Re: [PATCH v4 3/3] dmaengine: sun6i: share the dma driver with sun50i

From: Maxime Ripard
Date: Tue Nov 22 2016 - 10:58:04 EST


Hi,

On Sun, Nov 20, 2016 at 06:45:40PM +0800, Hao Zhang wrote:
> Changes the limited buswith to 8 bytes,and add
> the test in sun6i_dma_config function
>
> Accroding to sun6i dma driver, i think ,if the client
> doesn't configure the address width with dmaengine_slave_config
> function, it would use the default width. So we can add the test
> in sun6i_dma_config function called by dmaengine_slave_config,
> and test the configuration whether is support for the device.
>
> Signed-off-by: Hao Zhang <hao5781286@xxxxxxxxx>
> ---
> drivers/dma/sun6i-dma.c | 33 ++++++++++++++++++++++++++++++++-
> 1 file changed, 32 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/dma/sun6i-dma.c b/drivers/dma/sun6i-dma.c
> index a235878..f7c90b6 100644
> --- a/drivers/dma/sun6i-dma.c
> +++ b/drivers/dma/sun6i-dma.c
> @@ -250,7 +250,7 @@ static inline s8 convert_burst(u32 maxburst)
> static inline s8 convert_buswidth(enum dma_slave_buswidth addr_width)
> {
> if ((addr_width < DMA_SLAVE_BUSWIDTH_1_BYTE) ||
> - (addr_width > DMA_SLAVE_BUSWIDTH_4_BYTES))
> + (addr_width > DMA_SLAVE_BUSWIDTH_8_BYTES))
> return -EINVAL;
>
> return addr_width >> 1;
> @@ -758,6 +758,18 @@ static int sun6i_dma_config(struct dma_chan *chan,
> {
> struct sun6i_vchan *vchan = to_sun6i_vchan(chan);
>
> + if ((BIT(config->src_addr_width) | chan->device->src_addr_widths) !=
> + chan->device->src_addr_widths) {

Using an and operator would make this more obvious.

> + dev_err(chan2dev(chan), "Invalid DMA configuration\n");
> + return -EINVAL;
> + }
> +
> + if ((BIT(config->dst_addr_width) | chan->device->dst_addr_widths) !=
> + chan->device->dst_addr_widths) {
> + dev_err(chan2dev(chan), "Invalid DMA configuration\n");
> + return -EINVAL;
> + }
> +

And I really think both these tests should be in
dmaengine_slave_config directly. There's nothing special about those
tests, and they apply to all the DMA drivers.

Thanks!
Maxime

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

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