linux-kernel - Re: [PATCH v17 2/4] dmaengine: tegra: Add tegra gpcdma driver

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Message-ID: <07aa10e7-22da-3844-8d6a-476ad0ea2e2e@gmail.com>
Date:   Sun, 30 Jan 2022 13:13:53 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Akhil R <akhilrajeev@...dia.com>, devicetree@...r.kernel.org,
        dmaengine@...r.kernel.org, jonathanh@...dia.com,
        kyarlagadda@...dia.com, ldewangan@...dia.com,
        linux-kernel@...r.kernel.org, linux-tegra@...r.kernel.org,
        p.zabel@...gutronix.de, rgumasta@...dia.com, robh+dt@...nel.org,
        thierry.reding@...il.com, vkoul@...nel.org
Cc:     Pavan Kunapuli <pkunapuli@...dia.com>
Subject: Re: [PATCH v17 2/4] dmaengine: tegra: Add tegra gpcdma driver

30.01.2022 13:08, Dmitry Osipenko пишет:
> 30.01.2022 13:05, Dmitry Osipenko пишет:
>> static int tegra_dma_device_resume(struct dma_chan *dc)
>> {
>> 	struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
>> 	u32 val;
>>
>> 	if (!tdc->tdma->chip_data->hw_support_pause)
>> 		return -ENOSYS;
>>
>> 	if (!tdc->dma_desc)
>> 		return 0;
>>
>> 	val = tdc_read(tdc, TEGRA_GPCDMA_CHAN_CSRE);
>> 	val &= ~TEGRA_GPCDMA_CHAN_CSRE_PAUSE;
>> 	tdc_write(tdc, TEGRA_GPCDMA_CHAN_CSRE, val);
>> 	
>> 	enable_irq(tdc->irq);
> 
> Correction:
> 
> if (tdc->dma_desc) {
> 	val = tdc_read(tdc, TEGRA_GPCDMA_CHAN_CSRE);
> 	val &= ~TEGRA_GPCDMA_CHAN_CSRE_PAUSE;
> 	tdc_write(tdc, TEGRA_GPCDMA_CHAN_CSRE, val);
> }
> 
> enable_irq(tdc->irq);

And apparently, tegra_dma_terminate_all() also needs to take care of
removing the PAUSE bit. Otherwise it won't be possible to unpause
channel after the termination.