s390/pci: clarify comment in s390_mmio_read/write (4631f3ca) · Commits · 戴 / test

arch/s390/pci/pci_mmio.c

+12 −8

Original line number	Diff line number	Diff line
		@@ -155,10 +155,12 @@ SYSCALL_DEFINE3(s390_pci_mmio_write, unsigned long, mmio_addr,
		return -EINVAL;

		/*
		* Only support read access to MIO capable devices on a MIO enabled
		* system. Otherwise we would have to check for every address if it is
		* a special ZPCI_ADDR and we would have to do a get_pfn() which we
		* don't need for MIO capable devices.
		* We only support write access to MIO capable devices if we are on
		* a MIO enabled system. Otherwise we would have to check for every
		* address if it is a special ZPCI_ADDR and would have to do
		* a get_pfn() which we don't need for MIO capable devices. Currently
		* ISM devices are the only devices without MIO support and there is no
		* known need for accessing these from userspace.
		*/
		if (static_branch_likely(&have_mio)) {
		ret = __memcpy_toio_inuser((void __iomem *) mmio_addr,
		@@ -282,10 +284,12 @@ SYSCALL_DEFINE3(s390_pci_mmio_read, unsigned long, mmio_addr,
		return -EINVAL;

		/*
		* Only support write access to MIO capable devices on a MIO enabled
		* system. Otherwise we would have to check for every address if it is
		* a special ZPCI_ADDR and we would have to do a get_pfn() which we
		* don't need for MIO capable devices.
		* We only support read access to MIO capable devices if we are on
		* a MIO enabled system. Otherwise we would have to check for every
		* address if it is a special ZPCI_ADDR and would have to do
		* a get_pfn() which we don't need for MIO capable devices. Currently
		* ISM devices are the only devices without MIO support and there is no
		* known need for accessing these from userspace.
		*/
		if (static_branch_likely(&have_mio)) {
		ret = __memcpy_fromio_inuser(

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