Re: [PATCH v4 3/5] ALSA: usb-audio: improve module param quirk_flags

[Takashi Iwai]

On Thu, 18 Sep 2025 11:24:32 +0200,
Cryolitia PukNgae via B4 Relay wrote:
> 
> From: Cryolitia PukNgae <cryoli...@uniontech.com>
> 
> For apply and unapply quirk flags more flexibly though param
> 
> Co-developed-by: Takashi Iwai <ti...@suse.de>
> Signed-off-by: Cryolitia PukNgae <cryoli...@uniontech.com>
> ---
>  sound/usb/card.c     |   9 ++--
>  sound/usb/quirks.c   | 119 
> ++++++++++++++++++++++++++++++++++++++++++++++++++-
>  sound/usb/quirks.h   |   3 +-
>  sound/usb/usbaudio.h |   3 ++
>  4 files changed, 126 insertions(+), 8 deletions(-)
> 
> diff --git a/sound/usb/card.c b/sound/usb/card.c
> index 
> 0265206a8e8cf31133e8463c98fe0497d8ace89e..5837677effa1787ef9d7d02714c3ae43b1a8bc79
>  100644
> --- a/sound/usb/card.c
> +++ b/sound/usb/card.c
> @@ -73,8 +73,8 @@ static bool lowlatency = true;
>  static char *quirk_alias[SNDRV_CARDS];
>  static char *delayed_register[SNDRV_CARDS];
>  static bool implicit_fb[SNDRV_CARDS];
> -static unsigned int quirk_flags[SNDRV_CARDS];
>  
> +char *quirk_flags[SNDRV_CARDS];

My preference is to keep this static, but pass the string value to a
function.  That is, define snd_usb_init_quirk_flags() in main.c:

static void snd_usb_init_quirk_flags(struct snd_usb_audio *chip, int indx)
{
        /* old style option found: the position-based integer value */
        if (quirk_flags[idx] &&
            !kstrtou32(quirk_flags[idx], 0, &chip->quirk_flags)) {
                usb_audio_dbg(chip,
                              "Set quirk flags 0x%x from param based on 
position %d for device %04x:%04x\n",
                              chip->quirk_flags, idx,
                              USB_ID_VENDOR(chip->usb_id),
                              USB_ID_PRODUCT(chip->usb_id));
                return;
        }

        /* take the default quirk from the quirk table */
        snd_usb_init_quirk_flags_table(chip);

        /* add or correct quirk bits from options */
        for (i = 0; i < ARRAY_SIZE(quirk_flags); i++) {
                char *val __free(kfree) = NULL;

                if (!quirk_flags[i] || !*quirk_flags[i])
                        continue;
                
                val = kstrdup(quirk_flags[i], GFP_KERNEL);
                if (!val)
                        return;

                snd_usb_parse_quirk_string(chip, val);
        }
}
        
static int snd_usb_audio_create(....)
{
        ....
        snd_usb_init_quirk_flags(chip, idx);
        ....
}

The function snd_usb_parse_quirk_string() is defined in quirks.c,

void snd_usb_parse_quirk_string(struct snd_usb_audio *chip, char *val)
{
        for (p = val; p && *p;) {
                /* Each entry consists of VID:PID:flags */
                field = strsep(&p, ":");
                if (!field)
                        break;
                .....
        }
}


thanks,

Takashi