb/caiaq/input.c b/sound/usb/caiaq/input.c
index efc70ae..4b3fb91 100644
--- a/sound/usb/caiaq/input.c
+++ b/sound/usb/caiaq/input.c
@@ -488,13 +488,13 @@ 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

             reply	other threads:[~2013-04-29 19:15 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-04-29 19:15 Eldad Zack [this message]
2013-04-29 19:20 ` [PATCH, for-next] ALSA: usb-audio: caiaq: fix endianness bug in snd_usb_caiaq_maschine_dispatch Daniel Mack
2013-04-30  7:19   ` Takashi Iwai

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1367262946-8980-1-git-send-email-eldad@fogrefinery.com \
    --to=eldad@fogrefinery.com \
    --cc=alsa-devel@alsa-project.org \
    --cc=perex@perex.cz \
    --cc=tiwai@suse.de \
    --cc=zonque@gmail.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox