On Thu, Feb 26, 2015 at 12:43:33PM +0000, Zubair Lutfullah Kakakhel wrote:
> +/* Per-channel registers. */
> +#define JZ_DMA_REG_DSA(n) (0x00 + (n) * 0x20)
> +#define JZ_DMA_REG_DTA(n) (0x04 + (n) * 0x20)
> +#define JZ_DMA_REG_DTC(n) (0x08 + (n) * 0x20)
> +#define JZ_DMA_REG_DRT(n) (0x0c + (n) * 0x20)
> +#define JZ_DMA_REG_DCS(n) (0x10 + (n) * 0x20)
> +#define JZ_DMA_REG_DCM(n) (0x14 + (n) * 0x20)
> +#define JZ_DMA_REG_DDA(n) (0x18 + (n) * 0x20)
> +#define JZ_DMA_REG_DSD(n) (0x1c + (n) * 0x20)
shouldn't this be a macro rather than copy paste n * 0x20
> +
> +#define JZ_DMA_DMAC_DMAE BIT(0)
> +#define JZ_DMA_DMAC_AR BIT(2)
> +#define JZ_DMA_DMAC_HLT BIT(3)
> +#define JZ_DMA_DMAC_FMSC BIT(31)
> +
> +#define JZ_DMA_DRT_AUTO 0x8
not consistent in BIT?
> +static struct jz4780_dma_desc *jz4780_dma_desc_alloc(
> + struct jz4780_dma_chan *jzchan, unsigned int count,
> + enum dma_transaction_type type)
> +{
> + struct jz4780_dma_desc *desc;
> +
> + if (count > JZ_DMA_MAX_DESC)
> + return NULL;
> +
> + desc = kzalloc(sizeof(*desc), GFP_ATOMIC);
GFP_NOWAIT pls
> + if (!desc)
> + return NULL;
> +
> + desc->desc = dma_pool_alloc(jzchan->desc_pool, GFP_ATOMIC,
ditto
> +static uint32_t jz4780_dma_width(enum dma_slave_buswidth width)
> +{
> + switch (width) {
> + case DMA_SLAVE_BUSWIDTH_1_BYTE:
> + return JZ_DMA_WIDTH_8_BIT;
> + case DMA_SLAVE_BUSWIDTH_2_BYTES:
> + return JZ_DMA_WIDTH_16_BIT;
these are same as dmaengine defines so should this be:
case DMA_SLAVE_BUSWIDTH_1_BYTE:
case DMA_SLAVE_BUSWIDTH_2_BYTES:
return width;
> + default:
> + return JZ_DMA_WIDTH_32_BIT;
> + }
> +}
> +
> +static uint32_t jz4780_dma_transfer_size(unsigned long val, int *ord)
> +{
> + *ord = ffs(val) - 1;
> +
> + /* 8 byte transfer sizes unsupported so fall back on 4. */
okay falling back is not a good idea, same applies for default in
jz4780_dma_width(). The slave dma parameters are match with devices, so
programming something which you dont support, falling back or using defaults
is not a good idea
> + default:
> + WARN_ON(1);
> + return -1; /* Can never happen. See previous comment */
-1?? what happened to kernel error codes?
> + }
> +}
> +
> +static void jz4780_dma_setup_hwdesc(struct jz4780_dma_chan *jzchan,
> + struct jz4780_dma_hwdesc *desc, dma_addr_t addr, size_t len)
> +{
> + struct dma_slave_config *config = &jzchan->config;
> + uint32_t width, maxburst, tsz;
> + int ord;
> +
> + if (config->direction == DMA_MEM_TO_DEV) {
this is a wrong idea, use the direction from the prep_ call
> +static enum dma_status jz4780_dma_tx_status(struct dma_chan *chan,
> + dma_cookie_t cookie, struct dma_tx_state *txstate)
> +{
> + struct jz4780_dma_chan *jzchan = to_jz4780_dma_chan(chan);
> + struct virt_dma_desc *vdesc;
> + enum dma_status status;
> + unsigned long flags;
> +
> + status = dma_cookie_status(chan, cookie, txstate);
> + if (status == DMA_COMPLETE)
or if the txstate is NULL
--
~Vinod
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