linux-kernel - Re: [RFC PATCH 7/7] DMA: tegra-adma: Add support for Tegra210 ADMA

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Message-ID: <55DADBE7.80006@nvidia.com>
Date:	Mon, 24 Aug 2015 09:55:03 +0100
From:	Jon Hunter <jonathanh@...dia.com>
To:	Vinod Koul <vinod.koul@...el.com>
CC:	Laxman Dewangan <ldewangan@...dia.com>,
	Stephen Warren <swarren@...dotorg.org>,
	Thierry Reding <thierry.reding@...il.com>,
	"Alexandre Courbot" <gnurou@...il.com>,
	<dmaengine@...r.kernel.org>, <linux-tegra@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>
Subject: Re: [RFC PATCH 7/7] DMA: tegra-adma: Add support for Tegra210 ADMA


On 23/08/15 15:33, Vinod Koul wrote:
> On Tue, Aug 18, 2015 at 02:49:15PM +0100, Jon Hunter wrote:
>> +#define AHUB_TO_MEMORY						2
>> +#define MEMORY_TO_AHUB						4
> 
> namespace this aptly as well
> 
>> +static void tegra_adma_stop(struct tegra_dma_channel *tdc)
>> +{
>> +	u32 status;
>> +
>> +	/* TODO: Do we need to disable interrupts here? */
> 
> when?

Once everyone is happy with the RFC in general.

>> +static void tegra_adma_start(struct tegra_dma_channel *tdc,
>> +		struct tegra_dma_sg_req *sg_req)
>> +{
>> +	struct tegra_adma_chan_regs *ch_regs = &sg_req->adma_ch_regs;
>> +
>> +	/* Update transfer done count for position calculation */
>> +	tdc->adma_ch_regs.tc = ch_regs->tc;
>> +	tdc_write(tdc, ADMA_CH_TC, ch_regs->tc);
>> +	tdc_write(tdc, ADMA_CH_CTRL, ch_regs->ctrl);
>> +	tdc_write(tdc, ADMA_CH_LOWER_SOURCE_ADDR, ch_regs->src_ptr);
>> +	tdc_write(tdc, ADMA_CH_LOWER_TARGET_ADDR, ch_regs->tgt_ptr);
>> +	tdc_write(tdc, ADMA_CH_AHUB_FIFO_CTRL, ch_regs->ahub_fifo_ctrl);
>> +	tdc_write(tdc, ADMA_CH_CONFIG, ch_regs->config);
> empty line here please

Ok.

>> +static int tegra_adma_get_xfer_params(struct tegra_dma_channel *tdc,
>> +				      struct tegra_adma_chan_regs *ch_regs,
>> +				      enum dma_transfer_direction direction)
>> +{
>> +	u32 burst_size, ctrl, ctrl_mask, slave_id, fifo_mask, fifo_shift;
>> +
>> +	ch_regs->ahub_fifo_ctrl = tdc_read(tdc, ADMA_CH_AHUB_FIFO_CTRL);
>> +	ch_regs->config = tdc_read(tdc, ADMA_CH_CONFIG);
>> +	ch_regs->ctrl = tdc_read(tdc, ADMA_CH_CTRL);
>> +	slave_id = tdc->dma_sconfig.slave_id;
>> +
>> +	switch (direction) {
>> +	case DMA_MEM_TO_DEV:
>> +		burst_size = fls(tdc->dma_sconfig.dst_maxburst);
>> +		ctrl_mask = ADMA_CH_CTRL_TX_REQUEST_SELECT_MASK;
>> +		ctrl = MEMORY_TO_AHUB << ADMA_CH_CTRL_TRANSFER_DIRECTION_SHIFT;
>> +		ctrl |= slave_id << ADMA_CH_CTRL_TX_REQUEST_SELECT_SHIFT;
>> +		fifo_mask = ADMA_CH_AHUB_FIFO_CTRL_TX_FIFO_SIZE_MASK;
>> +		fifo_shift = ADMA_CH_AHUB_FIFO_CTRL_TX_FIFO_SIZE_SHIFT;
>> +		break;
> Empty line here pls

Ok, any reason why? Other dma drivers don't appear to do this.

>> +	case DMA_DEV_TO_MEM:
>> +		burst_size = fls(tdc->dma_sconfig.src_maxburst);
>> +		ctrl_mask = ADMA_CH_CTRL_RX_REQUEST_SELECT_MASK;
>> +		ctrl = AHUB_TO_MEMORY << ADMA_CH_CTRL_TRANSFER_DIRECTION_SHIFT;
>> +		ctrl |= slave_id << ADMA_CH_CTRL_RX_REQUEST_SELECT_SHIFT;
>> +		fifo_mask = ADMA_CH_AHUB_FIFO_CTRL_RX_FIFO_SIZE_MASK;
>> +		fifo_shift = ADMA_CH_AHUB_FIFO_CTRL_RX_FIFO_SIZE_SHIFT;
>> +		break;
> 
> here too...
> 
>> +	default:
>> +		dev_err(tdc2dev(tdc), "Dma direction is not supported\n");
>> +		return -EINVAL;
>> +	}
>> +
>> +	if (!burst_size || burst_size > ADMA_BURSTSIZE_16)
>> +		burst_size = ADMA_BURSTSIZE_16;
>> +
>> +	ch_regs->ahub_fifo_ctrl &= ~fifo_mask;
>> +	ch_regs->ahub_fifo_ctrl |= ADMA_FIFO_DEFAULT_SIZE << fifo_shift;
>> +	ch_regs->config &= ~ADMA_CH_CONFIG_BURST_SIZE_MASK;
>> +	ch_regs->config |= burst_size << ADMA_CH_CONFIG_BURST_SIZE_SHIFT;
>> +	ch_regs->ctrl &= ~(ctrl_mask | ADMA_CH_CTRL_TRANSFER_DIRECTION_MASK);
>> +	ch_regs->ctrl |= ctrl;
>> +
>> +	return -EINVAL;
> ??

Thanks. That's an error. Will fix.

>> +static int tegra_adma_pm_suspend(struct device *dev)
>> +{
>> +	struct tegra_dma *tdma = dev_get_drvdata(dev);
>> +	int i;
>> +	int ret;
>> +
>> +	ret = pm_runtime_get_sync(dev);
> why is this required :)

To ensure that the clocks are enabled before the registers are read.
This function saves the dma context before suspend, in case the hardware
state is lost.

>> +static int tegra_adma_pm_resume(struct device *dev)
>> +{
>> +	struct tegra_dma *tdma = dev_get_drvdata(dev);
>> +	int i;
>> +	int ret;
>> +
>> +	ret = pm_runtime_get_sync(dev);
> and this

Same here.

Cheers
Jon
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