| Message ID | 20160609182023.13455.82564.stgit@bhelgaas-glaptop2.roam.corp.google.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
On Thu, Jun 09, 2016 at 01:20:23PM -0500, Bjorn Helgaas wrote: > From: Yinghai Lu <yinghai@kernel.org> > > The powerpc-specific __pci_mmap_set_pgprot() does two things: > > 1) Disables write combining for I/O port space mappings > > This only affects procfs mappings. The pci_mmap_resource() sysfs path > only requests write combining for resources with IORESOURCE_PREFETCH > set, which doesn't include I/O resources. > > The only way to request write combining for I/O port space mappings > was via the PCIIOC_WRITE_COMBINE ioctl and the proc_bus_pci_mmap() > path, and we recently changed that path to ignore write combining for > I/O, so this code in powerpc is no longer needed. > > 2) Automatically enables write combining for mappings of prefetchable > resources, even if not requested by the user > > Both procfs (via PCIIOC_MMAP_IS_MEM and PCIIOC_WRITE_COMBINE ioctls) > and sysfs (via "resourceN_wc" files, which are created for resources > with IORESOURCE_PREFETCH) provide ways for the user to map PCI memory > space with write combining. > > Users that desire write combining should use one of those ways instead > of relying on powerpc-specific behavior. > > Remove the powerpc-specific __pci_mmap_set_pgprot(). > > The user-visible effect of this change is that users mapping prefetchable > PCI memory space via procfs without PCIIOC_WRITE_COMBINE or via sysfs > "resourceN" (not "resourceN_wc") will get regular uncacheable mappings > instead of the write combining mappings they used to get. > > The new behavior matches the behavior on all other arches that support > write combining mapping. Powerpc folks, any thoughts on this? It's currently on my pci/resource branch, and I plan to merge it for v4.8 if there are no objections. > [bhelgaas: changelog] > Signed-off-by: Yinghai Lu <yinghai@kernel.org> > Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> > --- > arch/powerpc/kernel/pci-common.c | 37 ++++--------------------------------- > 1 file changed, 4 insertions(+), 33 deletions(-) > > diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c > index 0f7a60f..8c6beb0 100644 > --- a/arch/powerpc/kernel/pci-common.c > +++ b/arch/powerpc/kernel/pci-common.c > @@ -356,36 +356,6 @@ static struct resource *__pci_mmap_make_offset(struct pci_dev *dev, > } > > /* > - * Set vm_page_prot of VMA, as appropriate for this architecture, for a pci > - * device mapping. > - */ > -static pgprot_t __pci_mmap_set_pgprot(struct pci_dev *dev, struct resource *rp, > - pgprot_t protection, > - enum pci_mmap_state mmap_state, > - int write_combine) > -{ > - > - /* Write combine is always 0 on non-memory space mappings. On > - * memory space, if the user didn't pass 1, we check for a > - * "prefetchable" resource. This is a bit hackish, but we use > - * this to workaround the inability of /sysfs to provide a write > - * combine bit > - */ > - if (mmap_state != pci_mmap_mem) > - write_combine = 0; > - else if (write_combine == 0) { > - if (rp->flags & IORESOURCE_PREFETCH) > - write_combine = 1; > - } > - > - /* XXX would be nice to have a way to ask for write-through */ > - if (write_combine) > - return pgprot_noncached_wc(protection); > - else > - return pgprot_noncached(protection); > -} > - > -/* > * This one is used by /dev/mem and fbdev who have no clue about the > * PCI device, it tries to find the PCI device first and calls the > * above routine > @@ -458,9 +428,10 @@ int pci_mmap_page_range(struct pci_dev *dev, struct vm_area_struct *vma, > return -EINVAL; > > vma->vm_pgoff = offset >> PAGE_SHIFT; > - vma->vm_page_prot = __pci_mmap_set_pgprot(dev, rp, > - vma->vm_page_prot, > - mmap_state, write_combine); > + if (write_combine) > + vma->vm_page_prot = pgprot_noncached_wc(vma->vm_page_prot); > + else > + vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); > > ret = remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff, > vma->vm_end - vma->vm_start, vma->vm_page_prot); > > -- > To unsubscribe from this list: send the line "unsubscribe linux-pci" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c index 0f7a60f..8c6beb0 100644 --- a/arch/powerpc/kernel/pci-common.c +++ b/arch/powerpc/kernel/pci-common.c @@ -356,36 +356,6 @@ static struct resource *__pci_mmap_make_offset(struct pci_dev *dev, } /* - * Set vm_page_prot of VMA, as appropriate for this architecture, for a pci - * device mapping. - */ -static pgprot_t __pci_mmap_set_pgprot(struct pci_dev *dev, struct resource *rp, - pgprot_t protection, - enum pci_mmap_state mmap_state, - int write_combine) -{ - - /* Write combine is always 0 on non-memory space mappings. On - * memory space, if the user didn't pass 1, we check for a - * "prefetchable" resource. This is a bit hackish, but we use - * this to workaround the inability of /sysfs to provide a write - * combine bit - */ - if (mmap_state != pci_mmap_mem) - write_combine = 0; - else if (write_combine == 0) { - if (rp->flags & IORESOURCE_PREFETCH) - write_combine = 1; - } - - /* XXX would be nice to have a way to ask for write-through */ - if (write_combine) - return pgprot_noncached_wc(protection); - else - return pgprot_noncached(protection); -} - -/* * This one is used by /dev/mem and fbdev who have no clue about the * PCI device, it tries to find the PCI device first and calls the * above routine @@ -458,9 +428,10 @@ int pci_mmap_page_range(struct pci_dev *dev, struct vm_area_struct *vma, return -EINVAL; vma->vm_pgoff = offset >> PAGE_SHIFT; - vma->vm_page_prot = __pci_mmap_set_pgprot(dev, rp, - vma->vm_page_prot, - mmap_state, write_combine); + if (write_combine) + vma->vm_page_prot = pgprot_noncached_wc(vma->vm_page_prot); + else + vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); ret = remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff, vma->vm_end - vma->vm_start, vma->vm_page_prot);