Hi,
On Wed, Mar 15, 2017 at 05:17:46PM +0000, David Woodhouse wrote:
> From: Brijesh Singh <brijess@xxxxxxxxxx>
>
> To support pci resource mapping from userspace, pci_mmap_page_range
> implementation must be done for that platform. This support was
> broken for arm64.
>
> This patch copies existing implementation from arm to
> enable sysfs mmap.
It's not so much "broken" as "not currently supported".
[...]
> +#define HAVE_PCI_MMAP
> +extern int pci_mmap_page_range(struct pci_dev *dev, struct vm_area_struct *vma,
> + enum pci_mmap_state mmap_state, int write_combine);
> +
Per the prior attempt at this [1], we only want to expose the sysfs
interface, and not the legacy procfs interface, and need the two
decoupled [2].
... or has something changed in the mean time, so that this only exposes
the sysfs interface?
[...]
> +int pci_mmap_page_range(struct pci_dev *dev, struct vm_area_struct *vma,
> + enum pci_mmap_state mmap_state, int write_combine)
> +{
> + if (mmap_state == pci_mmap_io)
> + return -EINVAL;
> +
> + if (write_combine)
> + vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
> + else
> + vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
... as per Will's comment in [3], the latter of these should use
pgprot_device.
Thanks,
Mark.
[1] http://lists.infradead.org/pipermail/linux-arm-kernel/2016-April/421948.html
[2] http://lists.infradead.org/pipermail/linux-arm-kernel/2016-April/423083.html
[3] http://lists.infradead.org/pipermail/linux-arm-kernel/2016-April/422571.html
