linux-kernel - Re: [PATCH v6 12/16] dmaengine: tegra-apb: Clean up suspend-resume

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Message-ID: <e787bee2-4b52-1643-b3a5-8c4e70f6fdca@nvidia.com>
Date:   Thu, 30 Jan 2020 14:09:41 +0000
From:   Jon Hunter <jonathanh@...dia.com>
To:     Dmitry Osipenko <digetx@...il.com>,
        Laxman Dewangan <ldewangan@...dia.com>,
        Vinod Koul <vkoul@...nel.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Michał Mirosław <mirq-linux@...e.qmqm.pl>
CC:     <dmaengine@...r.kernel.org>, <linux-tegra@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v6 12/16] dmaengine: tegra-apb: Clean up suspend-resume


On 30/01/2020 04:38, Dmitry Osipenko wrote:
> It is enough to check whether hardware is busy on suspend and to reset
> it across of suspend-resume because channel's configuration is fully
> re-programmed on each DMA transaction anyways and because save-restore
> of an active channel won't end up well without pausing transfer prior to
> saving of the state (note that all channels shall be idling at the time of
> suspend, so save-restore is not needed at all).

I guess if we ever wanted to support SNDRV_PCM_INFO_PAUSE for audio and
support the pause callback, then saving and restoring the channels could
be needed. Right now I believe that it will just terminate_all transfers
for audio on entering suspend. Any value in keeping this?

Jon

-- 
nvpublic