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From:   Yu-Hsuan Hsu <yuhsuan@chromium.org>
Date:   Tue, 30 Jun 2020 20:25:28 +0800
Message-ID: <CAGvk5PqqMKikj46yfvNYdiQ=3cWoHVLBgQKGOPs5iuoFWUBs=Q@mail.gmail.com>
Subject: Re: [PATCH] ASoC: rockchip: add format and rate constraints on rk3399
To:     Mark Brown <broonie@kernel.org>
Cc:     linux-kernel@vger.kernel.org, Liam Girdwood <lgirdwood@gmail.com>,
        Jaroslav Kysela <perex@perex.cz>,
        Takashi Iwai <tiwai@suse.com>,
        Heiko Stuebner <heiko@sntech.de>, alsa-devel@alsa-project.org,
        linux-arm-kernel@lists.infradead.org,
        linux-rockchip@lists.infradead.org,
        Cheng-Yi Chiang <cychiang@chromium.org>,
        Tzung-Bi Shih <tzungbi@chromium.org>
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Mark Brown <broonie@kernel.org> =E6=96=BC 2020=E5=B9=B46=E6=9C=8830=E6=97=
=A5 =E9=80=B1=E4=BA=8C =E4=B8=8B=E5=8D=886:40=E5=AF=AB=E9=81=93=EF=BC=9A
>
> On Tue, Jun 30, 2020 at 05:16:15PM +0800, Yu-Hsuan Hsu wrote:
> > S8 and S24 formats does not work on this machine driver so force to use
> > S16_LE instead.
>
> > In addition, add constraint to limit the max value of rate because the
> > rate higher than 96000(172000, 192000) is not stable either.
>
> What is the source of these restrictions - are they due to the component
> devices?  If they are then the component devices ought to be setting
> suitable constraints themselves.

I'm not sure why it happened. But I guess it is not the issues on those
components because they work normally on other machine drivers.
Because this driver is old and lacks maintenance, I think we can just
filter some unstable formats. Actually, those formats are very rarely
used as well.