linux-kernel - Re: [PATCH v2] dmaengine: axi-dmac: Request IRQ with IRQF

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Date:   Fri, 27 Apr 2018 08:53:39 +0200
From:   Lars-Peter Clausen <lars@...afoo.de>
To:     Vinod Koul <vinod.koul@...el.com>, Moritz Fischer <mdf@...nel.org>
Cc:     linux-kernel@...r.kernel.org, dmaengine@...r.kernel.org,
        dan.j.williams@...el.com
Subject: Re: [PATCH v2] dmaengine: axi-dmac: Request IRQ with IRQF_SHARED

On 04/27/2018 07:11 AM, Vinod Koul wrote:
> On Thu, Apr 26, 2018 at 10:40:00AM -0700, Moritz Fischer wrote:
>> Request IRQ with IRQF_SHARED flag. This works since the interrupt
>> handler already checks if there is an actual IRQ pending and returns
>> IRQ_NONE otherwise.
> 
> hmmm what are we trying to fix here? Is your device on a shared line or not?

IRQF_SHARED does not mean that the IRQ is on a shared line. It means that
the driver can handle it if the IRQ is on a shared line. Since the driver
can handle it setting the flag is a good idea since this enables usecases
where the line is shared.

> 
>>
>> Acked-by: Lars-Peter Clausen <lars@...afoo.de>
>> Signed-off-by: Moritz Fischer <mdf@...nel.org>
>> ---
>> Changes from v1:
>> - Added Lars' Acked-by
>> - Dropped patch [1/2] and changed accordingly
>> ---
>>  drivers/dma/dma-axi-dmac.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/dma/dma-axi-dmac.c b/drivers/dma/dma-axi-dmac.c
>> index 2419fe524daa..15b2453d2647 100644
>> --- a/drivers/dma/dma-axi-dmac.c
>> +++ b/drivers/dma/dma-axi-dmac.c
>> @@ -687,7 +687,7 @@ static int axi_dmac_probe(struct platform_device *pdev)
>>  	if (ret)
>>  		goto err_unregister_device;
>>  
>> -	ret = request_irq(dmac->irq, axi_dmac_interrupt_handler, 0,
>> +	ret = request_irq(dmac->irq, axi_dmac_interrupt_handler, IRQF_SHARED,
>>  		dev_name(&pdev->dev), dmac);
>>  	if (ret)
>>  		goto err_unregister_of;
>> -- 
>> 2.17.0
>>
>