linux-kernel - Re: [PATCH v1] ALSA: hda: cs35l41: Stop creating ALSA Controls for firmware coefficients

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Message-ID: <013bdb56-b940-4881-b881-ad12be7321d0@perex.cz>
Date: Tue, 30 Jul 2024 16:55:19 +0200
From: Jaroslav Kysela <perex@...ex.cz>
To: Stefan Binding <sbinding@...nsource.cirrus.com>,
 Takashi Iwai <tiwai@...e.com>
Cc: alsa-devel@...a-project.org, linux-sound@...r.kernel.org,
 linux-kernel@...r.kernel.org, patches@...nsource.cirrus.com
Subject: Re: [PATCH v1] ALSA: hda: cs35l41: Stop creating ALSA Controls for
 firmware coefficients

On 30. 07. 24 16:37, Stefan Binding wrote:
> Add a kernel parameter to allow coefficients to be exposed as ALSA controls.
> 
> When the CS35L41 loads its firmware, it has a number of controls to
> affect its behaviour. Currently, these controls are exposed as ALSA
> Controls by default.
> 
> However, nothing in userspace currently uses them, and is unlikely to
> do so in the future, therefore we don't need to create ASLA controls
> for them.
> 
> These controls can be useful for debug, so we can add a kernel
> parameter to re-enable them if necessary.
> 
> Disabling these controls would prevent userspace from trying to read
> these controls when the CS35L41 is hibernating, which ordinarily
> would result in an error message.

This is probably not a right argument to add this code. The codec should be 
powered up when those controls are accessed or those controls should be cached 
by the driver.

Although the controls have not been used yet, exposing them in this way is not 
ideal.

Could you fix the driver (no I/O errors)?

					Jaroslav

-- 
Jaroslav Kysela <perex@...ex.cz>
Linux Sound Maintainer; ALSA Project; Red Hat, Inc.