Re: [PATCH V2 2/2] dmaengine: Add driver for IMG MDC

[Vinod Koul]

On Fri, Nov 14, 2014 at 01:59:43PM -0800, Andrew Bresticker wrote:
> +static inline unsigned int to_mdc_width(enum dma_slave_buswidth bw)
> +{
> +	switch (bw) {
> +	case DMA_SLAVE_BUSWIDTH_1_BYTE:
> +		return 0;
> +	case DMA_SLAVE_BUSWIDTH_2_BYTES:
> +		return 1;
> +	case DMA_SLAVE_BUSWIDTH_4_BYTES:
> +		return 2;
> +	case DMA_SLAVE_BUSWIDTH_8_BYTES:
> +		return 3;
ffs()?

> +	default:
> +		return 2;
for slave cases default makes little sense, better to return error?

> +	}
> +}
> +
> +static void mdc_list_desc_config(struct mdc_chan *mchan,
> +				 struct mdc_hw_list_desc *ldesc,
> +				 enum dma_transfer_direction dir,
> +				 dma_addr_t src, dma_addr_t dst, size_t len)
> +{
> +	struct mdc_dma *mdma = mchan->mdma;
> +	unsigned int max_burst, burst_size;
> +
> +	ldesc->gen_conf = MDC_GENERAL_CONFIG_IEN | MDC_GENERAL_CONFIG_LIST_IEN |
> +		MDC_GENERAL_CONFIG_LEVEL_INT | MDC_GENERAL_CONFIG_PHYSICAL_W |
> +		MDC_GENERAL_CONFIG_PHYSICAL_R;
> +	ldesc->readport_conf =
> +		(mchan->thread << MDC_READ_PORT_CONFIG_STHREAD_SHIFT) |
> +		(mchan->thread << MDC_READ_PORT_CONFIG_RTHREAD_SHIFT) |
> +		(mchan->thread << MDC_READ_PORT_CONFIG_WTHREAD_SHIFT);
> +	ldesc->read_addr = src;
> +	ldesc->write_addr = dst;
> +	ldesc->xfer_size = len - 1;
> +	ldesc->node_addr = 0;
> +	ldesc->cmds_done = 0;
> +	ldesc->ctrl_status = MDC_CONTROL_AND_STATUS_LIST_EN |
> +		MDC_CONTROL_AND_STATUS_EN;
> +	ldesc->next_desc = NULL;
> +
> +	if ((dst % mdma->bus_width == 0) && (src % mdma->bus_width == 0))
> +		max_burst = mdma->bus_width * mdma->max_burst_mult;
> +	else
> +		max_burst = mdma->bus_width * (mdma->max_burst_mult - 1);
sounds like you should use something like ALIGN ?

> +
> +	if (dir == DMA_MEM_TO_DEV) {
> +		ldesc->gen_conf |= MDC_GENERAL_CONFIG_INC_R |
> +			((fls(mdma->bus_width) - 1) <<
bus_width calculation is repeated quite few times, would help readability if
we hanlde this in macro. Also this be using src/dstn_addr_widths based on
direction passed

> +			 MDC_GENERAL_CONFIG_WIDTH_R_SHIFT) |
> +			(to_mdc_width(mchan->config.dst_addr_width) <<
> +			 MDC_GENERAL_CONFIG_WIDTH_W_SHIFT);
and a macro for this calculation, which take args for different cases would
help a lot!
> +		ldesc->readport_conf |= MDC_READ_PORT_CONFIG_DREQ_ENABLE;
> +		burst_size = min(max_burst, mchan->config.dst_maxburst *
> +				 mchan->config.dst_addr_width);
> +	} else if (dir == DMA_DEV_TO_MEM) {
> +		ldesc->gen_conf |= MDC_GENERAL_CONFIG_INC_W |
> +			(to_mdc_width(mchan->config.src_addr_width) <<
> +			 MDC_GENERAL_CONFIG_WIDTH_R_SHIFT) |
> +			((fls(mdma->bus_width) - 1) <<
> +			 MDC_GENERAL_CONFIG_WIDTH_W_SHIFT);
> +		ldesc->readport_conf |= MDC_READ_PORT_CONFIG_DREQ_ENABLE;
> +		burst_size = min(max_burst, mchan->config.src_maxburst *
> +				 mchan->config.src_addr_width);
> +	} else {
DEV_TO_DEV too?
> +		ldesc->gen_conf |= MDC_GENERAL_CONFIG_INC_R |
> +			MDC_GENERAL_CONFIG_INC_W |
> +			((fls(mdma->bus_width) - 1) <<
> +			 MDC_GENERAL_CONFIG_WIDTH_R_SHIFT) |
> +			((fls(mdma->bus_width) - 1) <<
> +			 MDC_GENERAL_CONFIG_WIDTH_W_SHIFT);
> +		burst_size = max_burst;
btw this piece is very hard to read, please do improve upon

> +static struct dma_async_tx_descriptor *mdc_prep_dma_memcpy(
> +	struct dma_chan *chan, dma_addr_t dest, dma_addr_t src, size_t len,
> +	unsigned long flags)
> +{
> +	struct mdc_chan *mchan = to_mdc_chan(chan);
> +	struct mdc_dma *mdma = mchan->mdma;
> +	struct mdc_tx_desc *mdesc;
> +	struct mdc_hw_list_desc *curr, *prev = NULL;
> +	dma_addr_t curr_phys, prev_phys;
> +
> +	if (!len)
> +		return NULL;
> +
> +	mdesc = kzalloc(sizeof(*mdesc), GFP_NOWAIT);
> +	if (!mdesc)
> +		return NULL;
> +	mdesc->chan = mchan;
> +	mdesc->list_xfer_size = len;
> +
> +	while (len > 0) {
> +		size_t xfer_size;
> +
> +		curr = dma_pool_alloc(mdma->desc_pool, GFP_NOWAIT, &curr_phys);
> +		if (!curr)
> +			goto free_desc;
> +
> +		if (prev) {
> +			prev->node_addr = curr_phys;
> +			prev->next_desc = curr;
> +		} else {
> +			mdesc->list_phys = curr_phys;
> +			mdesc->list = curr;
> +		}
> +
> +		xfer_size = min_t(size_t, mdma->max_xfer_size, len);
> +
> +		mdc_list_desc_config(mchan, curr, DMA_MEM_TO_MEM, src, dest,
> +				     xfer_size);
and this depends on dma_slave_config being set, which shouldn't be the case
for memcpy

> +static enum dma_status mdc_tx_status(struct dma_chan *chan,
> +	dma_cookie_t cookie, struct dma_tx_state *txstate)
> +{
> +	struct mdc_chan *mchan = to_mdc_chan(chan);
> +	struct mdc_tx_desc *mdesc;
> +	struct virt_dma_desc *vd;
> +	unsigned long flags;
> +	size_t bytes = 0;
> +	int ret;
> +
> +	ret = dma_cookie_status(chan, cookie, txstate);
> +	if (ret == DMA_COMPLETE)
> +		return ret;
> +
you should check txstate before proceeding. It can be null too

> +
> +static int mdc_slave_config(struct dma_chan *chan,
> +			    struct dma_slave_config *config)
> +{
> +	struct mdc_chan *mchan = to_mdc_chan(chan);
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&mchan->vc.lock, flags);
> +	if (config->direction == DMA_MEM_TO_DEV) {
> +		config->dst_addr_width = min(config->dst_addr_width,
> +					     mchan->mdma->bus_width);
> +	} else {
> +		config->src_addr_width = min(config->src_addr_width,
> +					     mchan->mdma->bus_width);
direction field is deprecated pls don't use that. Use the prep_xx direction
argument instead


> +static int mdc_dma_remove(struct platform_device *pdev)
> +{
> +	struct mdc_dma *mdma = platform_get_drvdata(pdev);
> +
> +	of_dma_controller_free(pdev->dev.of_node);
> +	dma_async_device_unregister(&mdma->dma_dev);
> +	clk_disable_unprepare(mdma->clk);
you need to call devm_irq_free() explicitly and also ensure you kill your
tasklet and syncronize irq()

Plus a rebase on Maxime's series which will be merged in required

-- 
~Vinod
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