linux-kernel - Re: [PATCH 4.19 070/276] media: stm32-dcmi: return appropriate error codes during probe

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Date:   Fri, 31 May 2019 08:39:18 +0000
From:   Fabien DESSENNE <fabien.dessenne@...com>
To:     Pavel Machek <pavel@...x.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>,
        Hugues FRUCHET <hugues.fruchet@...com>,
        Hans Verkuil <hverkuil-cisco@...all.nl>,
        "Mauro Carvalho Chehab" <mchehab+samsung@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: Re: [PATCH 4.19 070/276] media: stm32-dcmi: return appropriate error
 codes during probe

Hi Pavel


On 31/05/2019 10:19 AM, Pavel Machek wrote:
> Hi!
>
>> [ Upstream commit b5b5a27bee5884860798ffd0f08e611a3942064b ]
>>
>> During probe, return the provided errors value instead of -ENODEV.
>> This allows the driver to be deferred probed if needed.
> This is not correct AFAICT.


The driver gets defer probed *if needed*. *if needed* is for the case 
where platform_get_irq returns -EPROBE_DEFER, which happens if the irq 
controller is not ready yet.

Of course, for the other cases, the probe would just fail.


>
>
>> --- a/drivers/media/platform/stm32/stm32-dcmi.c
>> +++ b/drivers/media/platform/stm32/stm32-dcmi.c
>> @@ -1673,8 +1673,9 @@ static int dcmi_probe(struct platform_device *pdev)
>>   
>>   	irq = platform_get_irq(pdev, 0);
>>   	if (irq <= 0) {
>> -		dev_err(&pdev->dev, "Could not get irq\n");
>> -		return -ENODEV;
>> +		if (irq != -EPROBE_DEFER)
>> +			dev_err(&pdev->dev, "Could not get irq\n");
>> +		return irq;
>>   	}
>>   
>>   	dcmi->res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> irq == 0 is clearly means error here, but will be interpretted as
> success when returned to the caller.


Thank you for pointing this.

It shall be 'return irq ? irq : -ENXIO;'  I will send a fix for this.


>
> As device is not initialized at that point, I'd expect some kind of
> crash later.
> 									Pavel