| Message ID | 20201117213351.249668-1-linus.walleij@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | [1/2,v1] gpio: sifive: Set affinity callback to parent | expand |
Hi Linus, On Tue, Nov 17, 2020 at 10:37 PM Linus Walleij <linus.walleij@linaro.org> wrote: > This assigns the .irq_set_affinity to the parent callback. > I assume the sifive GPIO can be used in systems with > SMP. > > I used the pattern making the hirerarchy tolerant for missing > parent as in Marc's earlier patches. > > Cc: Yash Shah <yash.shah@sifive.com> > Cc: Wesley W. Terpstra <wesley@sifive.com> > Suggested-by: Marc Zyngier <maz@kernel.org> > Signed-off-by: Linus Walleij <linus.walleij@linaro.org> Thanks for your patch! > --- > ChangeLog RFT->v1: > - Make the affinity setting call return -EINVAL if there > is no parent. Would it make sense to incorporate this check into irq_chip_set_affinity_parent(), so drivers can just point .irq_set_affinity to the latter, without having to provide (duplicate) the same wrapper over and over? > - Real patch because now we believe in this > --- > drivers/gpio/gpio-sifive.c | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/drivers/gpio/gpio-sifive.c b/drivers/gpio/gpio-sifive.c > index c54dd08f2cbf..485820e4488c 100644 > --- a/drivers/gpio/gpio-sifive.c > +++ b/drivers/gpio/gpio-sifive.c > @@ -128,6 +128,16 @@ static void sifive_gpio_irq_eoi(struct irq_data *d) > irq_chip_eoi_parent(d); > } > > +static int sifive_gpio_irq_set_affinity(struct irq_data *data, > + const struct cpumask *dest, > + bool force) > +{ > + if (data->parent_data) > + return irq_chip_set_affinity_parent(data, dest, force); > + > + return -EINVAL; > +} > + > static struct irq_chip sifive_gpio_irqchip = { > .name = "sifive-gpio", > .irq_set_type = sifive_gpio_irq_set_type, > @@ -136,6 +146,7 @@ static struct irq_chip sifive_gpio_irqchip = { > .irq_enable = sifive_gpio_irq_enable, > .irq_disable = sifive_gpio_irq_disable, > .irq_eoi = sifive_gpio_irq_eoi, > + .irq_set_affinity = sifive_gpio_irq_set_affinity, > }; Gr{oetje,eeting}s, Geert
On Tue, 06 Apr 2021 11:20:57 +0100, Geert Uytterhoeven <geert@linux-m68k.org> wrote: > > Hi Linus, > > On Tue, Nov 17, 2020 at 10:37 PM Linus Walleij <linus.walleij@linaro.org> wrote: > > This assigns the .irq_set_affinity to the parent callback. > > I assume the sifive GPIO can be used in systems with > > SMP. > > > > I used the pattern making the hirerarchy tolerant for missing > > parent as in Marc's earlier patches. > > > > Cc: Yash Shah <yash.shah@sifive.com> > > Cc: Wesley W. Terpstra <wesley@sifive.com> > > Suggested-by: Marc Zyngier <maz@kernel.org> > > Signed-off-by: Linus Walleij <linus.walleij@linaro.org> > > Thanks for your patch! > > > --- > > ChangeLog RFT->v1: > > - Make the affinity setting call return -EINVAL if there > > is no parent. > > Would it make sense to incorporate this check into > irq_chip_set_affinity_parent(), so drivers can just point > .irq_set_affinity to the latter, without having to provide (duplicate) > the same wrapper over and over? Calling one of the irq_chip_*_parent() functions assumes that there *is* a parent at all times, because you really need to know what context you are in by construction. There are a couple of exceptions to this rule (irqchip state, retriggering), but overall I'd like to stick to it and leave the checks on the implementations that have weird setups. I would assume that it is possible to know at the point where you map the interrupt whether it has a parent or not, and use a different irqchip. Is that doable in this case? Thanks, M.
Hi Marc, On Tue, Apr 6, 2021 at 12:40 PM Marc Zyngier <maz@kernel.org> wrote: > On Tue, 06 Apr 2021 11:20:57 +0100, > Geert Uytterhoeven <geert@linux-m68k.org> wrote: > > On Tue, Nov 17, 2020 at 10:37 PM Linus Walleij <linus.walleij@linaro.org> wrote: > > > This assigns the .irq_set_affinity to the parent callback. > > > I assume the sifive GPIO can be used in systems with > > > SMP. > > > > > > I used the pattern making the hirerarchy tolerant for missing > > > parent as in Marc's earlier patches. > > > > > > Cc: Yash Shah <yash.shah@sifive.com> > > > Cc: Wesley W. Terpstra <wesley@sifive.com> > > > Suggested-by: Marc Zyngier <maz@kernel.org> > > > Signed-off-by: Linus Walleij <linus.walleij@linaro.org> > > > > Thanks for your patch! > > > > > --- > > > ChangeLog RFT->v1: > > > - Make the affinity setting call return -EINVAL if there > > > is no parent. > > > > Would it make sense to incorporate this check into > > irq_chip_set_affinity_parent(), so drivers can just point > > .irq_set_affinity to the latter, without having to provide (duplicate) > > the same wrapper over and over? > > Calling one of the irq_chip_*_parent() functions assumes that there > *is* a parent at all times, because you really need to know what > context you are in by construction. There are a couple of exceptions > to this rule (irqchip state, retriggering), but overall I'd like to > stick to it and leave the checks on the implementations that have > weird setups. > > I would assume that it is possible to know at the point where you map > the interrupt whether it has a parent or not, and use a different > irqchip. Is that doable in this case? I think you're missing my point (or I'm missing yours ;-) I don't mean to set up .irq_set_affinity = irq_chip_set_affinity_parent() by default. Right now, several drivers do this: static int foo_irq_set_affinity(struct irq_data *data, const struct cpumask *dest, bool force) { if (data->parent_data) return irq_chip_set_affinity_parent(data, dest, force); return -EINVAL; } .irq_set_affinity = foo_irq_set_affinity, If irq_chip_set_affinity_parent() would not blindly dereference data->parent_data, there would be no need for the foo_irq_set_affinity() wrappers. Or are all those drivers using such a wrapper wrong? Thanks! Gr{oetje,eeting}s, Geert
Hi Geert, On Tue, 06 Apr 2021 11:51:25 +0100, Geert Uytterhoeven <geert@linux-m68k.org> wrote: > > Hi Marc, > > On Tue, Apr 6, 2021 at 12:40 PM Marc Zyngier <maz@kernel.org> wrote: > > On Tue, 06 Apr 2021 11:20:57 +0100, > > Geert Uytterhoeven <geert@linux-m68k.org> wrote: > > > On Tue, Nov 17, 2020 at 10:37 PM Linus Walleij <linus.walleij@linaro.org> wrote: > > > > This assigns the .irq_set_affinity to the parent callback. > > > > I assume the sifive GPIO can be used in systems with > > > > SMP. > > > > > > > > I used the pattern making the hirerarchy tolerant for missing > > > > parent as in Marc's earlier patches. > > > > > > > > Cc: Yash Shah <yash.shah@sifive.com> > > > > Cc: Wesley W. Terpstra <wesley@sifive.com> > > > > Suggested-by: Marc Zyngier <maz@kernel.org> > > > > Signed-off-by: Linus Walleij <linus.walleij@linaro.org> > > > > > > Thanks for your patch! > > > > > > > --- > > > > ChangeLog RFT->v1: > > > > - Make the affinity setting call return -EINVAL if there > > > > is no parent. > > > > > > Would it make sense to incorporate this check into > > > irq_chip_set_affinity_parent(), so drivers can just point > > > .irq_set_affinity to the latter, without having to provide (duplicate) > > > the same wrapper over and over? > > > > Calling one of the irq_chip_*_parent() functions assumes that there > > *is* a parent at all times, because you really need to know what > > context you are in by construction. There are a couple of exceptions > > to this rule (irqchip state, retriggering), but overall I'd like to > > stick to it and leave the checks on the implementations that have > > weird setups. > > > > I would assume that it is possible to know at the point where you map > > the interrupt whether it has a parent or not, and use a different > > irqchip. Is that doable in this case? > > I think you're missing my point (or I'm missing yours ;-) > > I don't mean to set up .irq_set_affinity = irq_chip_set_affinity_parent() > by default. > > Right now, several drivers do this: > > static int foo_irq_set_affinity(struct irq_data *data, > const struct cpumask *dest, > bool force) > { > if (data->parent_data) > return irq_chip_set_affinity_parent(data, dest, force); > > return -EINVAL; > } > > .irq_set_affinity = foo_irq_set_affinity, > > If irq_chip_set_affinity_parent() would not blindly dereference > data->parent_data, there would be no need for the > foo_irq_set_affinity() wrappers. The "blind dereference" is a completely assumed design choice. That's because when you instantiate an irqchip, you know whether there is another chip on the IRQ path, or whether this is a root (or a mux, which amounts to the same thing). So in most cases, you shouldn't need to check for a parent. You know there is one by construction, and if there isn't one, you don't call the *_parent() anyway. So unless the HW is representative of what I describe below, a static parent/no-parent setup is preferable. > Or are all those drivers using such a wrapper wrong? I only know of a few drivers that have some variability around that, which resulted in some hacks similar to what you describe. See these patches for example: c351ab7bf2a5 soc/tegra: pmc: Don't create fake interrupt hierarchy levels 8681cc33f817 soc/tegra: pmc: Allow optional irq parent callbacks 986ec63d4482 gpio: tegra186: Allow optional irq parent callbacks 55567976629e genirq/irqdomain: Allow partial trimming of irq_data hierarchy This could have been avoided by restructuring the driver, but would also have had impacts on DT, resulting in something even more horrible. QC's PDC also suffer from a similar hack, which I plan to address once I get this !"£$% machine to boot... But in general, if you need to check for a parent, that's because you are doing something that is either a bit unexpected, or has a *very* broad spectrum (doing something generic enough that it must cope with all possible situations). Thanks, M.
diff --git a/drivers/gpio/gpio-sifive.c b/drivers/gpio/gpio-sifive.c index c54dd08f2cbf..485820e4488c 100644 --- a/drivers/gpio/gpio-sifive.c +++ b/drivers/gpio/gpio-sifive.c @@ -128,6 +128,16 @@ static void sifive_gpio_irq_eoi(struct irq_data *d) irq_chip_eoi_parent(d); } +static int sifive_gpio_irq_set_affinity(struct irq_data *data, + const struct cpumask *dest, + bool force) +{ + if (data->parent_data) + return irq_chip_set_affinity_parent(data, dest, force); + + return -EINVAL; +} + static struct irq_chip sifive_gpio_irqchip = { .name = "sifive-gpio", .irq_set_type = sifive_gpio_irq_set_type, @@ -136,6 +146,7 @@ static struct irq_chip sifive_gpio_irqchip = { .irq_enable = sifive_gpio_irq_enable, .irq_disable = sifive_gpio_irq_disable, .irq_eoi = sifive_gpio_irq_eoi, + .irq_set_affinity = sifive_gpio_irq_set_affinity, }; static int sifive_gpio_child_to_parent_hwirq(struct gpio_chip *gc,
This assigns the .irq_set_affinity to the parent callback. I assume the sifive GPIO can be used in systems with SMP. I used the pattern making the hirerarchy tolerant for missing parent as in Marc's earlier patches. Cc: Yash Shah <yash.shah@sifive.com> Cc: Wesley W. Terpstra <wesley@sifive.com> Suggested-by: Marc Zyngier <maz@kernel.org> Signed-off-by: Linus Walleij <linus.walleij@linaro.org> --- ChangeLog RFT->v1: - Make the affinity setting call return -EINVAL if there is no parent. - Real patch because now we believe in this --- drivers/gpio/gpio-sifive.c | 11 +++++++++++ 1 file changed, 11 insertions(+)