* [PATCH v2 1/2] kconfig.h: Add IF_ENABLED() macro
@ 2020-12-13 23:54 Paul Cercueil
2020-12-13 23:54 ` [PATCH v2 2/2] pinctrl: ingenic: Only support SoCs enabled in config Paul Cercueil
` (2 more replies)
0 siblings, 3 replies; 6+ messages in thread
From: Paul Cercueil @ 2020-12-13 23:54 UTC (permalink / raw)
To: Linus Walleij
Cc: Arnd Bergmann, od, linux-gpio, linux-kernel, Zhou Yanjie, Paul Cercueil
IF_ENABLED(CONFIG_FOO, ptr) evaluates to (ptr) if CONFIG_FOO is set to 'y'
or 'm', NULL otherwise. The (ptr) argument must be a pointer.
The IF_ENABLED() macro can be very useful to help GCC drop dead code.
For instance, consider the following:
#ifdef CONFIG_FOO_SUSPEND
static int foo_suspend(struct device *dev)
{
...
}
#endif
static struct pm_ops foo_ops = {
#ifdef CONFIG_FOO_SUSPEND
.suspend = foo_suspend,
#endif
};
While this works, the foo_suspend() macro is compiled conditionally,
only when CONFIG_FOO_SUSPEND is set. This is problematic, as there could
be a build bug in this function, we wouldn't have a way to know unless
the config option is set.
An alternative is to declare foo_suspend() always, but mark it as maybe
unused:
static int __maybe_unused foo_suspend(struct device *dev)
{
...
}
static struct pm_ops foo_ops = {
#ifdef CONFIG_FOO_SUSPEND
.suspend = foo_suspend,
#endif
};
Again, this works, but the __maybe_unused attribute is required to
instruct the compiler that the function may not be referenced anywhere,
and is safe to remove without making a fuss about it. This makes the
programmer responsible for tagging the functions that can be
garbage-collected.
With this patch, it is now possible to write the following:
static int foo_suspend(struct device *dev)
{
...
}
static struct pm_ops foo_ops = {
.suspend = IF_ENABLED(CONFIG_FOO_SUSPEND, foo_suspend),
};
The foo_suspend() function will now be automatically dropped by the
compiler, and it does not require any specific attribute.
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
---
Notes:
v2: Only add IF_ENABLED() and don't verify that the argument is a
pointer; since the second argument of the ?: ternary operator
is NULL, the compiler should issue an error if the other
argument is not a pointer.
include/linux/kconfig.h | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/include/linux/kconfig.h b/include/linux/kconfig.h
index 9d12c970f18f..e78e17a76dc9 100644
--- a/include/linux/kconfig.h
+++ b/include/linux/kconfig.h
@@ -72,4 +72,10 @@
*/
#define IS_ENABLED(option) __or(IS_BUILTIN(option), IS_MODULE(option))
+/*
+ * IF_ENABLED(CONFIG_FOO, ptr) evaluates to (ptr) if CONFIG_FOO is set to 'y'
+ * or 'm', NULL otherwise.
+ */
+#define IF_ENABLED(option, ptr) (IS_ENABLED(option) ? (ptr) : NULL)
+
#endif /* __LINUX_KCONFIG_H */
--
2.29.2
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH v2 2/2] pinctrl: ingenic: Only support SoCs enabled in config
2020-12-13 23:54 [PATCH v2 1/2] kconfig.h: Add IF_ENABLED() macro Paul Cercueil
@ 2020-12-13 23:54 ` Paul Cercueil
2020-12-14 9:05 ` [PATCH v2 1/2] kconfig.h: Add IF_ENABLED() macro Linus Walleij
2021-01-18 15:14 ` Linus Walleij
2 siblings, 0 replies; 6+ messages in thread
From: Paul Cercueil @ 2020-12-13 23:54 UTC (permalink / raw)
To: Linus Walleij
Cc: Arnd Bergmann, od, linux-gpio, linux-kernel, Zhou Yanjie, Paul Cercueil
Tested on a JZ4740 system (ARCH=mips make qi_lb60_defconfig), this saves
about 14 KiB, by allowing the compiler to garbage-collect all the
functions and tables that correspond to SoCs that were disabled in the
config.
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
---
Notes:
v2: Drop <linux/if_enabled.h> include
drivers/pinctrl/pinctrl-ingenic.c | 60 ++++++++++++++++++++++++-------
1 file changed, 48 insertions(+), 12 deletions(-)
diff --git a/drivers/pinctrl/pinctrl-ingenic.c b/drivers/pinctrl/pinctrl-ingenic.c
index a14938a7cc30..cb8fa261110a 100644
--- a/drivers/pinctrl/pinctrl-ingenic.c
+++ b/drivers/pinctrl/pinctrl-ingenic.c
@@ -2384,6 +2384,12 @@ static int __init ingenic_pinctrl_probe(struct platform_device *pdev)
unsigned int i;
int err;
+ chip_info = of_device_get_match_data(dev);
+ if (!chip_info) {
+ dev_err(dev, "Unsupported SoC\n");
+ return -EINVAL;
+ }
+
jzpc = devm_kzalloc(dev, sizeof(*jzpc), GFP_KERNEL);
if (!jzpc)
return -ENOMEM;
@@ -2400,7 +2406,7 @@ static int __init ingenic_pinctrl_probe(struct platform_device *pdev)
}
jzpc->dev = dev;
- jzpc->info = chip_info = of_device_get_match_data(dev);
+ jzpc->info = chip_info;
pctl_desc = devm_kzalloc(&pdev->dev, sizeof(*pctl_desc), GFP_KERNEL);
if (!pctl_desc)
@@ -2470,17 +2476,47 @@ static int __init ingenic_pinctrl_probe(struct platform_device *pdev)
}
static const struct of_device_id ingenic_pinctrl_of_match[] = {
- { .compatible = "ingenic,jz4740-pinctrl", .data = &jz4740_chip_info },
- { .compatible = "ingenic,jz4725b-pinctrl", .data = &jz4725b_chip_info },
- { .compatible = "ingenic,jz4760-pinctrl", .data = &jz4760_chip_info },
- { .compatible = "ingenic,jz4760b-pinctrl", .data = &jz4760_chip_info },
- { .compatible = "ingenic,jz4770-pinctrl", .data = &jz4770_chip_info },
- { .compatible = "ingenic,jz4780-pinctrl", .data = &jz4780_chip_info },
- { .compatible = "ingenic,x1000-pinctrl", .data = &x1000_chip_info },
- { .compatible = "ingenic,x1000e-pinctrl", .data = &x1000_chip_info },
- { .compatible = "ingenic,x1500-pinctrl", .data = &x1500_chip_info },
- { .compatible = "ingenic,x1830-pinctrl", .data = &x1830_chip_info },
- {},
+ {
+ .compatible = "ingenic,jz4740-pinctrl",
+ .data = IF_ENABLED(CONFIG_MACH_JZ4740, &jz4740_chip_info)
+ },
+ {
+ .compatible = "ingenic,jz4725b-pinctrl",
+ .data = IF_ENABLED(CONFIG_MACH_JZ4725B, &jz4725b_chip_info)
+ },
+ {
+ .compatible = "ingenic,jz4760-pinctrl",
+ .data = IF_ENABLED(CONFIG_MACH_JZ4760, &jz4760_chip_info)
+ },
+ {
+ .compatible = "ingenic,jz4760b-pinctrl",
+ .data = IF_ENABLED(CONFIG_MACH_JZ4760, &jz4760_chip_info)
+ },
+ {
+ .compatible = "ingenic,jz4770-pinctrl",
+ .data = IF_ENABLED(CONFIG_MACH_JZ4770, &jz4770_chip_info)
+ },
+ {
+ .compatible = "ingenic,jz4780-pinctrl",
+ .data = IF_ENABLED(CONFIG_MACH_JZ4780, &jz4780_chip_info)
+ },
+ {
+ .compatible = "ingenic,x1000-pinctrl",
+ .data = IF_ENABLED(CONFIG_MACH_X1000, &x1000_chip_info)
+ },
+ {
+ .compatible = "ingenic,x1000e-pinctrl",
+ .data = IF_ENABLED(CONFIG_MACH_X1000, &x1000_chip_info)
+ },
+ {
+ .compatible = "ingenic,x1500-pinctrl",
+ .data = IF_ENABLED(CONFIG_MACH_X1500, &x1500_chip_info)
+ },
+ {
+ .compatible = "ingenic,x1830-pinctrl",
+ .data = IF_ENABLED(CONFIG_MACH_X1830, &x1830_chip_info)
+ },
+ { /* sentinel */ },
};
static struct platform_driver ingenic_pinctrl_driver = {
--
2.29.2
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2 1/2] kconfig.h: Add IF_ENABLED() macro
2020-12-13 23:54 [PATCH v2 1/2] kconfig.h: Add IF_ENABLED() macro Paul Cercueil
2020-12-13 23:54 ` [PATCH v2 2/2] pinctrl: ingenic: Only support SoCs enabled in config Paul Cercueil
@ 2020-12-14 9:05 ` Linus Walleij
2021-01-11 8:45 ` Paul Cercueil
2021-01-18 15:14 ` Linus Walleij
2 siblings, 1 reply; 6+ messages in thread
From: Linus Walleij @ 2020-12-14 9:05 UTC (permalink / raw)
To: Paul Cercueil
Cc: Arnd Bergmann, od, open list:GPIO SUBSYSTEM, linux-kernel, Zhou Yanjie
On Mon, Dec 14, 2020 at 12:54 AM Paul Cercueil <paul@crapouillou.net> wrote:
> IF_ENABLED(CONFIG_FOO, ptr) evaluates to (ptr) if CONFIG_FOO is set to 'y'
> or 'm', NULL otherwise. The (ptr) argument must be a pointer.
>
> The IF_ENABLED() macro can be very useful to help GCC drop dead code.
I can apply this with the other patch to the pinctrl subsystem if Arnd or
someone else who is good at KConfig provides an ACK.
Yours,
Linus Walleij
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2 1/2] kconfig.h: Add IF_ENABLED() macro
2020-12-14 9:05 ` [PATCH v2 1/2] kconfig.h: Add IF_ENABLED() macro Linus Walleij
@ 2021-01-11 8:45 ` Paul Cercueil
2021-01-15 11:47 ` Arnd Bergmann
0 siblings, 1 reply; 6+ messages in thread
From: Paul Cercueil @ 2021-01-11 8:45 UTC (permalink / raw)
To: Linus Walleij, Arnd Bergmann
Cc: od, GPIO SUBSYSTEM, linux-kernel, Zhou Yanjie
Hi,
Le lun. 14 déc. 2020 à 10:05, Linus Walleij
<linus.walleij@linaro.org> a écrit :
> On Mon, Dec 14, 2020 at 12:54 AM Paul Cercueil <paul@crapouillou.net>
> wrote:
>
>> IF_ENABLED(CONFIG_FOO, ptr) evaluates to (ptr) if CONFIG_FOO is set
>> to 'y'
>> or 'm', NULL otherwise. The (ptr) argument must be a pointer.
>>
>> The IF_ENABLED() macro can be very useful to help GCC drop dead
>> code.
>
> I can apply this with the other patch to the pinctrl subsystem if
> Arnd or
> someone else who is good at KConfig provides an ACK.
Arnd? Any feedback?
Cheers,
-Paul
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2 1/2] kconfig.h: Add IF_ENABLED() macro
2021-01-11 8:45 ` Paul Cercueil
@ 2021-01-15 11:47 ` Arnd Bergmann
0 siblings, 0 replies; 6+ messages in thread
From: Arnd Bergmann @ 2021-01-15 11:47 UTC (permalink / raw)
To: Paul Cercueil
Cc: Linus Walleij, od, GPIO SUBSYSTEM, linux-kernel, Zhou Yanjie
On Mon, Jan 11, 2021 at 9:45 AM Paul Cercueil <paul@crapouillou.net> wrote:
>
> Hi,
>
> Le lun. 14 déc. 2020 à 10:05, Linus Walleij
> <linus.walleij@linaro.org> a écrit :
> > On Mon, Dec 14, 2020 at 12:54 AM Paul Cercueil <paul@crapouillou.net>
> > wrote:
> >
> >> IF_ENABLED(CONFIG_FOO, ptr) evaluates to (ptr) if CONFIG_FOO is set
> >> to 'y'
> >> or 'm', NULL otherwise. The (ptr) argument must be a pointer.
> >>
> >> The IF_ENABLED() macro can be very useful to help GCC drop dead
> >> code.
Looks great! Thanks a lot for getting this sorted.
> > I can apply this with the other patch to the pinctrl subsystem if
> > Arnd or someone else who is good at KConfig provides an ACK.
Yes, please do.
Acked-by: Arnd Bergmann <arnd@arndb.de>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2 1/2] kconfig.h: Add IF_ENABLED() macro
2020-12-13 23:54 [PATCH v2 1/2] kconfig.h: Add IF_ENABLED() macro Paul Cercueil
2020-12-13 23:54 ` [PATCH v2 2/2] pinctrl: ingenic: Only support SoCs enabled in config Paul Cercueil
2020-12-14 9:05 ` [PATCH v2 1/2] kconfig.h: Add IF_ENABLED() macro Linus Walleij
@ 2021-01-18 15:14 ` Linus Walleij
2 siblings, 0 replies; 6+ messages in thread
From: Linus Walleij @ 2021-01-18 15:14 UTC (permalink / raw)
To: Paul Cercueil
Cc: Arnd Bergmann, od, open list:GPIO SUBSYSTEM, linux-kernel, Zhou Yanjie
Both patches applied!
Yours,
Linus Walleij
^ permalink raw reply [flat|nested] 6+ messages in thread
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2020-12-13 23:54 [PATCH v2 1/2] kconfig.h: Add IF_ENABLED() macro Paul Cercueil
2020-12-13 23:54 ` [PATCH v2 2/2] pinctrl: ingenic: Only support SoCs enabled in config Paul Cercueil
2020-12-14 9:05 ` [PATCH v2 1/2] kconfig.h: Add IF_ENABLED() macro Linus Walleij
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