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SubjectRe: [RFC PATCH] dmaengine: sh: Correct src_addr_widths/dst_addr_widths bitmask setting
On Sun, Sep 17, 2017 at 04:45:39PM +0200, Stefan Brüns wrote:
> Obviously, the current value for the burst widths are wrong, and if this
> value is retrieved from some other subsystem using dma_get_slave_caps,
> it will wrongly assume burst width of e.g. 3 bytes are supported.
>
> Each bit in the bitmask corresponds to a supported width, but it uses
> an encoding of BIT(<widths>), not BIT(log2<widths>), as it must be able
> to encode a width of 3 bytes.
>
> The corollary is, it is not possible to encode either a width of 32 or
> 64 bytes, as the field has a size of 32 bits, and only a subset of the
> controller capabilities can be exposed.

well the right way would have been to fix this in the core by extending the
src/dst_addr_widths. I am sending a patch for that. please use that and
update this

>
> Signed-off-by: Stefan Brüns <stefan.bruens@rwth-aachen.de>
> ---
> drivers/dma/sh/rcar-dmac.c | 14 ++++++++++----
> drivers/dma/sh/shdmac.c | 13 +++++++++----
> drivers/dma/sh/usb-dmac.c | 9 ++++++---
> 3 files changed, 25 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c
> index 2b2c7db3e480..768076caccfd 100644
> --- a/drivers/dma/sh/rcar-dmac.c
> +++ b/drivers/dma/sh/rcar-dmac.c
> @@ -1734,10 +1734,16 @@ static int rcar_dmac_parse_of(struct device *dev, struct rcar_dmac *dmac)
>
> static int rcar_dmac_probe(struct platform_device *pdev)
> {
> - const enum dma_slave_buswidth widths = DMA_SLAVE_BUSWIDTH_1_BYTE |
> - DMA_SLAVE_BUSWIDTH_2_BYTES | DMA_SLAVE_BUSWIDTH_4_BYTES |
> - DMA_SLAVE_BUSWIDTH_8_BYTES | DMA_SLAVE_BUSWIDTH_16_BYTES |
> - DMA_SLAVE_BUSWIDTH_32_BYTES | DMA_SLAVE_BUSWIDTH_64_BYTES;
> + /*
> + * FIXME: Controller supports DMA_SLAVE_BUSWIDTH_32_BYTES
> + * and DMA_SLAVE_BUSWIDTH_64_BYTES,
> + * but this overflows the u32 src/dst_addr_widths fields
> + */
> + const u32 widths = BIT(DMA_SLAVE_BUSWIDTH_1_BYTE) |
> + BIT(DMA_SLAVE_BUSWIDTH_2_BYTES) |
> + BIT(DMA_SLAVE_BUSWIDTH_4_BYTES) |
> + BIT(DMA_SLAVE_BUSWIDTH_8_BYTES) |
> + BIT(DMA_SLAVE_BUSWIDTH_16_BYTES);
> unsigned int channels_offset = 0;
> struct dma_device *engine;
> struct rcar_dmac *dmac;
> diff --git a/drivers/dma/sh/shdmac.c b/drivers/dma/sh/shdmac.c
> index c94ffab0d25c..bf35b5588b11 100644
> --- a/drivers/dma/sh/shdmac.c
> +++ b/drivers/dma/sh/shdmac.c
> @@ -679,10 +679,15 @@ MODULE_DEVICE_TABLE(of, sh_dmae_of_match);
>
> static int sh_dmae_probe(struct platform_device *pdev)
> {
> - const enum dma_slave_buswidth widths =
> - DMA_SLAVE_BUSWIDTH_1_BYTE | DMA_SLAVE_BUSWIDTH_2_BYTES |
> - DMA_SLAVE_BUSWIDTH_4_BYTES | DMA_SLAVE_BUSWIDTH_8_BYTES |
> - DMA_SLAVE_BUSWIDTH_16_BYTES | DMA_SLAVE_BUSWIDTH_32_BYTES;
> + /*
> + * FIXME: Controller supports DMA_SLAVE_BUSWIDTH_32_BYTES
> + * but this overflows the u32 src/dst_addr_widths fields
> + */
> + const u32 widths = BIT(DMA_SLAVE_BUSWIDTH_1_BYTE) |
> + BIT(DMA_SLAVE_BUSWIDTH_2_BYTES) |
> + BIT(DMA_SLAVE_BUSWIDTH_4_BYTES) |
> + BIT(DMA_SLAVE_BUSWIDTH_8_BYTES) |
> + BIT(DMA_SLAVE_BUSWIDTH_16_BYTES);
> const struct sh_dmae_pdata *pdata;
> unsigned long chan_flag[SH_DMAE_MAX_CHANNELS] = {};
> int chan_irq[SH_DMAE_MAX_CHANNELS];
> diff --git a/drivers/dma/sh/usb-dmac.c b/drivers/dma/sh/usb-dmac.c
> index 31a145154e9f..0ac7e842b70c 100644
> --- a/drivers/dma/sh/usb-dmac.c
> +++ b/drivers/dma/sh/usb-dmac.c
> @@ -768,7 +768,6 @@ static int usb_dmac_parse_of(struct device *dev, struct usb_dmac *dmac)
>
> static int usb_dmac_probe(struct platform_device *pdev)
> {
> - const enum dma_slave_buswidth widths = USB_DMAC_SLAVE_BUSWIDTH;
> struct dma_device *engine;
> struct usb_dmac *dmac;
> struct resource *mem;
> @@ -837,8 +836,12 @@ static int usb_dmac_probe(struct platform_device *pdev)
>
> engine->dev = &pdev->dev;
>
> - engine->src_addr_widths = widths;
> - engine->dst_addr_widths = widths;
> + /*
> + * FIXME: The controller supports a width of USB_DMAC_SLAVE_BUSWIDTH,
> + * i.e. 32 bytes, but BIT(32) overflows the u32 bitmask fields.
> + */
> + engine->src_addr_widths = 0;
> + engine->dst_addr_widths = 0;
> engine->directions = BIT(DMA_MEM_TO_DEV) | BIT(DMA_DEV_TO_MEM);
> engine->residue_granularity = DMA_RESIDUE_GRANULARITY_BURST;
>
> --
> 2.14.1
>
> --
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--
~Vinod

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