linux-kernel - RE: [PATCH] usb: cdns3: platform_get_irq_byname_optional instead platform_get_irq

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Message-ID: <DM6PR07MB5529095F1B656C5065CBA8B4DD310@DM6PR07MB5529.namprd07.prod.outlook.com>
Date:   Fri, 2 Oct 2020 09:08:35 +0000
From:   Pawel Laszczak <pawell@...ence.com>
To:     Roger Quadros <rogerq@...com>,
        "balbi@...nel.org" <balbi@...nel.org>
CC:     "peter.chen@....org" <peter.chen@....org>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Rahul Kumar <kurahul@...ence.com>
Subject: RE: [PATCH] usb: cdns3: platform_get_irq_byname_optional instead
 platform_get_irq_byname

Roger,

>
>On 30/09/2020 09:57, Pawel Laszczak wrote:
>> To avoid duplicate error information patch replaces platform_get_irq_byname
>> into platform_get_irq_byname_optional.
>
>What is duplicate error information?

The function platform_get_irq_byname print:
" dev_err(&dev->dev, "IRQ %s not found\n", name);" if error occurred. 

In core.c we have the another error message below invoking this function.
e.g 
	if (cdns->dev_irq < 0)
		dev_err(dev, "couldn't get peripheral irq\n");

So, it's looks like one dev_err is  redundant.

>
>>
>> A change was suggested during reviewing CDNSP driver by Chunfeng Yun.
>>
>> Signed-off-by: Pawel Laszczak <pawell@...ence.com>
>> ---
>>   drivers/usb/cdns3/core.c | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/usb/cdns3/core.c b/drivers/usb/cdns3/core.c
>> index a0f73d4711ae..a3f6dc44cf3a 100644
>> --- a/drivers/usb/cdns3/core.c
>> +++ b/drivers/usb/cdns3/core.c
>> @@ -465,7 +465,7 @@ static int cdns3_probe(struct platform_device *pdev)
>>
>>   	cdns->xhci_res[1] = *res;
>>
>> -	cdns->dev_irq = platform_get_irq_byname(pdev, "peripheral");
>> +	cdns->dev_irq = platform_get_irq_byname_optional(pdev, "peripheral");
>
>As per DT binding document, these are mandatory properties

I think that name platform_get_irq_byname_optional is little confusing. 
Function descriptions show that both are almost identical:
/**
 * platform_get_irq_byname_optional - get an optional IRQ for a device by name
 * @dev: platform device
 * @name: IRQ name
 *
 * Get an optional IRQ by name like platform_get_irq_byname(). Except that it
 * does not print an error message if an IRQ can not be obtained.
 *
 * Return: non-zero IRQ number on success, negative error number on failure.
 */

>
>  - interrupts: Interrupts used by cdns3 controller:
>         "host" - interrupt used by XHCI driver.
>         "peripheral" - interrupt used by device driver
>         "otg" - interrupt used by DRD/OTG  part of driver
>
>for dr_mode == "otg" -> all 3 are mandatory.
>for dr_mode == "host" -> "otg" and "peripheral" IRQs are not required.
>for dr_mode == "periphearal" -> "otg" and "host" IRQs are not required.
>
>>   	if (cdns->dev_irq == -EPROBE_DEFER)
>>   		return cdns->dev_irq;
>>
>> @@ -477,7 +477,7 @@ static int cdns3_probe(struct platform_device *pdev)
>>   		return PTR_ERR(regs);
>>   	cdns->dev_regs	= regs;
>>
>> -	cdns->otg_irq = platform_get_irq_byname(pdev, "otg");
>> +	cdns->otg_irq = platform_get_irq_byname_optional(pdev, "otg");
>>   	if (cdns->otg_irq == -EPROBE_DEFER)
>>   		return cdns->otg_irq;
>>
>>
>

Regards,
Pawel