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ALSA: usb-audio: Refine string-descriptor-based quirk matching

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Remove snd_usb_get_string() and use the manufacturer and product strings
stored in struct usb_device directly to match quirk table entries. Their
NULLity can be checked to determine if the device has no these strings.
This simplifies the code a lot.

Meanwhile, allow quirk table entries to match "no string" explicitly, and
add appropriate comments to show the expected usages of
DEVICE_STRING_FLG() and VENDOR_STRING_FLG(). These changes are tiny and
doesn't form another separate patch, so that back-and-forth changes can
be avoided.

Suggested-by: Terry Junge <linuxsound@cosmicgizmosystems.com>
Link: https://lore.kernel.org/r/b59da54a-9c80-4212-a337-c5ea98da52d1@cosmicgizmosystems.com
Signed-off-by: Rong Zhang <i@rong.moe>
Link: https://patch.msgid.link/20260305174711.1106324-1-i@rong.moe
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Rong Zhang 2026-03-06 01:46:39 +08:00 committed by Takashi Iwai
parent b364a0d23c
commit 9558a2cbec
1 changed files with 40 additions and 50 deletions
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90
sound/usb/quirks.c
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@ -2153,7 +2153,28 @@ struct usb_audio_quirk_flags_table {
{ .id = USB_ID(vid, pid), .flags = (_flags) }
#define VENDOR_FLG(vid, _flags) DEVICE_FLG(vid, 0, _flags)
/* Use as a last resort if using DEVICE_FLG() is prone to VID/PID conflicts. */
/*
* Use as a last resort if using DEVICE_FLG() is prone to VID/PID conflicts.
*
* Usage:
* // match vid, pid, "manufacturer", and "product"
* DEVICE_STRING_FLG(vid, pid, "manufacturer", "product", flags)
*
* // match vid, pid, "manufacturer", and any product string
* DEVICE_STRING_FLG(vid, pid, "manufacturer", NULL, flags)
*
* // match vid, pid, "manufacturer", and device must have no product string
* DEVICE_STRING_FLG(vid, pid, "manufacturer", "", flags)
*
* // match vid, pid, any manufacturer string, and "product"
* DEVICE_STRING_FLG(vid, pid, NULL, "product", flags)
*
* // match vid, pid, no manufacturer string, and "product"
* DEVICE_STRING_FLG(vid, pid, "", "product", flags)
*
* // match vid, pid, no manufacturer string, and no product string
* DEVICE_STRING_FLG(vid, pid, "", "", flags)
*/
#define DEVICE_STRING_FLG(vid, pid, _manufacturer, _product, _flags) \
{ \
.id = USB_ID(vid, pid), \
@ -2164,7 +2185,16 @@ struct usb_audio_quirk_flags_table {
.flags = (_flags), \
}
/* Use as a last resort if using VENDOR_FLG() is prone to VID conflicts. */
/*
* Use as a last resort if using VENDOR_FLG() is prone to VID conflicts.
*
* Usage:
* // match vid, and "manufacturer"
* VENDOR_STRING_FLG(vid, "manufacturer", flags)
*
* // match vid, and device must have no manufacturer string
* VENDOR_STRING_FLG(vid, "", flags)
*/
#define VENDOR_STRING_FLG(vid, _manufacturer, _flags) \
DEVICE_STRING_FLG(vid, 0, _manufacturer, NULL, _flags)
@ -2595,63 +2625,23 @@ void snd_usb_apply_flag_dbg(const char *reason,
}
}
#define USB_STRING_SIZE 128
static char *snd_usb_get_string(struct snd_usb_audio *chip, int id)
{
char *buf;
int ret;
/*
* Devices without the corresponding string descriptor.
* This is non-fatal as *_STRING_FLG have nothing to do in this case.
*/
if (id == 0)
return ERR_PTR(-ENODATA);
buf = kmalloc(USB_STRING_SIZE, GFP_KERNEL);
if (buf == NULL)
return ERR_PTR(-ENOMEM);
ret = usb_string(chip->dev, id, buf, USB_STRING_SIZE);
if (ret < 0) {
usb_audio_warn(chip, "failed to get string for id%d: %d\n", id, ret);
kfree(buf);
return ERR_PTR(ret);
}
return buf;
}
void snd_usb_init_quirk_flags_table(struct snd_usb_audio *chip)
{
const struct usb_audio_quirk_flags_table *p;
char *manufacturer __free(kfree) = NULL;
char *product __free(kfree) = NULL;
for (p = quirk_flags_table; p->id; p++) {
if (chip->usb_id == p->id ||
(!USB_ID_PRODUCT(p->id) &&
USB_ID_VENDOR(chip->usb_id) == USB_ID_VENDOR(p->id))) {
/* Handle DEVICE_STRING_FLG/VENDOR_STRING_FLG. */
if (p->usb_string_match && p->usb_string_match->manufacturer) {
if (!manufacturer) {
manufacturer = snd_usb_get_string(chip,
chip->dev->descriptor.iManufacturer);
}
if (IS_ERR_OR_NULL(manufacturer) ||
strcmp(p->usb_string_match->manufacturer, manufacturer))
continue;
}
if (p->usb_string_match && p->usb_string_match->product) {
if (!product) {
product = snd_usb_get_string(chip,
chip->dev->descriptor.iProduct);
}
if (IS_ERR_OR_NULL(product) ||
strcmp(p->usb_string_match->product, product))
continue;
}
if (p->usb_string_match && p->usb_string_match->manufacturer &&
strcmp(p->usb_string_match->manufacturer,
chip->dev->manufacturer ? chip->dev->manufacturer : ""))
continue;
if (p->usb_string_match && p->usb_string_match->product &&
strcmp(p->usb_string_match->product,
chip->dev->product ? chip->dev->product : ""))
continue;
snd_usb_apply_flag_dbg("builtin table", chip, p->flags);
chip->quirk_flags |= p->flags;