mirror of https://gitee.com/openkylin/linux.git
dmaengine: dma-jz4780: Use 4-word descriptors
The only information we use in the 8-word version of the hardware DMA descriptor that is not present in the 4-word version is the transfer type, aka. the ID of the source or recipient device. Since the transfer type will never change for a DMA channel in use, we can just set it once for all in the corresponding DMA register before starting any transfer. This has several benefits: * the driver will handle twice as many hardware DMA descriptors; * the driver is closer to support the JZ4740, which only supports 4-word hardware DMA descriptors; * the JZ4770 SoC needs the transfer type to be set in the corresponding DMA register anyway, even if 8-word descriptors are in use. Signed-off-by: Paul Cercueil <paul@crapouillou.net> Tested-by: Mathieu Malaterre <malat@debian.org> Reviewed-by: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com> Signed-off-by: Vinod Koul <vkoul@kernel.org>
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@ -95,17 +95,12 @@
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* @dtc: transfer count (number of blocks of the transfer size specified in DCM
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* to transfer) in the low 24 bits, offset of the next descriptor from the
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* descriptor base address in the upper 8 bits.
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* @sd: target/source stride difference (in stride transfer mode).
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* @drt: request type
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*/
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struct jz4780_dma_hwdesc {
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uint32_t dcm;
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uint32_t dsa;
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uint32_t dta;
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uint32_t dtc;
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uint32_t sd;
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uint32_t drt;
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uint32_t reserved[2];
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};
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/* Size of allocations for hardware descriptor blocks. */
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@ -281,7 +276,6 @@ static int jz4780_dma_setup_hwdesc(struct jz4780_dma_chan *jzchan,
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desc->dcm = JZ_DMA_DCM_SAI;
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desc->dsa = addr;
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desc->dta = config->dst_addr;
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desc->drt = jzchan->transfer_type;
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width = config->dst_addr_width;
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maxburst = config->dst_maxburst;
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@ -289,7 +283,6 @@ static int jz4780_dma_setup_hwdesc(struct jz4780_dma_chan *jzchan,
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desc->dcm = JZ_DMA_DCM_DAI;
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desc->dsa = config->src_addr;
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desc->dta = addr;
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desc->drt = jzchan->transfer_type;
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width = config->src_addr_width;
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maxburst = config->src_maxburst;
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@ -434,9 +427,10 @@ static struct dma_async_tx_descriptor *jz4780_dma_prep_dma_memcpy(
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tsz = jz4780_dma_transfer_size(dest | src | len,
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&jzchan->transfer_shift);
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jzchan->transfer_type = JZ_DMA_DRT_AUTO;
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desc->desc[0].dsa = src;
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desc->desc[0].dta = dest;
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desc->desc[0].drt = JZ_DMA_DRT_AUTO;
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desc->desc[0].dcm = JZ_DMA_DCM_TIE | JZ_DMA_DCM_SAI | JZ_DMA_DCM_DAI |
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tsz << JZ_DMA_DCM_TSZ_SHIFT |
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JZ_DMA_WIDTH_32_BIT << JZ_DMA_DCM_SP_SHIFT |
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@ -491,9 +485,12 @@ static void jz4780_dma_begin(struct jz4780_dma_chan *jzchan)
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(jzchan->curr_hwdesc + 1) % jzchan->desc->count;
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}
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/* Use 8-word descriptors. */
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jz4780_dma_chn_writel(jzdma, jzchan->id,
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JZ_DMA_REG_DCS, JZ_DMA_DCS_DES8);
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/* Use 4-word descriptors. */
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jz4780_dma_chn_writel(jzdma, jzchan->id, JZ_DMA_REG_DCS, 0);
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/* Set transfer type. */
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jz4780_dma_chn_writel(jzdma, jzchan->id, JZ_DMA_REG_DRT,
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jzchan->transfer_type);
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/* Write descriptor address and initiate descriptor fetch. */
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desc_phys = jzchan->desc->desc_phys +
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@ -503,7 +500,7 @@ static void jz4780_dma_begin(struct jz4780_dma_chan *jzchan)
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/* Enable the channel. */
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jz4780_dma_chn_writel(jzdma, jzchan->id, JZ_DMA_REG_DCS,
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JZ_DMA_DCS_DES8 | JZ_DMA_DCS_CTE);
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JZ_DMA_DCS_CTE);
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}
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static void jz4780_dma_issue_pending(struct dma_chan *chan)
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