Re: [PATCH RFC 1/2] dt-bindings: pinctl: amlogic,pinctrl-a4: Add gpio irq property

[Xianwei Zhao <xianwei.zhao@amlogic.com>]

Hi Krzysztof,
    Thanks for your detailed review. After considering the feedback, I 
think this approach is not suitable, so I will drop this patch.

On 2026/6/15 13:32, Krzysztof Kozlowski wrote:
> On 15/06/2026 04:47, Xianwei Zhao wrote:
>> Hi Conor,
>>      Thanks for your review.
>>
>> On 2026/6/12 01:39, Conor Dooley wrote:
>>> Subject:
>>> Re: [PATCH RFC 1/2] dt-bindings: pinctl: amlogic,pinctrl-a4: Add gpio
>>> irq property
>>> From:
>>> Conor Dooley<conor@kernel.org>
>>> Date:
>>> 2026/6/12 01:39
>>>
>>> To:
>>> xianwei.zhao@amlogic.com
>>> CC:
>>> Linus Walleij<linusw@kernel.org>, Rob Herring<robh@kernel.org>,
>>> Krzysztof Kozlowski<krzk+dt@kernel.org>, Conor Dooley
>>> <conor+dt@kernel.org>, Neil Armstrong<neil.armstrong@linaro.org>, Kevin
>>> Hilman<khilman@baylibre.com>, Jerome Brunet<jbrunet@baylibre.com>,
>>> Martin Blumenstingl<martin.blumenstingl@googlemail.com>,
>>> linux-amlogic@lists.infradead.org,linux-gpio@vger.kernel.org,
>>> devicetree@vger.kernel.org,linux-kernel@vger.kernel.org,
>>> linux-arm-kernel@lists.infradead.org
>>>
>>>
>>>
>>> On Thu, Jun 11, 2026 at 07:54:33AM +0000, Xianwei Zhao via B4 Relay wrote:
>>>> From: Xianwei Zhao<xianwei.zhao@amlogic.com>
>>>>
>>>> Add the hw-irq property for each GPIO bank and enable interrupt-parent
>>>> for pinctrl so that gpiod_to_irq() can translate GPIO lines to IRQs.
>>> Uhhhhh, what? Why can't you just use the normal interrupts property?
>>>
>> The interrupt cannot be used directly because the GPIO bank only
>> provides an IRQ base, which does not have a one-to-one mapping with the
>> actual hardware interrupts.
>>
>> On Amlogic SoCs, GPIO interrupts are handled through a mux. Multiple
>> GPIO pins are mapped to a limited number of real interrupt sources. The
>> implementation can be found here:
>>
>> https://github.com/torvalds/linux/blob/master/drivers/irqchip/irq-meson-gpio.c
>>
>> To use a GPIO interrupt, an unused hardware interrupt must first be
>> allocated, and then the corresponding mux register must be configured.
>> This allocation and mapping are already implemented in the existing driver.
>>
>> In that driver, the mapping is performed dynamically rather than simply
>> calculating:
>>
>> irq = irq_start + gpio_offset
>>
>> If the interrupt is used directly, only the GPIO index can be obtained.
> 
> If it is performed dynamically, then it is not suitable for DT.
> 
> You still did not explain what hardware aspect exactly is described by
> "hw-irq".
> 
> 
> 
>> The real interrupt number cannot be derived by simply adding an offset,
>> because the hardware interrupt must be allocated first. Pre-allocating
>> all interrupts during initialization would prevent later GPIOs from
>> obtaining available interrupt sources.
>>
>> Perhaps other names would be more appropriate here, such as "irq_start".
>>
>>>> Signed-off-by: Xianwei Zhao<xianwei.zhao@amlogic.com>
>>>> ---
> Best regards,
> Krzysztof