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From:   Tzung-Bi Shih <tzungbi@google.com>
Date:   Wed, 13 May 2020 19:58:12 +0800
Message-ID: <CA+Px+wU_tjgWgG_xPR6SNBC5oM3nzVnhxjD85mrxfZW+_w6mKQ@mail.gmail.com>
Subject: Re: [V3 PATCH 2/2] ASoC: max98390: Added Amplifier Driver
To:     Mark Brown <broonie@kernel.org>
Cc:     Steve Lee <steves.lee.maxim@gmail.com>, jack.yu@realtek.com,
        ALSA development <alsa-devel@alsa-project.org>,
        ryan.lee.maxim@gmail.com, ckeepax@opensource.cirrus.com,
        ryans.lee@maximintegrated.com, steves.lee@maximintegrated.com,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Takashi Iwai <tiwai@suse.com>,
        Krzysztof Kozlowski <krzk@kernel.org>,
        Liam Girdwood <lgirdwood@gmail.com>, nuno.sa@analog.com,
        geert@linux-m68k.org, dmurphy@ti.com,
        =?UTF-8?B?U2h1bWluZyBb6IyD5pu46YqYXQ==?= <shumingf@realtek.com>,
        Srini Kandagatla <srinivas.kandagatla@linaro.org>,
        rf@opensource.wolfsonmicro.com
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On Wed, May 13, 2020 at 6:53 PM Mark Brown <broonie@kernel.org> wrote:
>
> On Wed, May 13, 2020 at 04:45:23PM +0900, Steve Lee wrote:
>
> > Changes since V2:
> >       * Removed warn massage in max98390_dsm_calib_get func
> >         and add comment.
>
> The problem isn't the warning, the problem is that you have an empty
> operation.  You should either implement the function (eg, by caching the
> value written) or remove it and fix whatever problems you were running
> into further up the stack when it's missing.

The purpose for the mixer control is: to signal max98390 to start to
calibrate from userspace.
Thus,
max98390_dsm_calib_get() -> do nothing.
max98390_dsm_calib_put() -> call max98390_dsm_calibrate().