| Message ID | 20220429135108.2781579-3-schnelle@linux.ibm.com (mailing list archive) |
|---|---|
| State | Handled Elsewhere |
| Headers | show |
| Series | Kconfig: Introduce HAS_IOPORT config option | expand |
On Fri, Apr 29, 2022 at 3:51 PM Niklas Schnelle <schnelle@linux.ibm.com> wrote: > > In a future patch HAS_IOPORT=n will result in inb()/outb() and friends > not being declared. As ACPI always uses I/O port access we simply depend > on HAS_IOPORT. > > Co-developed-by: Arnd Bergmann <arnd@kernel.org> > Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com> > --- > drivers/acpi/Kconfig | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig > index 1e34f846508f..8ad0d168004c 100644 > --- a/drivers/acpi/Kconfig > +++ b/drivers/acpi/Kconfig > @@ -5,6 +5,7 @@ > > config ARCH_SUPPORTS_ACPI > bool > + depends on HAS_IOPORT This and the analogous PNP change are both fine with me. Thanks! > > menuconfig ACPI > bool "ACPI (Advanced Configuration and Power Interface) Support" > -- > 2.32.0 >
On Fri, Apr 29, 2022 at 03:50:00PM +0200, Niklas Schnelle wrote: > In a future patch HAS_IOPORT=n will result in inb()/outb() and friends > not being declared. As ACPI always uses I/O port access we simply depend > on HAS_IOPORT. CONFIG_ACPI depends on ARCH_SUPPORTS_ACPI, which is only set by arm64, ia64, and x86, all of which support I/O port access. So does this actually solve a problem? I wouldn't think you'd be able to build ACPI on s390 even without this patch. "ACPI always uses I/O port access" is a pretty broad brush, and it would be useful to know specifically what the dependencies are. Many ACPI hardware accesses use acpi_hw_read()/acpi_hw_write(), which use either MMIO or I/O port accesses depending on what the firmware told us. > Co-developed-by: Arnd Bergmann <arnd@kernel.org> > Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com> > --- > drivers/acpi/Kconfig | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig > index 1e34f846508f..8ad0d168004c 100644 > --- a/drivers/acpi/Kconfig > +++ b/drivers/acpi/Kconfig > @@ -5,6 +5,7 @@ > > config ARCH_SUPPORTS_ACPI > bool > + depends on HAS_IOPORT > > menuconfig ACPI > bool "ACPI (Advanced Configuration and Power Interface) Support" > -- > 2.32.0 >
On Wed, May 4, 2022 at 7:53 PM Bjorn Helgaas <helgaas@kernel.org> wrote: > > On Fri, Apr 29, 2022 at 03:50:00PM +0200, Niklas Schnelle wrote: > > In a future patch HAS_IOPORT=n will result in inb()/outb() and friends > > not being declared. As ACPI always uses I/O port access we simply depend > > on HAS_IOPORT. > > CONFIG_ACPI depends on ARCH_SUPPORTS_ACPI, which is only set by arm64, > ia64, and x86, all of which support I/O port access. So does this > actually solve a problem? I wouldn't think you'd be able to build > ACPI on s390 even without this patch. > "ACPI always uses I/O port access" is a pretty broad brush, and it > would be useful to know specifically what the dependencies are. > > Many ACPI hardware accesses use acpi_hw_read()/acpi_hw_write(), which > use either MMIO or I/O port accesses depending on what the firmware > told us. I think this came from my original prototype of the series where I tested it out on arm64 with HAS_IOPORT disabled. I would like to hide the definition of inb()/outb() from include/asm-generic/io.h whenever CONFIG_HAS_IOPORT is not set, and I was prototyping this on arm64. There are uses of inb()/outb() in drivers/acpi/ec.c and drivers/acpi/osl.c, which in turn are not optional in ACPI, so it seems that those are required. If we want to allow building arm64 without HAS_IOPORT for some reason, that means either force-disabling ACPI as well, or changin ACPI to not rely on port I/O. I think it's fine to leave that as a problem for whoever wants to make HAS_IOPORT optional in the future, and drop the dependency here. Arnd
On Wed, 2022-05-04 at 21:58 +0200, Arnd Bergmann wrote: > On Wed, May 4, 2022 at 7:53 PM Bjorn Helgaas <helgaas@kernel.org> wrote: > > On Fri, Apr 29, 2022 at 03:50:00PM +0200, Niklas Schnelle wrote: > > > In a future patch HAS_IOPORT=n will result in inb()/outb() and friends > > > not being declared. As ACPI always uses I/O port access we simply depend > > > on HAS_IOPORT. > > > > CONFIG_ACPI depends on ARCH_SUPPORTS_ACPI, which is only set by arm64, > > ia64, and x86, all of which support I/O port access. So does this > > actually solve a problem? I wouldn't think you'd be able to build > > ACPI on s390 even without this patch. > > "ACPI always uses I/O port access" is a pretty broad brush, and it > > would be useful to know specifically what the dependencies are. > > > > Many ACPI hardware accesses use acpi_hw_read()/acpi_hw_write(), which > > use either MMIO or I/O port accesses depending on what the firmware > > told us. > > I think this came from my original prototype of the series where I tested it > out on arm64 with HAS_IOPORT disabled. I would like to hide the definition > of inb()/outb() from include/asm-generic/io.h whenever CONFIG_HAS_IOPORT > is not set, and I was prototyping this on arm64. > > There are uses of inb()/outb() in drivers/acpi/ec.c and drivers/acpi/osl.c, > which in turn are not optional in ACPI, so it seems that those are > required. > > If we want to allow building arm64 without HAS_IOPORT for some reason, > that means either force-disabling ACPI as well, or changin ACPI to not > rely on port I/O. I think it's fine to leave that as a problem for whoever > wants to make HAS_IOPORT optional in the future, and drop the > dependency here. > > Arnd I'll improve the commit message to make the dependency on HAS_IOPORT more clear. I also agree with Arnd that since all architectures where ACPI is useful have I/O ports making it work without I/O port access compiled in is for another day.
On Thu, May 05, 2022 at 10:20:28AM +0200, Niklas Schnelle wrote: > On Wed, 2022-05-04 at 21:58 +0200, Arnd Bergmann wrote: > > On Wed, May 4, 2022 at 7:53 PM Bjorn Helgaas <helgaas@kernel.org> wrote: > > > On Fri, Apr 29, 2022 at 03:50:00PM +0200, Niklas Schnelle wrote: > > > > In a future patch HAS_IOPORT=n will result in inb()/outb() and friends > > > > not being declared. As ACPI always uses I/O port access we simply depend > > > > on HAS_IOPORT. > > > > > > CONFIG_ACPI depends on ARCH_SUPPORTS_ACPI, which is only set by arm64, > > > ia64, and x86, all of which support I/O port access. So does this > > > actually solve a problem? I wouldn't think you'd be able to build > > > ACPI on s390 even without this patch. > > > "ACPI always uses I/O port access" is a pretty broad brush, and it > > > would be useful to know specifically what the dependencies are. > > > > > > Many ACPI hardware accesses use acpi_hw_read()/acpi_hw_write(), which > > > use either MMIO or I/O port accesses depending on what the firmware > > > told us. > > > > I think this came from my original prototype of the series where I tested it > > out on arm64 with HAS_IOPORT disabled. I would like to hide the definition > > of inb()/outb() from include/asm-generic/io.h whenever CONFIG_HAS_IOPORT > > is not set, and I was prototyping this on arm64. > > > > There are uses of inb()/outb() in drivers/acpi/ec.c and drivers/acpi/osl.c, > > which in turn are not optional in ACPI, so it seems that those are > > required. > > > > If we want to allow building arm64 without HAS_IOPORT for some reason, > > that means either force-disabling ACPI as well, or changin ACPI to not > > rely on port I/O. I think it's fine to leave that as a problem for whoever > > wants to make HAS_IOPORT optional in the future, and drop the > > dependency here. > > I'll improve the commit message to make the dependency on HAS_IOPORT > more clear. I also agree with Arnd that since all architectures where > ACPI is useful have I/O ports making it work without I/O port access > compiled in is for another day. I don't really see the point of including this patch at all. It doesn't solve any existing problem.
diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig index 1e34f846508f..8ad0d168004c 100644 --- a/drivers/acpi/Kconfig +++ b/drivers/acpi/Kconfig @@ -5,6 +5,7 @@ config ARCH_SUPPORTS_ACPI bool + depends on HAS_IOPORT menuconfig ACPI bool "ACPI (Advanced Configuration and Power Interface) Support"
In a future patch HAS_IOPORT=n will result in inb()/outb() and friends not being declared. As ACPI always uses I/O port access we simply depend on HAS_IOPORT. Co-developed-by: Arnd Bergmann <arnd@kernel.org> Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com> --- drivers/acpi/Kconfig | 1 + 1 file changed, 1 insertion(+)