linux-kernel - Re: [PATCH v3 2/5] dmaengine: Add STM32 DMAMUX driver

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Message-ID: <20170722065133.GT3053@localhost>
Date:   Sat, 22 Jul 2017 12:21:33 +0530
From:   Vinod Koul <vinod.koul@...el.com>
To:     Pierre-Yves MORDRET <pierre-yves.mordret@...com>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        Russell King <linux@...linux.org.uk>,
        Dan Williams <dan.j.williams@...el.com>,
        M'boumba Cedric Madianga <cedric.madianga@...il.com>,
        Fabrice GASNIER <fabrice.gasnier@...com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Fabien DESSENNE <fabien.dessenne@...com>,
        Amelie Delaunay <amelie.delaunay@...com>,
        dmaengine@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 2/5] dmaengine: Add STM32 DMAMUX driver

On Thu, Jul 06, 2017 at 02:20:20PM +0200, Pierre-Yves MORDRET wrote:
> +static int stm32_dmamux_probe(struct platform_device *pdev)
> +{
> +	struct device_node *node = pdev->dev.of_node;
> +	struct device_node *dma_node;
> +	struct stm32_dmamux_data *stm32_dmamux;
> +	struct resource *res;
> +	void __iomem *iomem;
> +	int i, ret;
> +
> +	if (!node)
> +		return -ENODEV;
> +
> +	stm32_dmamux = devm_kzalloc(&pdev->dev, sizeof(*stm32_dmamux),
> +				    GFP_KERNEL);
> +	if (!stm32_dmamux)
> +		return -ENOMEM;
> +
> +	dma_node = of_parse_phandle(node, "dma-masters", 0);
> +	if (!dma_node) {
> +		dev_err(&pdev->dev, "Can't get DMA master node\n");
> +		return -ENODEV;
> +	}
> +
> +	if (device_property_read_u32(&pdev->dev, "dma-channels",
> +				     &stm32_dmamux->dmamux_channels))
> +		stm32_dmamux->dmamux_channels = STM32_DMAMUX_MAX_CHANNELS;
> +
> +	if (device_property_read_u32(&pdev->dev, "dma-requests",
> +				     &stm32_dmamux->dmamux_requests))
> +		stm32_dmamux->dmamux_requests = STM32_DMAMUX_MAX_REQUESTS;

I think defaults should be warned here too

> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!res)
> +		return -ENODEV;
> +
> +	iomem = devm_ioremap_resource(&pdev->dev, res);
> +	if (!iomem)
> +		return -ENOMEM;
> +
> +	spin_lock_init(&stm32_dmamux->lock);
> +
> +	stm32_dmamux->clk = devm_clk_get(&pdev->dev, NULL);
> +	if (IS_ERR(stm32_dmamux->clk)) {
> +		dev_info(&pdev->dev, "Missing controller clock\n");

Can you check for EPROBE_DEFER and print only for if that is not the error
otherwise we end up sapmming with defered probe issues

> +
> +#ifndef __DMA_STM32_DMAMUX_H
> +#define __DMA_STM32_DMAMUX_H
> +
> +#if defined(CONFIG_STM32_DMAMUX)
> +int stm32_dmamux_set_config(struct device *dev, void *route_data, u32 chan_id);

Why do we need a custom API in this case?

-- 
~Vinod