linux-kernel - RE: [PATCH v18 2/4] dmaengine: tegra: Add tegra gpcdma driver

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Date:   Fri, 4 Feb 2022 06:47:42 +0000
From:   Akhil R <akhilrajeev@...dia.com>
To:     Dmitry Osipenko <digetx@...il.com>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "dmaengine@...r.kernel.org" <dmaengine@...r.kernel.org>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Krishna Yarlagadda <kyarlagadda@...dia.com>,
        Laxman Dewangan <ldewangan@...dia.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
        "p.zabel@...gutronix.de" <p.zabel@...gutronix.de>,
        Rajesh Gumasta <rgumasta@...dia.com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "thierry.reding@...il.com" <thierry.reding@...il.com>,
        "vkoul@...nel.org" <vkoul@...nel.org>
CC:     Pavan Kunapuli <pkunapuli@...dia.com>
Subject: RE: [PATCH v18 2/4] dmaengine: tegra: Add tegra gpcdma driver

> 03.02.2022 06:44, Akhil R пишет:
> >> But why do you need to pause at all here and can't use
> >> tegra_dma_stop_client() even if pause is supported?
> > The recommended method to terminate a transfer in
> > between is to pause the channel first and then disable it.
> > This is more graceful and stable for the hardware.
> > stop_client() is more abrupt, though it does the job.
> 
> If there is no real practical difference, then I'd use the common method
> only. This will make code cleaner and simpler a tad.
This is the documented way of clean exit from a transfer, especially for
cyclic transfers where the DMA is configured in continuous mode.
I guess it might not be a good idea to deviate from that unless there is
something demanding it compulsorily.

I agree that the code will be cleaner. I would try to see if I can find a cleaner
way to do this. Please do let me know if you have any suggestion.

Thanks,
Akhil