From e8bdb6bbab60a8731f21823c86391f176d052348 Mon Sep 17 00:00:00 2001 From: Daniel Mack Date: Fri, 11 Jun 2010 17:34:22 +0200 Subject: ALSA: usb-audio: fix UAC2 control value queries For RANGE requests, we should only query as much bytes as we're in fact interested in. For CUR requests, we shouldn't confuse the firmware with an overlong request but just ask for 2 bytes. This might need fixing in the future as it's not entirely clear when to dispatch 1-byte, 2-byte and 4-byte request blocks. For now, we assume everything is coded in 16bit - this works for all firmware implementations I've seen. Signed-off-by: Daniel Mack Reported-by: Alex Lee Signed-off-by: Takashi Iwai --- sound/usb/mixer.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-) (limited to 'sound/usb') diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c index a060d005e20..6939d0f517d 100644 --- a/sound/usb/mixer.c +++ b/sound/usb/mixer.c @@ -297,20 +297,27 @@ static int get_ctl_value_v1(struct usb_mixer_elem_info *cval, int request, int v static int get_ctl_value_v2(struct usb_mixer_elem_info *cval, int request, int validx, int *value_ret) { - unsigned char buf[14]; /* enough space for one range of 4 bytes */ + unsigned char buf[2 + 3*sizeof(__u16)]; /* enough space for one range */ unsigned char *val; - int ret; + int ret, size; __u8 bRequest; - bRequest = (request == UAC_GET_CUR) ? - UAC2_CS_CUR : UAC2_CS_RANGE; + if (request == UAC_GET_CUR) { + bRequest = UAC2_CS_CUR; + size = sizeof(__u16); + } else { + bRequest = UAC2_CS_RANGE; + size = sizeof(buf); + } + + memset(buf, 0, sizeof(buf)); ret = snd_usb_ctl_msg(cval->mixer->chip->dev, usb_rcvctrlpipe(cval->mixer->chip->dev, 0), bRequest, USB_RECIP_INTERFACE | USB_TYPE_CLASS | USB_DIR_IN, validx, cval->mixer->ctrlif | (cval->id << 8), - buf, sizeof(buf), 1000); + buf, size, 1000); if (ret < 0) { snd_printk(KERN_ERR "cannot get ctl value: req = %#x, wValue = %#x, wIndex = %#x, type = %d\n", @@ -318,6 +325,8 @@ static int get_ctl_value_v2(struct usb_mixer_elem_info *cval, int request, int v return ret; } + /* FIXME: how should we handle multiple triplets here? */ + switch (request) { case UAC_GET_CUR: val = buf; -- cgit v1.2.3-70-g09d2