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Date: Fri, 11 May 2018 16:52:25 +0530
From: Vinod Koul <vkoul@...nel.org>
To: Baolin Wang <baolin.wang@...aro.org>
Cc: dan.j.williams@...el.com, vinod.koul@...el.com,
eric.long@...eadtrum.com, broonie@...nel.org, lars@...afoo.de,
dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/2] dmaengine: sprd: Add Spreadtrum DMA configuration
On 09-05-18, 19:12, Baolin Wang wrote:
> +/*
> + * struct sprd_dma_config - DMA configuration structure
> + * @cfg: dma slave channel runtime config
> + * @src_addr: the source physical address
> + * @dst_addr: the destination physical address
> + * @block_len: specify one block transfer length
> + * @transcation_len: specify one transcation transfer length
> + * @src_step: source transfer step
> + * @dst_step: destination transfer step
> + * @wrap_ptr: wrap pointer address, once the transfer address reaches the
> + * 'wrap_ptr', the next transfer address will jump to the 'wrap_to' address.
> + * @wrap_to: wrap jump to address
> + * @req_mode: specify the DMA request mode
> + * @int_mode: specify the DMA interrupt type
> + */
> +struct sprd_dma_config {
> + struct dma_slave_config cfg;
> + phys_addr_t src_addr;
> + phys_addr_t dst_addr;
these are already in cfg so why duplicate, same for few more here.
> +static enum sprd_dma_datawidth
> +sprd_dma_get_datawidth(enum dma_slave_buswidth buswidth)
> +{
> + switch (buswidth) {
> + case DMA_SLAVE_BUSWIDTH_1_BYTE:
> + return SPRD_DMA_DATAWIDTH_1_BYTE;
> +
> + case DMA_SLAVE_BUSWIDTH_2_BYTES:
> + return SPRD_DMA_DATAWIDTH_2_BYTES;
> +
> + case DMA_SLAVE_BUSWIDTH_4_BYTES:
> + return SPRD_DMA_DATAWIDTH_4_BYTES;
> +
> + case DMA_SLAVE_BUSWIDTH_8_BYTES:
> + return SPRD_DMA_DATAWIDTH_8_BYTES;
> +
> + default:
> + return SPRD_DMA_DATAWIDTH_4_BYTES;
what is the logic of translation here, sometime you might be able to do that
with logical operators, see other drivers..
> + }
> +}
> +
> +static u32 sprd_dma_get_step(enum dma_slave_buswidth buswidth)
> +{
> + switch (buswidth) {
> + case DMA_SLAVE_BUSWIDTH_1_BYTE:
> + return SPRD_DMA_BYTE_STEP;
> +
> + case DMA_SLAVE_BUSWIDTH_2_BYTES:
> + return SPRD_DMA_SHORT_STEP;
> +
> + case DMA_SLAVE_BUSWIDTH_4_BYTES:
> + return SPRD_DMA_WORD_STEP;
> +
> + case DMA_SLAVE_BUSWIDTH_8_BYTES:
> + return SPRD_DMA_DWORD_STEP;
> +
> + default:
> + return SPRD_DMA_DWORD_STEP;
> + }
here as well
> +}
> +
> +static int sprd_dma_config(struct dma_chan *chan, struct sprd_dma_desc *sdesc,
> + struct sprd_dma_config *slave_cfg)
> +{
> + struct sprd_dma_dev *sdev = to_sprd_dma_dev(chan);
> + struct sprd_dma_chn *schan = to_sprd_dma_chan(chan);
> + struct sprd_dma_chn_hw *hw = &sdesc->chn_hw;
> + u32 fix_mode = 0, fix_en = 0, wrap_en = 0, wrap_mode = 0;
> + u32 src_datawidth, dst_datawidth;
> +
> + if (slave_cfg->cfg.slave_id)
> + schan->dev_id = slave_cfg->cfg.slave_id;
> +
> + hw->cfg = SPRD_DMA_DONOT_WAIT_BDONE << SPRD_DMA_WAIT_BDONE_OFFSET;
> + hw->wrap_ptr = (u32)((slave_cfg->wrap_ptr & SPRD_DMA_LOW_ADDR_MASK) |
why cast?
> + ((slave_cfg->src_addr >> SPRD_DMA_HIGH_ADDR_OFFSET) &
> + SPRD_DMA_HIGH_ADDR_MASK));
more readable would be:
temp = slave_cfg->wrap_ptr & SPRD_DMA_LOW_ADDR_MASK;
temp |= slave_cfg->src_addr >> SPRD_DMA_HIGH_ADDR_OFFSET;
temp &= SPRD_DMA_HIGH_ADDR_MASK;
and then assign... could help readability in few places...
> + hw->wrap_to = (u32)((slave_cfg->wrap_to & SPRD_DMA_LOW_ADDR_MASK) |
> + ((slave_cfg->dst_addr >> SPRD_DMA_HIGH_ADDR_OFFSET) &
> + SPRD_DMA_HIGH_ADDR_MASK));
> +
> + hw->src_addr = (u32)(slave_cfg->src_addr & SPRD_DMA_LOW_ADDR_MASK);
> + hw->des_addr = (u32)(slave_cfg->dst_addr & SPRD_DMA_LOW_ADDR_MASK);
> +
> + if ((slave_cfg->src_step != 0 && slave_cfg->dst_step != 0)
> + || (slave_cfg->src_step | slave_cfg->dst_step) == 0) {
> + fix_en = 0;
> + } else {
> + fix_en = 1;
> + if (slave_cfg->src_step)
> + fix_mode = 1;
> + else
> + fix_mode = 0;
> + }
> +
> + if (slave_cfg->wrap_ptr && slave_cfg->wrap_to) {
> + wrap_en = 1;
> + if (slave_cfg->wrap_to == slave_cfg->src_addr) {
> + wrap_mode = 0;
> + } else if (slave_cfg->wrap_to == slave_cfg->dst_addr) {
> + wrap_mode = 1;
> + } else {
> + dev_err(sdev->dma_dev.dev, "invalid wrap mode\n");
> + return -EINVAL;
> + }
> + }
> +
> + hw->intc = slave_cfg->int_mode | SPRD_DMA_CFG_ERR_INT_EN;
> +
> + src_datawidth = sprd_dma_get_datawidth(slave_cfg->cfg.src_addr_width);
> + dst_datawidth = sprd_dma_get_datawidth(slave_cfg->cfg.dst_addr_width);
> + hw->frg_len = src_datawidth << SPRD_DMA_SRC_DATAWIDTH_OFFSET |
> + dst_datawidth << SPRD_DMA_DES_DATAWIDTH_OFFSET |
> + slave_cfg->req_mode << SPRD_DMA_REQ_MODE_OFFSET |
> + wrap_mode << SPRD_DMA_WRAP_SEL_OFFSET |
> + wrap_en << SPRD_DMA_WRAP_EN_OFFSET |
> + fix_mode << SPRD_DMA_FIX_SEL_OFFSET |
> + fix_en << SPRD_DMA_FIX_EN_OFFSET |
> + (slave_cfg->cfg.src_maxburst & SPRD_DMA_FRG_LEN_MASK);
sorry this is not at all readable...
> +static struct dma_async_tx_descriptor *
> +sprd_dma_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
> + unsigned int sglen, enum dma_transfer_direction dir,
> + unsigned long flags, void *context)
> +{
> + struct sprd_dma_chn *schan = to_sprd_dma_chan(chan);
> + struct sprd_dma_config *slave_cfg = &schan->slave_cfg;
> + struct sprd_dma_desc *sdesc;
> + struct scatterlist *sg;
> + int ret, i;
> +
> + /* TODO: now we only support one sg for each DMA configuration. */
thats a SW limit right and you will fix it later?
> + if (!is_slave_direction(dir) || sglen > 1)
> + return NULL;
> +
> + sdesc = kzalloc(sizeof(*sdesc), GFP_NOWAIT);
> + if (!sdesc)
> + return NULL;
> +
> + for_each_sg(sgl, sg, sglen, i) {
> + if (dir == DMA_MEM_TO_DEV) {
> + slave_cfg->src_addr = sg_dma_address(sg);
> + slave_cfg->dst_addr = slave_cfg->cfg.dst_addr;
> + slave_cfg->src_step =
> + sprd_dma_get_step(slave_cfg->cfg.src_addr_width);
> + slave_cfg->dst_step = SPRD_DMA_NONE_STEP;
> + } else {
> + slave_cfg->src_addr = slave_cfg->cfg.src_addr;
> + slave_cfg->dst_addr = sg_dma_address(sg);
> + slave_cfg->src_step = SPRD_DMA_NONE_STEP;
> + slave_cfg->dst_step =
> + sprd_dma_get_step(slave_cfg->cfg.dst_addr_width);
use a helper for filling this and passing right values for each case?
--
~Vinod
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