Re: [PATCH 03/11] pinctrl: sunxi: Move setting of mux to irq type from unmask to set_type

[Hans de Goede <hdegoede@redhat.com>]

Hi,

On 05/28/2014 12:33 PM, Maxime Ripard wrote:
> On Wed, May 28, 2014 at 11:51:52AM +0200, Hans de Goede wrote:
>> Hi,
>>
>> On 05/28/2014 11:36 AM, Maxime Ripard wrote:
>>> On Tue, May 27, 2014 at 04:18:29PM +0200, Linus Walleij wrote:
>>>> On Mon, May 26, 2014 at 9:47 AM, Hans de Goede <hdegoede@redhat.com> wrote:
>>>>
>>>>> With level triggered interrupt mask / unmask will get called for each
>>>>> interrupt, doing the somewhat expensive mux setting on each unmask thus is
>>>>> not a good idea. Instead move it to the set_type callback, which is typically
>>>>> done only once for each irq.
>>>>>
>>>>> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
>>>>
>>>> Yes move it out of mask/unmask but no, not into set_type().
>>>>
>>>> Can you not use the irqchip startup()/shutdown() callbacks
>>>> instead?
>>>
>>> I think we can use irq_request_resources then
>>> https://lkml.org/lkml/2014/3/12/307
>>
>> Sounds good, I'll modify the patch to move it here before posting a v2 of
>> this series. Note v2 likely won't happen till this weekend, -ENOTIME.
>>
>>> We could even merge the gpio_to_irq code into it.
>>
>> Erm, no we need that as a separate function for the gpio_chip's to_irq
>> callback.
>
> Linus sent a patch stating otherwise a few weeks ago, and was
> suggesting moving it to irq_startup.
>
> https://lkml.org/lkml/2014/5/9/50

That is not going to work, that patch uses gpiochip_irqchip_add,
which in turn uses gpiochip_to_irq as to_irq handler, which
assumes that gpio offset == irq offset, which is not true for
sunxi-pinctrl.

Specifically gpio_chio_to_irq does:

static int gpiochip_to_irq(struct gpio_chip *chip, unsigned offset)
{
         return irq_find_mapping(chip->irqdomain, offset);
}

Where as the sunxi code does (simplified):

static int sunxi_pinctrl_gpio_to_irq(struct gpio_chip *chip, unsigned offset)
{
	struct sunxi_desc_function *desc = sunxi_pinctrl_desc_find_function_by_pin(pctl, offset, "irq");
	return irq_find_mapping(pctl->domain, desc->irqnum);\
}

Note the extra level of indirection.

Regards,

Hans