linux-kernel - Re: [PATCH] ALSA: usb-audio: fix Hamedal C20 usb camero disconnect issue

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Date:   Fri, 04 Nov 2022 09:06:24 +0100
From:   Takashi Iwai <tiwai@...e.de>
To:     aichao <aichao@...inos.cn>
Cc:     perex@...ex.cz, tiwai@...e.com, alsa-devel@...a-project.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ALSA: usb-audio: fix Hamedal C20 usb camero disconnect issue

On Fri, 04 Nov 2022 08:35:18 +0100,
aichao wrote:
> 
> For Hamedal C20, the current rate is different from the runtime rate,
> snd_usb_endpoint stop and close endpoint to resetting rate.
> if snd_usb_endpoint close the endpoint, sometimes usb will
>  disconnect the device.
> 
> Signed-off-by: aichao <aichao@...inos.cn>

OK, this is more understandable than the previous one.

But it doesn't look like a proper workaround, and we need to figure
out the culprit more deeply.  The interface is anyway reset once when
the parameter is changed / re-setup.  Doesn't it hit the same problem?
Or it's about clearing the interface and keep it for long time?

In anyway, please give lsusb -v output of the device.

BTW, is aichao your full name?  The sign-off must be with the real
full name, and it's a legal requirement.


thanks,

Takashi


> ---
>  sound/usb/endpoint.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/sound/usb/endpoint.c b/sound/usb/endpoint.c
> index 533919a28856..c19e420b1780 100644
> --- a/sound/usb/endpoint.c
> +++ b/sound/usb/endpoint.c
> @@ -825,7 +825,9 @@ void snd_usb_endpoint_close(struct snd_usb_audio *chip,
>  	usb_audio_dbg(chip, "Closing EP 0x%x (count %d)\n",
>  		      ep->ep_num, ep->opened);
>  
> -	if (!--ep->iface_ref->opened)
> +	if (!--ep->iface_ref->opened
> +		&& (le16_to_cpu(chip->dev->descriptor.idVendor) != 0x0525)
> +		&& (le16_to_cpu(chip->dev->descriptor.idProduct) != 0xa4ad))
>  		endpoint_set_interface(chip, ep, false);
>  
>  	if (!--ep->opened) {
> -- 
> 2.25.1
>