linux-kernel - Re: [PATCH 1/3] ALSA: hda/tegra: Skip reset on BPMP devices

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Date:   Tue, 7 Dec 2021 18:35:21 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Sameer Pujar <spujar@...dia.com>, tiwai@...e.com,
        broonie@...nel.org, lgirdwood@...il.com, thierry.reding@...il.com,
        perex@...ex.cz
Cc:     jonathanh@...dia.com, alsa-devel@...a-project.org,
        devicetree@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Mohan Kumar <mkumard@...dia.com>, robh+dt@...nel.org
Subject: Re: [PATCH 1/3] ALSA: hda/tegra: Skip reset on BPMP devices

07.12.2021 17:49, Sameer Pujar пишет:
...
>>> How the reload case would be different? Can you please specify more
>>> details if you are referring to a particular scenario?
>> You have a shared power domain. Since power domain can be turned off
>> only when nobody keeps domain turned on, you now making reset of HDA
>> controller dependent on the state of display driver.
> 
> I don't think that the state of display driver would affect. The HDA
> driver itself can issue unpowergate calls which in turn ensures h/w
> reset. If display driver is already runtime active, HDA driver runtime
> resume after this would be still fine since h/w reset is already applied
> during display runtime resume. Note that both HDA and display resets are
> connected to this power-domain and BPMP applies these resets during
> unpowergate.

HDA won't be reset while display is active on T186+.
HDA will be reset while is display is inactive on T186+.
HDA will be reset regardless of display state on pre-T186.

This is a pure inconsistency of the reset behaviour. Please don't do it.