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

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Message-ID: <56bb43b6-8d72-b1de-4402-a2cb31707bd9@gmail.com>
Date:   Tue, 7 Dec 2021 15:05:42 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Sameer Pujar <spujar@...dia.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

07.12.2021 15:00, Sameer Pujar пишет:
> 
> 
> 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.

If you'll reload the driver module, then h/w won't be reset.