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Subject: Re: [PATCH] usb: cdns3: platform_get_irq_byname_optional instead
 platform_get_irq_byname
To:     Pawel Laszczak <pawell@cadence.com>,
        "balbi@kernel.org" <balbi@kernel.org>
CC:     "peter.chen@nxp.org" <peter.chen@nxp.org>,
        "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
        "linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Rahul Kumar <kurahul@cadence.com>
References: <20200930065758.23740-1-pawell@cadence.com>
 <722fa58e-604b-bc34-d404-caf7939bb176@ti.com>
 <DM6PR07MB5529095F1B656C5065CBA8B4DD310@DM6PR07MB5529.namprd07.prod.outlook.com>
From:   Roger Quadros <rogerq@ti.com>
Message-ID: <b73f6bb7-8e5e-d5f9-5adf-f6b10bdb5fb6@ti.com>
Date:   Fri, 2 Oct 2020 13:06:24 +0300
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Pawel,

On 02/10/2020 12:08, Pawel Laszczak wrote:
> 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.

If we want all 3 IRQs to be valid irrespective of dr_mode then we should
use platform_get_irq_byname() and error out in probe if (ret < 0 && ret != -EPROBE_DEFER).

We can get rid of the irq check and duplicate error message in other places.

cheers,
-roger

> 
>>
>>>
>>> A change was suggested during reviewing CDNSP driver by Chunfeng Yun.
>>>
>>> Signed-off-by: Pawel Laszczak <pawell@cadence.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
> 

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