Re: [PATCH v3 08/15] dmaengine: dw: revisit data_width property

From: Vinod Koul
Date: Wed Apr 13 2016 - 11:53:04 EST

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On Fri, Mar 18, 2016 at 04:24:47PM +0200, Andy Shevchenko wrote:
> There are several changes are done here:
>
> - Convert the property to be in bytes
>
> Much more convenient than keeping encoded value.
>
> - Use one value for all AHB masters for now
>
> It seems in practice we have no controllers where masters have different
> data bus width, we still might return to distinct values when there is a use
> case.
>
> - Rename data_width to data-width in the device tree bindings.
>
> - While here, replace dwc_fast_ffs() by __ffs().
>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> ---
> Documentation/devicetree/bindings/dma/snps-dma.txt | 5 ++-
> arch/arc/boot/dts/abilis_tb10x.dtsi | 2 +-
> arch/arm/boot/dts/spear13xx.dtsi | 4 +--
> drivers/dma/dw/core.c | 40 +++-------------------
> drivers/dma/dw/platform.c | 10 +++---
> drivers/dma/dw/regs.h | 2 +-
> include/linux/platform_data/dma-dw.h | 5 ++-
> 7 files changed, 18 insertions(+), 50 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/dma/snps-dma.txt b/Documentation/devicetree/bindings/dma/snps-dma.txt
> index c99c1ff..eb48229 100644
> --- a/Documentation/devicetree/bindings/dma/snps-dma.txt
> +++ b/Documentation/devicetree/bindings/dma/snps-dma.txt
> @@ -13,8 +13,7 @@ Required properties:
> - chan_priority: priority of channels. 0 (default): increase from chan 0->n, 1:
> increase from chan n->0
> - block_size: Maximum block size supported by the controller
> -- data_width: Maximum data width supported by hardware per AHB master
> - (0 - 8bits, 1 - 16bits, ..., 5 - 256bits)
> +- data-width: Maximum data width supported by hardware (in bytes, power of 2)

You missed that binding are treated as ABI, see
Documentation/devicetree/bindings/ABI.txt

The driver should still work with older DT implementation, so you need to
keep support for that in driver and hence I don't see any benfit we would
get from doing both in driver!

>
>
> Optional properties:
> @@ -38,7 +37,7 @@ Example:
> chan_allocation_order = <1>;
> chan_priority = <1>;
> block_size = <0xfff>;
> - data_width = <3 3>;
> + data-width = <8>;
> };
>
> DMA clients connected to the Designware DMA controller must use the format
> diff --git a/arch/arc/boot/dts/abilis_tb10x.dtsi b/arch/arc/boot/dts/abilis_tb10x.dtsi
> index cfb5052..2f53bed 100644
> --- a/arch/arc/boot/dts/abilis_tb10x.dtsi
> +++ b/arch/arc/boot/dts/abilis_tb10x.dtsi
> @@ -112,7 +112,7 @@
> chan_allocation_order = <0>;
> chan_priority = <1>;
> block_size = <0x7ff>;
> - data_width = <2>;
> + data-width = <4>;
> clocks = <&ahb_clk>;
> clock-names = "hclk";
> };
> diff --git a/arch/arm/boot/dts/spear13xx.dtsi b/arch/arm/boot/dts/spear13xx.dtsi
> index 14594ce..474b66f 100644
> --- a/arch/arm/boot/dts/spear13xx.dtsi
> +++ b/arch/arm/boot/dts/spear13xx.dtsi
> @@ -117,7 +117,7 @@
> chan_priority = <1>;
> block_size = <0xfff>;
> dma-masters = <2>;
> - data_width = <3 3>;
> + data-width = <8>;
> };
>
> dma@eb000000 {
> @@ -133,7 +133,7 @@
> chan_allocation_order = <1>;
> chan_priority = <1>;
> block_size = <0xfff>;
> - data_width = <3 3>;
> + data-width = <8>;
> };
>
> fsmc: flash@b0000000 {
> diff --git a/drivers/dma/dw/core.c b/drivers/dma/dw/core.c
> index 4748df9..79dbfc3 100644
> --- a/drivers/dma/dw/core.c
> +++ b/drivers/dma/dw/core.c
> @@ -155,21 +155,6 @@ static void dwc_initialize(struct dw_dma_chan *dwc)
>
> /*----------------------------------------------------------------------*/
>
> -static inline unsigned int dwc_fast_ffs(unsigned long long v)
> -{
> - /*
> - * We can be a lot more clever here, but this should take care
> - * of the most common optimization.
> - */
> - if (!(v & 7))
> - return 3;
> - else if (!(v & 3))
> - return 2;
> - else if (!(v & 1))
> - return 1;
> - return 0;
> -}
> -
> static inline void dwc_dump_chan_regs(struct dw_dma_chan *dwc)
> {
> dev_err(chan2dev(&dwc->chan),
> @@ -703,7 +688,6 @@ dwc_prep_dma_memcpy(struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
> size_t offset;
> unsigned int src_width;
> unsigned int dst_width;
> - unsigned int data_width;
> u32 ctllo;
> u8 lms = DWC_LLP_LMS(dwc->m_master);
>
> @@ -718,10 +702,7 @@ dwc_prep_dma_memcpy(struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
>
> dwc->direction = DMA_MEM_TO_MEM;
>
> - data_width = dw->data_width[dwc->m_master];
> -
> - src_width = dst_width = min_t(unsigned int, data_width,
> - dwc_fast_ffs(src | dest | len));
> + src_width = dst_width = __ffs(dw->data_width | src | dest | len);
>
> ctllo = DWC_DEFAULT_CTLLO(chan)
> | DWC_CTLL_DST_WIDTH(dst_width)
> @@ -785,7 +766,6 @@ dwc_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
> dma_addr_t reg;
> unsigned int reg_width;
> unsigned int mem_width;
> - unsigned int data_width;
> unsigned int i;
> struct scatterlist *sg;
> size_t total_len = 0;
> @@ -811,8 +791,6 @@ dwc_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
> ctllo |= sconfig->device_fc ? DWC_CTLL_FC(DW_DMA_FC_P_M2P) :
> DWC_CTLL_FC(DW_DMA_FC_D_M2P);
>
> - data_width = dw->data_width[dwc->m_master];
> -
> for_each_sg(sgl, sg, sg_len, i) {
> struct dw_desc *desc;
> u32 len, dlen, mem;
> @@ -820,8 +798,7 @@ dwc_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
> mem = sg_dma_address(sg);
> len = sg_dma_len(sg);
>
> - mem_width = min_t(unsigned int,
> - data_width, dwc_fast_ffs(mem | len));
> + mem_width = __ffs(dw->data_width | mem | len);
>
> slave_sg_todev_fill_desc:
> desc = dwc_desc_get(dwc);
> @@ -867,8 +844,6 @@ slave_sg_todev_fill_desc:
> ctllo |= sconfig->device_fc ? DWC_CTLL_FC(DW_DMA_FC_P_P2M) :
> DWC_CTLL_FC(DW_DMA_FC_D_P2M);
>
> - data_width = dw->data_width[dwc->m_master];
> -
> for_each_sg(sgl, sg, sg_len, i) {
> struct dw_desc *desc;
> u32 len, dlen, mem;
> @@ -876,8 +851,7 @@ slave_sg_todev_fill_desc:
> mem = sg_dma_address(sg);
> len = sg_dma_len(sg);
>
> - mem_width = min_t(unsigned int,
> - data_width, dwc_fast_ffs(mem | len));
> + mem_width = __ffs(dw->data_width | mem | len);
>
> slave_sg_fromdev_fill_desc:
> desc = dwc_desc_get(dwc);
> @@ -1544,10 +1518,7 @@ int dw_dma_probe(struct dw_dma_chip *chip, struct dw_dma_platform_data *pdata)
> /* Get hardware configuration parameters */
> pdata->nr_channels = (dw_params >> DW_PARAMS_NR_CHAN & 7) + 1;
> pdata->nr_masters = (dw_params >> DW_PARAMS_NR_MASTER & 3) + 1;
> - for (i = 0; i < pdata->nr_masters; i++) {
> - pdata->data_width[i] =
> - (dw_params >> DW_PARAMS_DATA_WIDTH(i) & 3) + 2;
> - }
> + pdata->data_width = 4 << (dw_params >> DW_PARAMS_DATA_WIDTH(0) & 3);
> max_blk_size = dma_readl(dw, MAX_BLK_SIZE);
>
> /* Fill platform data with the default values */
> @@ -1569,8 +1540,7 @@ int dw_dma_probe(struct dw_dma_chip *chip, struct dw_dma_platform_data *pdata)
>
> /* Get hardware configuration parameters */
> dw->nr_masters = pdata->nr_masters;
> - for (i = 0; i < dw->nr_masters; i++)
> - dw->data_width[i] = pdata->data_width[i];
> + dw->data_width = pdata->data_width;
>
> /* Calculate all channel mask before DMA setup */
> dw->all_chan_mask = (1 << pdata->nr_channels) - 1;
> diff --git a/drivers/dma/dw/platform.c b/drivers/dma/dw/platform.c
> index 23616c5..4cf399d 100644
> --- a/drivers/dma/dw/platform.c
> +++ b/drivers/dma/dw/platform.c
> @@ -102,8 +102,8 @@ dw_dma_parse_dt(struct platform_device *pdev)
> {
> struct device_node *np = pdev->dev.of_node;
> struct dw_dma_platform_data *pdata;
> - u32 tmp, arr[DW_DMA_MAX_NR_MASTERS];
> u32 nr_channels;
> + u32 tmp;
>
> if (!np) {
> dev_err(&pdev->dev, "Missing DT data\n");
> @@ -138,10 +138,10 @@ dw_dma_parse_dt(struct platform_device *pdev)
> pdata->nr_masters = tmp;
> }
>
> - if (!of_property_read_u32_array(np, "data_width", arr,
> - pdata->nr_masters))
> - for (tmp = 0; tmp < pdata->nr_masters; tmp++)
> - pdata->data_width[tmp] = arr[tmp];
> + if (!of_property_read_u32(np, "data-width", &tmp))
> + pdata->data_width = tmp;
> + else if (!of_property_read_u32(np, "data_width", &tmp))
> + pdata->data_width = BIT(tmp & 0x07);
>
> return pdata;
> }
> diff --git a/drivers/dma/dw/regs.h b/drivers/dma/dw/regs.h
> index feb3a4a..d0f9173 100644
> --- a/drivers/dma/dw/regs.h
> +++ b/drivers/dma/dw/regs.h
> @@ -285,7 +285,7 @@ struct dw_dma {
>
> /* hardware configuration */
> unsigned char nr_masters;
> - unsigned char data_width[DW_DMA_MAX_NR_MASTERS];
> + unsigned char data_width;
> };
>
> static inline struct dw_dma_regs __iomem *__dw_regs(struct dw_dma *dw)
> diff --git a/include/linux/platform_data/dma-dw.h b/include/linux/platform_data/dma-dw.h
> index b881b97..09cf5c1 100644
> --- a/include/linux/platform_data/dma-dw.h
> +++ b/include/linux/platform_data/dma-dw.h
> @@ -42,8 +42,7 @@ struct dw_dma_slave {
> * @chan_priority: Set channel priority increasing from 0 to 7 or 7 to 0.
> * @block_size: Maximum block size supported by the controller
> * @nr_masters: Number of AHB masters supported by the controller
> - * @data_width: Maximum data width supported by hardware per AHB master
> - * (0 - 8bits, 1 - 16bits, ..., 5 - 256bits)
> + * @data_width: Maximum data width supported by hardware (in bytes, power of 2)
> */
> struct dw_dma_platform_data {
> unsigned int nr_channels;
> @@ -57,7 +56,7 @@ struct dw_dma_platform_data {
> unsigned char chan_priority;
> unsigned short block_size;
> unsigned char nr_masters;
> - unsigned char data_width[DW_DMA_MAX_NR_MASTERS];
> + unsigned char data_width;
> };
>
> #endif /* _PLATFORM_DATA_DMA_DW_H */
> --
> 2.7.0
>

--
~Vinod

Next message: Waiman Long: "Re: [PATCH] powerpc: introduce {cmp}xchg for u8 and u16"
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Next in thread: Andy Shevchenko: "Re: [PATCH v3 08/15] dmaengine: dw: revisit data_width property"
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