From: "Péter Ujfalusi" <peter.ujfalusi@linux.intel.com>
To: Jaroslav Kysela <perex@perex.cz>, alsa-devel@alsa-project.org
Cc: Takashi Iwai <tiwai@suse.com>, wim.taymans@gmail.com
Subject: Re: UCM vs SOF vs HDMI passthrough
Date: Fri, 12 Apr 2024 14:44:56 +0300 [thread overview]
Message-ID: <96f4709c-6545-454c-b84b-25a78939abf6@linux.intel.com> (raw)
In-Reply-To: <4fe03ef7-881e-4078-a819-cbe6500ede7d@perex.cz>
On 11/04/2024 16:38, Jaroslav Kysela wrote:
> On 11. 04. 24 15:15, Péter Ujfalusi wrote:
>
>> [B] Using UCM
>> https://github.com/ujfalusi/alsa-ucm-conf/tree/topic/sof-hdmi
>
> This is only way to go. The configuration for "legacy" PCM device names
> should be handled through UCM (when UCM config exists for this hw).
OK, I will drop the other option.
>> Should we add some parameter to 'amixer -c0 info', like ipc_version:4/3,
>> so if the ipc_version is 3 or missing we assume that passthrough is not
>> supported?
>
> UCM must be able to detect sound card capabilities. For passthrough,
> there should be some controls for AES bits which may be used for the
> conditional matching. If it's not sufficient, a hint to the components
> string (mixer info structure) may be added by the driver. Also PCM name
> or subname may be matched for a substring, if you like (seems more
> related than the components string).
Thanks for the advice!
I have now something really working in a way it should be.
The kernel will add "hdmi-pt:1" to the card's components when HDMI
passthrough is possible (IPC4, ChainDMA enabled for HDMI PCM). [1]
UCM will use the existence of "hdmi-pt:1" to decide to create the needed
mapping PCMs [2]
[1] https://github.com/thesofproject/linux/pull/4921
[2] https://github.com/ujfalusi/alsa-ucm-conf/tree/topic/sof-hdmi
I'm not sure about the "hdmi-pt:1", can we just have plain "hdmi-pt" or
we need a param:value pair always?
There are still funky things done in the UCM patch due to lack of
experience with it. I guess I should create a formal PR to get it
reviewed and correct, right?
Thank you,
Péter
prev parent reply other threads:[~2024-04-12 18:52 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-11 13:15 UCM vs SOF vs HDMI passthrough Péter Ujfalusi
2024-04-11 13:38 ` Jaroslav Kysela
2024-04-12 11:44 ` Péter Ujfalusi [this message]
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