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Date:   Tue, 8 Feb 2022 22:52:37 +0300
From:   Alexander Sergeyev <sergeev917@gmail.com>
To:     Takashi Iwai <tiwai@suse.de>
Cc:     Jeremy Szu <jeremy.szu@canonical.com>, tiwai@suse.com,
        "moderated list:SOUND" <alsa-devel@alsa-project.org>,
        Kailang Yang <kailang@realtek.com>,
        open list <linux-kernel@vger.kernel.org>,
        Huacai Chen <chenhuacai@kernel.org>,
        Jian-Hong Pan <jhp@endlessos.org>,
        Hui Wang <hui.wang@canonical.com>,
        PeiSen Hou <pshou@realtek.com>
Subject: Re: [PATCH 1/4] ALSA: hda/realtek: fix mute/micmute LEDs for HP 855
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On Tue, Feb 08, 2022 at 03:36:08PM +0100, Takashi Iwai wrote:
> ... and here is a fix patch for allowing more rebinds.
> Give it a try.

It works, no problems with large numbers of rebinds.

> -- 8< --
> From: Takashi Iwai <tiwai@suse.de>
> Subject: [PATCH] ALSA: hda: Fix driver index handling at re-binding
> 
> HD-audio driver handles the multiple instances and keeps the static
> index that is incremented at each probe.  This becomes a problem when
> user tries to re-bind the device via sysfs multiple times; as the
> device index isn't cleared unlike rmmod case, it points to the next
> element at re-binding, and eventually later you can't probe any more
> when it reaches to SNDRV_CARDS_MAX (usually 32).
> 
> This patch is an attempt to improve the handling at rebinding.
> Instead of a static device index, now we keep a bitmap and assigns to
> the first zero bit position.  At the driver remove, in return, the
> bitmap slot is cleared again, so that it'll be available for the next
> probe.
> 
> Reported-by: Alexander Sergeyev <sergeev917@gmail.com>
> Signed-off-by: Takashi Iwai <tiwai@suse.de>
> ---
>  sound/pci/hda/hda_intel.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
> index 4b0338c4c543..a2922233e85f 100644
> --- a/sound/pci/hda/hda_intel.c
> +++ b/sound/pci/hda/hda_intel.c
> @@ -2064,14 +2064,16 @@ static const struct hda_controller_ops pci_hda_ops = {
>  	.position_check = azx_position_check,
>  };
>  
> +static DECLARE_BITMAP(probed_devs, SNDRV_CARDS);
> +
>  static int azx_probe(struct pci_dev *pci,
>  		     const struct pci_device_id *pci_id)
>  {
> -	static int dev;
>  	struct snd_card *card;
>  	struct hda_intel *hda;
>  	struct azx *chip;
>  	bool schedule_probe;
> +	int dev;
>  	int err;
>  
>  	if (pci_match_id(driver_denylist, pci)) {
> @@ -2079,10 +2081,11 @@ static int azx_probe(struct pci_dev *pci,
>  		return -ENODEV;
>  	}
>  
> +	dev = find_first_zero_bit(probed_devs, SNDRV_CARDS);
>  	if (dev >= SNDRV_CARDS)
>  		return -ENODEV;
>  	if (!enable[dev]) {
> -		dev++;
> +		set_bit(dev, probed_devs);
>  		return -ENOENT;
>  	}
>  
> @@ -2149,7 +2152,7 @@ static int azx_probe(struct pci_dev *pci,
>  	if (schedule_probe)
>  		schedule_delayed_work(&hda->probe_work, 0);
>  
> -	dev++;
> +	set_bit(dev, probed_devs);
>  	if (chip->disabled)
>  		complete_all(&hda->probe_wait);
>  	return 0;
> @@ -2372,6 +2375,7 @@ static void azx_remove(struct pci_dev *pci)
>  		cancel_delayed_work_sync(&hda->probe_work);
>  		device_lock(&pci->dev);
>  
> +		clear_bit(chip->dev_index, probed_devs);
>  		pci_set_drvdata(pci, NULL);
>  		snd_card_free(card);
>  	}
> -- 
> 2.34.1
>