linux-kernel - Re: [PATCH 6/6] dmaengine: tegra-apb: Disable interrupts on removal

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Message-ID: <5620D7FE.2010205@nvidia.com>
Date:	Fri, 16 Oct 2015 11:57:02 +0100
From:	Jon Hunter <jonathanh@...dia.com>
To:	Lars-Peter Clausen <lars@...afoo.de>,
	Laxman Dewangan <ldewangan@...dia.com>,
	Vinod Koul <vinod.koul@...el.com>,
	Stephen Warren <swarren@...dotorg.org>,
	Thierry Reding <thierry.reding@...il.com>,
	"Alexandre Courbot" <gnurou@...il.com>
CC:	<dmaengine@...r.kernel.org>, <linux-tegra@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 6/6] dmaengine: tegra-apb: Disable interrupts on removal


On 16/10/15 11:40, Lars-Peter Clausen wrote:
> On 10/16/2015 11:29 AM, Jon Hunter wrote:
>>
>> On 16/10/15 09:53, Lars-Peter Clausen wrote:
>>> On 10/16/2015 10:25 AM, Jon Hunter wrote:
>>>> On driver removal, before killing any tasklets, ensure that the channel
>>>> interrupts are disabled so that the tasklet will not try to run during
>>>> or after the removal of the driver.
>>>>
>>>> Signed-off-by: Jon Hunter <jonathanh@...dia.com>
>>>> ---
>>>>  drivers/dma/tegra20-apb-dma.c | 1 +
>>>>  1 file changed, 1 insertion(+)
>>>>
>>>> diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c
>>>> index 2bfab8d28b53..0dd6e7deaa8e 100644
>>>> --- a/drivers/dma/tegra20-apb-dma.c
>>>> +++ b/drivers/dma/tegra20-apb-dma.c
>>>> @@ -1492,6 +1492,7 @@ static int tegra_dma_remove(struct platform_device *pdev)
>>>>  
>>>>  	for (i = 0; i < tdma->chip_data->nr_channels; ++i) {
>>>>  		tdc = &tdma->channels[i];
>>>> +		disable_irq(tdc->irq);
>>>
>>> How about just calling free_irq()? That's how you'd typically handle this.
>>
>> Yes, however, the interrupt is requested by devm_request_irq(). I guess
>> I could call devm_free_irq() here?
> 
> Just use request_irq() instead of devm_request_irq(). You have the same
> issue on the error path in the probe function anyway and also need to add
> the free_irq() before the tasklet_kill() there as well.

I was wondering about that but the tasklets should never be scheduled if
the probe does not succeed, so I think it is ok.

Jon

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