linux-kernel - Re: [PATCH 03/18] dmaengine: st_fdma: Add STMicroelectronics FDMA engine driver support

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Message-ID: <20160426165622.GR2274@localhost>
Date:	Tue, 26 Apr 2016 22:26:22 +0530
From:	Vinod Koul <vinod.koul@...el.com>
To:	Peter Griffin <peter.griffin@...aro.org>
Cc:	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	srinivas.kandagatla@...il.com, maxime.coquelin@...com,
	patrice.chotard@...com, lee.jones@...aro.org,
	dmaengine@...r.kernel.org, devicetree@...r.kernel.org,
	arnd@...db.de, broonie@...nel.org, ludovic.barre@...com
Subject: Re: [PATCH 03/18] dmaengine: st_fdma: Add STMicroelectronics FDMA
 engine driver support

On Thu, Apr 21, 2016 at 12:04:20PM +0100, Peter Griffin wrote:

> +	if (!atomic_read(&fchan->fdev->fw_loaded)) {
> +		dev_err(fchan->fdev->dev, "%s: fdma fw not loaded\n", __func__);
> +		return NULL;
> +	}

so who is loading the fw and setting fw_loaded, it is not set in this patch?

> +	if (direction == DMA_DEV_TO_MEM) {
> +		fchan->cfg.req_ctrl &= ~REQ_CTRL_WNR;
> +		maxburst = fchan->scfg.src_maxburst;
> +		width = fchan->scfg.src_addr_width;
> +		addr = fchan->scfg.src_addr;
> +	} else if (direction == DMA_MEM_TO_DEV) {
> +		fchan->cfg.req_ctrl |= REQ_CTRL_WNR;
> +		maxburst = fchan->scfg.dst_maxburst;
> +		width = fchan->scfg.dst_addr_width;
> +		addr = fchan->scfg.dst_addr;
> +	} else {
> +		return -EINVAL;
> +	}

switch please

> +
> +	fchan->cfg.req_ctrl &= ~REQ_CTRL_OPCODE_MASK;
> +	if (width == DMA_SLAVE_BUSWIDTH_1_BYTE)
> +		fchan->cfg.req_ctrl |= REQ_CTRL_OPCODE_LD_ST1;
> +	else if (width == DMA_SLAVE_BUSWIDTH_2_BYTES)
> +		fchan->cfg.req_ctrl |= REQ_CTRL_OPCODE_LD_ST2;
> +	else if (width == DMA_SLAVE_BUSWIDTH_4_BYTES)
> +		fchan->cfg.req_ctrl |= REQ_CTRL_OPCODE_LD_ST4;
> +	else if (width == DMA_SLAVE_BUSWIDTH_8_BYTES)
> +		fchan->cfg.req_ctrl |= REQ_CTRL_OPCODE_LD_ST8;
> +	else
> +		return -EINVAL;

here as well

> +static void fill_hw_node(struct st_fdma_hw_node *hw_node,
> +			struct st_fdma_chan *fchan,
> +			enum dma_transfer_direction direction)
> +{
> +
> +	if (direction == DMA_MEM_TO_DEV) {
> +		hw_node->control |= NODE_CTRL_SRC_INCR;
> +		hw_node->control |= NODE_CTRL_DST_STATIC;
> +		hw_node->daddr = fchan->cfg.dev_addr;
> +	} else {
> +		hw_node->control |= NODE_CTRL_SRC_STATIC;
> +		hw_node->control |= NODE_CTRL_DST_INCR;
> +		hw_node->saddr = fchan->cfg.dev_addr;
> +	}

empty line here at other places too. The code looks very compressed and bit
harder to read overall

> +	fdesc = st_fdma_alloc_desc(fchan, sg_len);
> +	if (!fdesc) {
> +		dev_err(fchan->fdev->dev, "no memory for desc\n");
> +		return NULL;
> +	}
> +
> +	fdesc->iscyclic = false;
> +
> +	for_each_sg(sgl, sg, sg_len, i) {
> +		hw_node = fdesc->node[i].desc;
> +
> +		hw_node->next = fdesc->node[(i + 1) % sg_len].pdesc;
> +		hw_node->control = NODE_CTRL_REQ_MAP_DREQ(fchan->dreq_line);
> +
> +		fill_hw_node(hw_node, fchan, direction);
> +
> +		if (direction == DMA_MEM_TO_DEV)
> +			hw_node->saddr = sg_dma_address(sg);
> +		else
> +			hw_node->daddr = sg_dma_address(sg);
> +
> +		hw_node->nbytes = sg_dma_len(sg);
> +		hw_node->generic.length = sg_dma_len(sg);
> +	}
> +
> +	/* interrupt at end of last node */
> +	hw_node->control |= NODE_CTRL_INT_EON;
> +
> +	return vchan_tx_prep(&fchan->vchan, &fdesc->vdesc, flags);

bunch of this seems similar to cyclic case, can you create common setup
routine for these, anyway cyclic is a special cases of slave_sg

> +
> +	ret = dma_cookie_status(chan, cookie, txstate);
> +	if (ret == DMA_COMPLETE)
> +		return ret;
> +
> +	if (!txstate)
> +		return fchan->status;

why channel status, query is for descriptor

> +static int st_fdma_remove(struct platform_device *pdev)
> +{
> +	struct st_fdma_dev *fdev = platform_get_drvdata(pdev);
> +
> +	st_fdma_clk_disable(fdev);

and you irq is still enabled and tasklets can be scheduled!!

-- 
~Vinod