linux-kernel - Re: [PATCH 3/3] amba: Properly handle device probe without IRQ domain

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Message-ID: <ee649111-dc07-d6db-8872-dcb692802236@huawei.com>
Date:   Wed, 25 Aug 2021 12:05:13 +0800
From:   Kefeng Wang <wangkefeng.wang@...wei.com>
To:     Saravana Kannan <saravanak@...gle.com>,
        Rob Herring <robh+dt@...nel.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Frank Rowand" <frowand.list@...il.com>,
        <devicetree@...r.kernel.org>, Russell King <linux@...linux.org.uk>,
        Linus Walleij <linus.walleij@...aro.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Ruizhe Lin <linruizhe@...wei.com>, <wangkefeng.wang@...wei.com>
Subject: Re: [PATCH 3/3] amba: Properly handle device probe without IRQ domain


On 2021/8/25 4:08, Saravana Kannan wrote:
> On Tue, Aug 24, 2021 at 1:05 PM Rob Herring <robh+dt@...nel.org> wrote:
>> +Saravana
>>
>> Saravana mentioned to me there may be some issues with this one...
>>
>>
>> On Mon, Aug 16, 2021 at 2:43 AM Kefeng Wang <wangkefeng.wang@...wei.com> wrote:
>>> of_amba_device_create() uses irq_of_parse_and_map() to translate
>>> a DT interrupt specification into a Linux virtual interrupt number.
>>>
>>> But it doesn't properly handle the case where the interrupt controller
>>> is not yet available, eg, when pl011 interrupt is connected to MBIGEN
>>> interrupt controller, because the mbigen initialization is too late,
>>> which will lead to no IRQ due to no IRQ domain found, log is shown below,
>>>    "irq: no irq domain found for uart0 !"
>>>
>>> use of_irq_get() to return -EPROBE_DEFER as above, and in the function
>>> amba_device_try_add()/amba_device_add(), it will properly handle in such
>>> case, also return 0 in other fail cases to be consistent as before.
>>>
>>> Cc: Russell King <linux@...linux.org.uk>
>>> Cc: Rob Herring <robh+dt@...nel.org>
>>> Cc: Frank Rowand <frowand.list@...il.com>
>>> Reported-by: Ruizhe Lin <linruizhe@...wei.com>
>>> Signed-off-by: Kefeng Wang <wangkefeng.wang@...wei.com>
>>> ---
>>>   drivers/amba/bus.c    | 27 +++++++++++++++++++++++++++
>>>   drivers/of/platform.c |  6 +-----
>>>   2 files changed, 28 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
>>> index 36f2f42c8014..720aa6cdd402 100644
>>> --- a/drivers/amba/bus.c
>>> +++ b/drivers/amba/bus.c
>>> @@ -19,6 +19,7 @@
>>>   #include <linux/clk/clk-conf.h>
>>>   #include <linux/platform_device.h>
>>>   #include <linux/reset.h>
>>> +#include <linux/of_irq.h>
>>>
>>>   #include <asm/irq.h>
>>>
>>> @@ -371,12 +372,38 @@ static void amba_device_release(struct device *dev)
>>>          kfree(d);
>>>   }
>>>
>>> +static int of_amba_device_decode_irq(struct amba_device *dev)
>>> +{
>>> +       struct device_node *node = dev->dev.of_node;
>>> +       int i, irq = 0;
>>> +
>>> +       if (IS_ENABLED(CONFIG_OF_IRQ) && node) {
>>> +               /* Decode the IRQs and address ranges */
>>> +               for (i = 0; i < AMBA_NR_IRQS; i++) {
>>> +                       irq = of_irq_get(node, i);
>>> +                       if (irq < 0) {
>>> +                               if (irq == -EPROBE_DEFER)
>>> +                                       return irq;
>>> +                               irq = 0;
>>> +                       }
>>> +
>>> +                       dev->irq[i] = irq;
>>> +               }
>>> +       }
>>> +
>>> +       return 0;
>>> +}
>>> +
>>>   static int amba_device_try_add(struct amba_device *dev, struct resource *parent)
>>>   {
>>>          u32 size;
>>>          void __iomem *tmp;
>>>          int i, ret;
>>>
>>> +       ret = of_amba_device_decode_irq(dev);
>>> +       if (ret)
>>> +               goto err_out;
>>> +
> Similar to other resources the AMBA bus "gets" for the device, I think
> this should be moved into amba_probe() and not here. There's no reason
> to delay the addition of the device (and loading its module) because
> the IRQ isn't ready yet.

The following code in the amba_device_try_add() will be called, it uses irq[0]
and irq[1], so I put of_amba_device_decode_irq() into amba_device_try_add().

470         if (dev->irq[0])
471                 ret = device_create_file(&dev->dev, &dev_attr_irq0);
472         if (ret == 0 && dev->irq[1])
473                 ret = device_create_file(&dev->dev, &dev_attr_irq1);
474         if (ret == 0)
475                 return ret;

of_amba_device_decode_irq() in amba_device_try_add() won't lead to issue,
only delay the device add, right?

If make it into amba_probe(), the above code should be moved too, could we
make a new patch to move both of them, or don't move them?