linux-kernel - Re: [PATCH v2 01/13] iommu/rockchip: Request irqs in rk_iommu

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Date:   Wed, 17 Jan 2018 16:16:49 +0900
From:   Tomasz Figa <tfiga@...omium.org>
To:     JeffyChen <jeffy.chen@...k-chips.com>
Cc:     linux-kernel@...r.kernel.org, Ricky Liang <jcliang@...omium.org>,
        Robin Murphy <robin.murphy@....com>,
        simon xue <xxm@...k-chips.com>,
        Heiko Stuebner <heiko@...ech.de>,
        "open list:ARM/Rockchip SoC..." <linux-rockchip@...ts.infradead.org>,
        open@....net,
        "list@....net:IOMMU DRIVERS <iommu@...ts.linux-foundation.org>, Joerg
        Roedel <joro@...tes.org>," <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v2 01/13] iommu/rockchip: Request irqs in rk_iommu_probe()

On Wed, Jan 17, 2018 at 4:08 PM, JeffyChen <jeffy.chen@...k-chips.com> wrote:
> Hi Tomasz,
>
> Thanks for your reply.
>
> On 01/17/2018 12:21 PM, Tomasz Figa wrote:
>>
>> Hi Jeffy,
>>
>> Thanks for the patch. Please see my comments inline.
>>
>> On Tue, Jan 16, 2018 at 10:25 PM, Jeffy Chen <jeffy.chen@...k-chips.com>
>> wrote:
>>
>> Please add patch description.
>
>
> ok, will do.
>>
>>
>>> Suggested-by: Robin Murphy <robin.murphy@....com>
>>> Signed-off-by: Jeffy Chen <jeffy.chen@...k-chips.com>
>>> ---
>>
>> [snip]
>>>
>>> -       for (i = 0; i < iommu->num_irq; i++) {
>>> -               iommu->irq[i] = platform_get_irq(pdev, i);
>>> -               if (iommu->irq[i] < 0) {
>>> -                       dev_err(dev, "Failed to get IRQ, %d\n",
>>> iommu->irq[i]);
>>> +       num_irq = of_irq_count(dev->of_node);
>>> +       for (i = 0; i < num_irq; i++) {
>>> +               irq = platform_get_irq(pdev, i);
>>
>>
>> This lacks consistency. of_irq_count() is used for counting, but
>> platform_get_irq() is used for getting. Either platform_ or of_ API
>> should be used for both and I'd lean for platform_, since it's more
>> general.
>
> hmmm, right, i was thinking of removing num_irq, and do something like:
> while (nr++) {
>   err = platform_get_irq(dev, nr);
>   if (err == -EPROBE_DEFER)
>      break;
>   if (err < 0)
>      return err;
>   ....
> }
>
> but forgot to do that..

Was there anything wrong with platform_irq_count() used by existing code?

>
>>
>>> +               if (irq < 0) {
>>> +                       dev_err(dev, "Failed to get IRQ, %d\n", irq);
>>>                          return -ENXIO;
>>>                  }
>>> +               err = devm_request_irq(iommu->dev, irq, rk_iommu_irq,
>>> +                                      IRQF_SHARED, dev_name(dev),
>>> iommu);
>>> +               if (err)
>>> +                       return err;
>>>          }
>>
>>
>> Looks like there is some more initialization below. Is the driver okay
>> with the IRQ being potentially fired right here? (Shared IRQ handlers
>> might be run at request_irq() time for testing.)
>>
> right, forget about that. maybe we can check iommu->domain not NULL in
> rk_iommu_irq()

Maybe we could just move IRQ requesting to the end of probe?

Best regards,
Tomasz