Re: [PATCH] ALSA: hda/core: Stop capability walk on empty capability header

[Takashi Iwai]

On Mon, 02 Nov 2026 12:49:39 +0100,
Michał Kopeć wrote:
> 
> From: Michal Kopec <michal.kopec@xxxxxxxxx>
> 
> snd_hdac_bus_parse_capabilities() walks the controller's linked
> capability list starting at LLCH. On some platforms one of the entries
> reads back as all zeros. Such a header does not describe a capability,
> but the walk still treats it as one: it falls into the default case and
> reports an error, printing the raw register value instead of the
> capability ID:
> 
>   snd_hda_intel 0000:00:1f.3: Unknown capability 0
> 
> The walk then stops anyway, because the next pointer of a zero header
> is 0, so the message is only noise.
> 
> Treat an all-zero header as the end of the list, the same way a failed
> read (-1) is already handled, and log it at debug level only. Also
> print the capability ID in hex for a genuinely unknown capability,
> instead of the full header value.
> 
> Fixes: 0b00a5615dc4 ("ALSA: hdac_ext: add hdac extended controller")
> Signed-off-by: Michał Kopeć <michal.kopec@xxxxxxxxx>

Applied now.  Thanks.


Takashi