linux-kernel - Re: [PATCH v1 3/4] dmaengine: imx-sdma: support dmatest

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Message-ID: <20180710153326.GG3219@vkoul-mobl>
Date:   Tue, 10 Jul 2018 21:03:26 +0530
From:   Vinod <vkoul@...nel.org>
To:     Robin Gong <yibin.gong@....com>
Cc:     dan.j.williams@...el.com, shawnguo@...nel.org,
        s.hauer@...gutronix.de, fabio.estevam@....com,
        linux@...linux.org.uk, linux-arm-kernel@...ts.infradead.org,
        kernel@...gutronix.de, dmaengine@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-imx@....com
Subject: Re: [PATCH v1 3/4] dmaengine: imx-sdma: support dmatest

On 11-07-18, 00:23, Robin Gong wrote:
> dmatest(memcpy) will never call dmaengine_slave_config before prep,

and that should have been a hint to you that you should not expect that

> so jobs in dmaengine_slave_config need to be moved into somewhere
> before device_prep_dma_memcpy. Besides, dmatest never setup chan
> ->private as other common case like uart/audio/spi will always setup
> chan->private. Here check it to judge if it's dmatest case and do
> jobs in slave_config.

and you should not do anything for dmatest. Supporting it means memcpy
implementation is not correct :)

> 
> Signed-off-by: Robin Gong <yibin.gong@....com>
> ---
>  drivers/dma/imx-sdma.c | 37 ++++++++++++++++++++++++++++---------
>  1 file changed, 28 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c
> index ed2267d..48f3749 100644
> --- a/drivers/dma/imx-sdma.c
> +++ b/drivers/dma/imx-sdma.c
> @@ -1222,10 +1222,36 @@ static int sdma_alloc_chan_resources(struct dma_chan *chan)
>  {
>  	struct sdma_channel *sdmac = to_sdma_chan(chan);
>  	struct imx_dma_data *data = chan->private;
> +	struct imx_dma_data default_data;
>  	int prio, ret;
>  
> -	if (!data)
> -		return -EINVAL;
> +	ret = clk_enable(sdmac->sdma->clk_ipg);
> +	if (ret)
> +		return ret;
> +	ret = clk_enable(sdmac->sdma->clk_ahb);
> +	if (ret)
> +		goto disable_clk_ipg;
> +	/*
> +	 * dmatest(memcpy) will never call dmaengine_slave_config before prep,
> +	 * so jobs in dmaengine_slave_config need to be moved into somewhere
> +	 * before device_prep_dma_memcpy. Besides, dmatest never setup chan
> +	 * ->private as other common cases like uart/audio/spi will setup
> +	 * chan->private always. Here check it to judge if it's dmatest case
> +	 * and do jobs in slave_config.
> +	 */
> +	if (!data) {
> +		dev_warn(sdmac->sdma->dev, "dmatest is running?\n");

why is that a warning!

> +		sdmac->word_size  =  sdmac->sdma->dma_device.copy_align;
> +		default_data.priority = 2;
> +		default_data.peripheral_type = IMX_DMATYPE_MEMORY;
> +		default_data.dma_request = 0;
> +		default_data.dma_request2 = 0;
> +		data = &default_data;
> +
> +		sdma_config_ownership(sdmac, false, true, false);
> +		sdma_get_pc(sdmac, IMX_DMATYPE_MEMORY);
> +		sdma_load_context(sdmac);
> +	}

this needs to be default for memcpy

-- 
~Vinod