Re: [PATCH 04/10] dmaengine: sun6i: Enable additional burst lengths/widths on H3

Maxime Ripard
2017-09-04T08:01:01Z

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On Mon, Sep 04, 2017 at 12:40:55AM +0200, Stefan Brüns wrote:
> The H3 supports bursts lengths of 1, 4, 8 and 16 transfers, each with
> a width of 1, 2, 4 or 8 bytes.
>
> The register value for the the width is log2-encoded, change the
> conversion function to provide the correct value for width == 8.
>
> Signed-off-by: Stefan Brüns <stefan.bruens@rwth-aachen.de>
> ---
> drivers/dma/sun6i-dma.c | 12 +++++++++++-
> 1 file changed, 11 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/dma/sun6i-dma.c b/drivers/dma/sun6i-dma.c
> index c5644bd0f91a..335a8ec88b0b 100644
> --- a/drivers/dma/sun6i-dma.c
> +++ b/drivers/dma/sun6i-dma.c
> @@ -263,8 +263,12 @@ static inline s8 convert_burst(u32 maxburst)
> switch (maxburst) {
> case 1:
> return 0;
> + case 4:
> + return 1;
> case 8:
> return 2;
> + case 16:
> + return 3;
> default:
> return -EINVAL;
> }
> @@ -272,7 +276,7 @@ static inline s8 convert_burst(u32 maxburst)
>
> static inline s8 convert_buswidth(enum dma_slave_buswidth addr_width)
> {
> - return addr_width >> 1;
> + return ilog2(addr_width);
> }
>
> static size_t sun6i_get_chan_size(struct sun6i_pchan *pchan)
> @@ -1152,6 +1156,12 @@ static int sun6i_dma_probe(struct platform_device *pdev)
> BIT(DMA_SLAVE_BUSWIDTH_4_BYTES);
> sdc->src_burst_lengths = BIT(1) | BIT(8);
> sdc->dst_burst_lengths = BIT(1) | BIT(8);
> + if (sdc->cfg->dmac_variant == DMAC_VARIANT_H3) {
> + sdc->slave.src_addr_widths |= BIT(DMA_SLAVE_BUSWIDTH_8_BYTES);
> + sdc->slave.dst_addr_widths |= BIT(DMA_SLAVE_BUSWIDTH_8_BYTES);
> + sdc->src_burst_lengths |= BIT(4) | BIT(16);
> + sdc->dst_burst_lengths |= BIT(4) | BIT(16);
> + }

The rest looks good, but that should be stored in the sun6i_dma_config
structure too.

Thanks!
Maxime

--
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

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