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

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Date:   Tue, 22 Nov 2016 16:57:42 +0100
From:   Maxime Ripard <maxime.ripard@...e-electrons.com>
To:     Hao Zhang <hao5781286@...il.com>
Cc:     wens@...e.org, dan.j.williams@...el.com, vinod.koul@...el.com,
        mark.rutland@....com, robh+dt@...nel.org, catalin.marinas@....com,
        will.deacon@....com, dmaengine@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v4 3/3] dmaengine: sun6i: share the dma driver with sun50i

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@...il.com>
> ---
>  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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