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

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Date:   Tue, 7 Dec 2021 17:30:44 +0530
From:   Sameer Pujar <spujar@...dia.com>
To:     Dmitry Osipenko <digetx@...il.com>, tiwai@...e.com,
        broonie@...nel.org, lgirdwood@...il.com, robh+dt@...nel.org,
        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>
Subject: Re: [PATCH 1/3] ALSA: hda/tegra: Skip reset on BPMP devices



On 12/7/2021 3:52 PM, Dmitry Osipenko wrote:
> 07.12.2021 09:32, Sameer Pujar пишет:
>> HDA regression is recently reported on Tegra194 based platforms.
>> This happens because "hda2codec_2x" reset does not really exist
>> in Tegra194 and it causes probe failure. All the HDA based audio
>> tests fail at the moment. This underlying issue is exposed by
>> commit c045ceb5a145 ("reset: tegra-bpmp: Handle errors in BPMP
>> response") which now checks return code of BPMP command response.
>>
>> The failure can be fixed by avoiding above reset in the driver,
>> but the explicit reset is not necessary for Tegra devices which
>> depend on BPMP. On such devices, BPMP ensures reset application
>> during unpowergate calls. Hence skip reset on these devices
>> which is applicable for Tegra186 and later.
> The power domain is shared with the display, AFAICS. The point of reset
> is to bring h/w into predictable state. It doesn't make sense to me to
> skip the reset.

Yes the power-domain is shared with display. As mentioned above, 
explicit reset in driver is not really necessary since BPMP is already 
doing it during unpowergate stage. So the h/w is already ensured to be 
in a good state.