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ALSA: usb-audio: Fix the missing ctl name suffix at parsing SU 

The commit 89b89d121f ("ALSA: usb-audio: Add check return value for
usb_string()") added the check of the return value from
snd_usb_copy_string_desc(), which is correct per se, but it introduced
a regression.  In the original code, either the "Clock Source",
"Playback Source" or "Capture Source" suffix is added after the
terminal string, while the commit changed it to add the suffix only
when get_term_name() is failing.  It ended up with an incorrect ctl
name like "PCM" instead of "PCM Capture Source".

Also, even the original code has a similar bug: when the ctl name is
generated from snd_usb_copy_string_desc() for the given iSelector, it
also doesn't put the suffix.

This patch addresses these issues: the suffix is added always when no
static mapping is found.  Also the patch tries to put more comments
and cleans up the if/else block for better readability in order to
avoid the same pitfall again.

Fixes: 89b89d121f ("ALSA: usb-audio: Add check return value for usb_string()")
Reported-and-tested-by: Mauro Santos <registo.mailling@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Iwai 2017-12-18 23:36:57 +01:00
parent 9226665159
commit 5a15f289ee
1 changed files with 16 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

27
sound/usb/mixer.c
View File

@ -2173,20 +2173,25 @@ static int parse_audio_selector_unit(struct mixer_build *state, int unitid,
kctl->private_value = (unsigned long)namelist;
kctl->private_free = usb_mixer_selector_elem_free;
nameid = uac_selector_unit_iSelector(desc);
/* check the static mapping table at first */
len = check_mapped_name(map, kctl->id.name, sizeof(kctl->id.name));
if (len)
;
else if (nameid)
len = snd_usb_copy_string_desc(state, nameid, kctl->id.name,
sizeof(kctl->id.name));
else
len = get_term_name(state, &state->oterm,
kctl->id.name, sizeof(kctl->id.name), 0);
if (!len) {
strlcpy(kctl->id.name, "USB", sizeof(kctl->id.name));
/* no mapping ? */
/* if iSelector is given, use it */
nameid = uac_selector_unit_iSelector(desc);
if (nameid)
len = snd_usb_copy_string_desc(state, nameid,
kctl->id.name,
sizeof(kctl->id.name));
/* ... or pick up the terminal name at next */
if (!len)
len = get_term_name(state, &state->oterm,
kctl->id.name, sizeof(kctl->id.name), 0);
/* ... or use the fixed string "USB" as the last resort */
if (!len)
strlcpy(kctl->id.name, "USB", sizeof(kctl->id.name));
/* and add the proper suffix */
if (desc->bDescriptorSubtype == UAC2_CLOCK_SELECTOR)
append_ctl_name(kctl, " Clock Source");
else if ((state->oterm.type & 0xff00) == 0x0100)