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Subject: Re: [PATCH v1] usb: xhci: tegra: Check padctrl interrupt presence in
 device tree
To:     =?UTF-8?B?TWljaGHFgiBNaXJvc8WCYXc=?= <mirq-linux@rere.qmqm.pl>
Cc:     Thierry Reding <treding@nvidia.com>,
        Jonathan Hunter <jonathanh@nvidia.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Mathias Nyman <mathias.nyman@intel.com>,
        JC Kuo <jckuo@nvidia.com>, Nicolas Chauvet <kwizart@gmail.com>,
        linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-tegra@vger.kernel.org
References: <20211021115501.14932-1-digetx@gmail.com>
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From:   Dmitry Osipenko <digetx@gmail.com>
Message-ID: <0a48c38e-1841-0dc9-473e-5dbe67ce04d5@gmail.com>
Date:   Fri, 22 Oct 2021 08:58:02 +0300
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22.10.2021 01:14, Michał Mirosław пишет:
> On Fri, Oct 22, 2021 at 12:46:23AM +0300, Dmitry Osipenko wrote:
>> 22.10.2021 00:37, Michał Mirosław пишет:
>>> On Thu, Oct 21, 2021 at 02:55:01PM +0300, Dmitry Osipenko wrote:
>>>> Older device-trees don't specify padctrl interrupt and xhci-tegra driver
>>>> now fails to probe with -EINVAL using those device-trees. Check interrupt
>>>> presence and disallow runtime PM suspension if it's missing to fix the
>>>> trouble.
>>> [...]
>>>> --- a/drivers/usb/host/xhci-tegra.c
>>>> +++ b/drivers/usb/host/xhci-tegra.c
>>>> @@ -1454,10 +1454,13 @@ static int tegra_xusb_probe(struct platform_device *pdev)
>>>>  		goto put_padctl;
>>>>  	}
>>>>  
>>>> -	tegra->padctl_irq = of_irq_get(np, 0);
>>>> -	if (tegra->padctl_irq <= 0) {
>>>> -		err = (tegra->padctl_irq == 0) ? -ENODEV : tegra->padctl_irq;
>>>> -		goto put_padctl;
>>>> +	/* Older device-trees don't specify padctrl interrupt */
>>>> +	if (of_property_read_bool(np, "interrupts")) {
>>>
>>> Does this catch "interrupts-extended"?
>>
>> No, Tegra doesn't use interrupts-extended.
> 
> I believe it is generic and equivalent to "interrupt-parent" +
> "interrupts" properties, so people might as well put this in
> the DT to save (or loose) a few bytes.
> 
> You could just check if of_irq_get() returned -EINVAL instead of
> matching "interrupts" property.

It should be a bad idea to rely on -EINVAL since it's ambiguous error code.

Perhaps it's fine to assume that today of_irq_get() may only return
-EINVAL in a case of a missing DT property, but then it should be two
patches here:

1. Use -EINVAL and backport this fix to stable kernel.
2. Change of_irq_get() to return -ENOENT for a missing property and
change tegra_xusb_probe() accordingly.