linux-kernel - Re: [PATCH v7 14/19] dmaengine: tegra-apb: Keep clock enabled only during of DMA transfer

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Message-ID: <3133d4e3-7623-9342-f26c-5de8b4e6b8c6@gmail.com>
Date:   Thu, 6 Feb 2020 17:31:45 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Jon Hunter <jonathanh@...dia.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 v7 14/19] dmaengine: tegra-apb: Keep clock enabled only
 during of DMA transfer

06.02.2020 16:50, Jon Hunter пишет:
> 
> On 02/02/2020 22:28, Dmitry Osipenko wrote:
>> It's a bit impractical to enable hardware's clock at the time of DMA
>> channel's allocation because most of DMA client drivers allocate DMA
>> channel at the time of the driver's probing, and thus, DMA clock is kept
>> always-enabled in practice, defeating the whole purpose of runtime PM.
>>
>> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
>> ---
>>  drivers/dma/tegra20-apb-dma.c | 35 ++++++++++++++++++++++++-----------
>>  1 file changed, 24 insertions(+), 11 deletions(-)
> What about something like ......
> @@ -581,6 +582,7 @@ static bool handle_continuous_head_request(struct tegra_dma_channel *tdc,
>  	hsgreq = list_first_entry(&tdc->pending_sg_req, typeof(*hsgreq), node);
>  	if (!hsgreq->configured) {
>  		tegra_dma_stop(tdc);
> +		pm_runtime_put(tdc->tdma->dev);
>  		dev_err(tdc2dev(tdc), "Error in DMA transfer, aborting DMA\n");
>  		tegra_dma_abort_all(tdc);
>  		return false;

Yes, that it's what you suggested to do in the reply to v6.

Alright, I'll drop v7 patch #13 and add the put to this patch #14.