linux-kernel - Re: [PATCH 1/3] i2c: bcm2835: Use platform_get

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Date:   Sun, 19 Dec 2021 10:21:32 -0800
From:   Florian Fainelli <f.fainelli@...il.com>
To:     "Lad, Prabhakar" <prabhakar.csengg@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>
Cc:     Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>,
        Rob Herring <robh+dt@...nel.org>,
        Nicolas Saenz Julienne <nsaenz@...nel.org>,
        Ray Jui <rjui@...adcom.com>,
        Scott Branden <sbranden@...adcom.com>,
        bcm-kernel-feedback-list@...adcom.com,
        Chris Brandt <chris.brandt@...esas.com>,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        Linux I2C <linux-i2c@...r.kernel.org>,
        linux-rpi-kernel@...ts.infradead.org,
        LAK <linux-arm-kernel@...ts.infradead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>
Subject: Re: [PATCH 1/3] i2c: bcm2835: Use platform_get_irq() to get the
 interrupt



On 12/19/2021 1:52 AM, Lad, Prabhakar wrote:
> Hi Florian,
> 
> On Sat, Dec 18, 2021 at 10:44 PM Lad, Prabhakar
> <prabhakar.csengg@...il.com> wrote:
>>
>> Hi Florian,
>>
>> Thank you for the review.
>>
>> On Sat, Dec 18, 2021 at 9:17 PM Florian Fainelli <f.fainelli@...il.com> wrote:
>>>
>>>
>>>
>>> On 12/18/2021 8:52 AM, Lad Prabhakar wrote:
>>>> platform_get_resource(pdev, IORESOURCE_IRQ, ..) relies on static
>>>> allocation of IRQ resources in DT core code, this causes an issue
>>>> when using hierarchical interrupt domains using "interrupts" property
>>>> in the node as this bypasses the hierarchical setup and messes up the
>>>> irq chaining.
>>>>
>>>> In preparation for removal of static setup of IRQ resource from DT core
>>>> code use platform_get_irq().
>>>>
>>>> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
>>>
>>> Just one nit below:
>>>> ---
>>>>    drivers/i2c/busses/i2c-bcm2835.c | 11 ++++-------
>>>>    1 file changed, 4 insertions(+), 7 deletions(-)
>>>>
>>>> diff --git a/drivers/i2c/busses/i2c-bcm2835.c b/drivers/i2c/busses/i2c-bcm2835.c
>>>> index 37443edbf754..d63dec5f3cb1 100644
>>>> --- a/drivers/i2c/busses/i2c-bcm2835.c
>>>> +++ b/drivers/i2c/busses/i2c-bcm2835.c
>>>> @@ -402,7 +402,7 @@ static const struct i2c_adapter_quirks bcm2835_i2c_quirks = {
>>>>    static int bcm2835_i2c_probe(struct platform_device *pdev)
>>>>    {
>>>>        struct bcm2835_i2c_dev *i2c_dev;
>>>> -     struct resource *mem, *irq;
>>>> +     struct resource *mem;
>>>>        int ret;
>>>>        struct i2c_adapter *adap;
>>>>        struct clk *mclk;
>>>> @@ -452,12 +452,9 @@ static int bcm2835_i2c_probe(struct platform_device *pdev)
>>>>                return ret;
>>>>        }
>>>>
>>>> -     irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
>>>> -     if (!irq) {
>>>> -             dev_err(&pdev->dev, "No IRQ resource\n");
>>>> -             return -ENODEV;
>>>> -     }
>>>> -     i2c_dev->irq = irq->start;
>>>> +     i2c_dev->irq = platform_get_irq(pdev, 0);
>>>> +     if (i2c_dev->irq <= 0)
>>>> +             return i2c_dev->irq ? i2c_dev->irq : -ENXIO;
>>>
>>> Why not just check for a negative return code and propagate it as is?
>>>
>> platform_get_irq() may return 0 said that we do get a splat in this
>> case and further request_irq() will fail so instead check it here.
>>
> My bad, just the negative check should suffice.

Think so too, looking forward to v2, thanks!
-- 
Florian