linux-kernel - Re: [PATCH v4 2/4] dmaengine: Add STM32 MDMA driver

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Date:   Thu, 28 Sep 2017 15:17:49 +0200
From:   Pierre Yves MORDRET <pierre-yves.mordret@...com>
To:     Vinod Koul <vinod.koul@...el.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 v4 2/4] dmaengine: Add STM32 MDMA driver



On 09/28/2017 10:13 AM, Vinod Koul wrote:
> On Fri, Aug 25, 2017 at 04:31:04PM +0200, Pierre-Yves MORDRET wrote:
>> +static int stm32_mdma_probe(struct platform_device *pdev)
>> +{
> 
> [snip]
> 
>> +	dmadev = devm_kzalloc(&pdev->dev, sizeof(*dmadev) + sizeof(u32) * count,
>> +			      GFP_KERNEL);
>> +	if (!dmadev)
>> +		return -ENOMEM;
>> +
>> +	dmadev->nr_channels = nr_channels;
>> +	dmadev->nr_requests = nr_requests;
>> +	device_property_read_u32_array(&pdev->dev, "st,ahb-addr-masks",
>> +				       dmadev->ahb_addr_masks,
>> +				       count);
>> +	dmadev->nr_ahb_addr_masks = count;
>> +
>> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +	dmadev->base = devm_ioremap_resource(&pdev->dev, res);
>> +	if (IS_ERR(dmadev->base))
>> +		return PTR_ERR(dmadev->base);
>> +
>> +	dmadev->clk = devm_clk_get(&pdev->dev, NULL);
>> +	if (IS_ERR(dmadev->clk)) {
>> +		dev_err(&pdev->dev, "Error: Missing controller clock\n");
>> +		return PTR_ERR(dmadev->clk);
>> +	}
> 
> I am assuming if clk is not availble at this point of time you return clk
> error which maybe defer probe, right?

Yes. So I will add an "if" statement as I did for DMAMUX
if (ret == -EPROBE_DEFER)
   dev_info .... (instead of dev_err)

> 
>> +static struct platform_driver stm32_mdma_driver = {
>> +	.driver = {
>> +		.name = "stm32-mdma",
>> +		.of_match_table = stm32_mdma_of_match,
>> +	},
>> +};
>> +
>> +static int __init stm32_mdma_init(void)
>> +{
>> +	return platform_driver_probe(&stm32_mdma_driver, stm32_mdma_probe);
> 
> and you register platform_driver_probe() which per
> drivers/base/platform.c:760 is incompatible with defer probing.
> So this need a fix
> 

Will change to platform_driver_register

Thanks and regards