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    SubjectRe: [PATCH v4 05/10] mfd: max77650: new core mfd driver
    śr., 13 lut 2019 o 10:25 Lee Jones <lee.jones@linaro.org> napisał(a):
    >
    > On Tue, 12 Feb 2019, Lee Jones wrote:
    >
    > > On Tue, 12 Feb 2019, Bartosz Golaszewski wrote:
    > >
    > > > wt., 12 lut 2019 o 12:14 Lee Jones <lee.jones@linaro.org> napisał(a):
    > > > >
    > > > > On Tue, 12 Feb 2019, Bartosz Golaszewski wrote:
    > > > >
    > > > > > wt., 12 lut 2019 o 11:18 Lee Jones <lee.jones@linaro.org> napisał(a):
    > > > > > >
    > > > > > > On Tue, 12 Feb 2019, Bartosz Golaszewski wrote:
    > > > > > >
    > > > > > > > wt., 12 lut 2019 o 10:55 Lee Jones <lee.jones@linaro.org> napisał(a):
    > > > > > > > >
    > > > > > > > > * The declaration of a superfluous struct
    > > > > > > > > * 100 lines of additional/avoidable code
    > > > > > > > > * Hacky hoop jumping trying to fudge VIRQs into resources
    > > > > > > > > * Resources were designed for HWIRQs (unless a domain is present)
    > > > > > > > > * Loads of additional/avoidable CPU cycles setting all this up
    > > > > > > >
    > > > > > > > While the above may be right, this one is negligible and you know it. :)
    > > > > > >
    > > > > > > You have nested for() loops. You *are* wasting lots of cycles.
    > > > > > >
    > > > > > > > > Need I go on? :)
    > > > > > > > >
    > > > > > > > > Surely the fact that you are using both sides of an API
    > > > > > > > > (devm_regmap_init_i2c and regmap_irq_get_*) in the same driver, must
    > > > > > > > > set some alarm bells ringing?
    > > > > > > > >
    > > > > > > > > This whole HWIRQ setting, VIRQ getting, resource hacking is a mess.
    > > > > > > > >
    > > > > > > > > And for what? To avoid passing IRQ data to a child driver?
    > > > > > > >
    > > > > > > > What do you propose? Should I go back to the approach in v1 and pass
    > > > > > > > the regmap_irq_chip_data to child drivers?
    > > > > > >
    > > > > > > I'm saying you should remove all of this hackery and pass IRQs as they
    > > > > > > are supposed to be passed (like everyone else does).
    > > > > >
    > > > > > I'm not sure what you mean by "like everyone else does" - different
    > > > > > mfd drivers seem to be doing different things. Is a simple struct
    > > > > > containing virtual irq numbers passed to sub-drivers fine?
    > > > >
    > > > > How do you plan on deriving the VIRQs to place into the struct?
    > > >
    > > > Exampe:
    > > >
    > > > struct max77650_gpio_pdata {
    > > > int gpi_irq;
    > > > };
    > > >
    > > > In MFD driver:
    > > >
    > > > struct max77650_gpio_pdata *gpio_data = devm_kmalloc(dev, sizeof(*gpio_data));
    > > >
    > > > gpio_data->gpi_irq = regmap_irq_get_virq(irqchip_data, GPI_NUM);
    > > >
    > > > gpio_cell.platform_data = gpio_data;
    > > >
    > > > In GPIO driver:
    > > >
    > > > struct max77650_gpio_pdata *gpio_data = pdev->dev.platform_data;
    > > >
    > > > int irq = gpio_data->gpi_irq;
    > >
    > > Definitely not. What you're trying to do is a hack.
    > >
    > > If you're using Regmap to handle your IRQs, then you should use Regmap
    > > in the client to pull them out. Setting them via Regmap, then pulling
    > > them out again in the *same driver*, only to store them in platform
    > > data to be passed to a child device is bonkers.
    > >
    > > *Either* use the MFD provided platform-data helpers *or* pass and
    > > handle them via the Regmap APIs, *not* both.
    >
    > Right, a plan has been formed.
    >
    > Hopefully this works and you can avoid all this dancing around.
    >
    > Firstly, you need to make a small change to:
    >
    > drivers/base/regmap/regmap-irq.c
    >
    > Add the following function:
    >
    > struct irq_domain *regmap_irq_get_domain(struct regmap *map)
    >

    We already do have such function and a lot of mfd drivers actually use it.

    > As you can see, it will return the IRQ Domain for the chip.
    >
    > You can then pass this IRQ domain to mfd_add_devices() and it will do
    > the HWIRQ => VIRQ mapping for you on the fly. Meaning that you can
    > remove all the nastiness in max77650_setup_irqs() and have the Input
    > device use the standard (e.g. platform_get_irq()) APIs.
    >
    > How does that Sound?
    >

    This does sound better! Why didn't you lead with that in the first place?

    It's a pity it's not documented, I had to look at the code to find out
    irq resources would get translated in mfd_add_devices() if a domain is
    present.

    In that case - I really don't see a reason to create a superfluous
    structure to only hold the main regmap - we can very well get it from
    the parent device in sub-drivers as I do now.

    Thanks,
    Bartosz

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