On Thu, 17 Apr 2025 14:10:31 +0200
Boris Brezillon <boris.brezil...@collabora.com> wrote:
> > I can't help feeling we can just simplify this to:
> >
> > u64 mmio_offset = pfile->user_mmio.offset;
> >
> > if (offset >= mmio_offset) {
> > offset -= mmio_offset;
> > offset += DRM_PANTHOR_USER_MMIO_OFFSET;
> > vma->vm_pgoff = offset >> PAGE_SHIFT;
> >
> > ret = panthor_device_mmap_io(ptdev, vma);
> > } else {
> > ret = drm_gem_mmap(filp, vma);
> > }
> >
> > Or even go further and push the offset calculations into
> > panthor_device_mmap_io().
>
> Sure, I can do that.
Actually, if I drop the lock in favor of a
u64 mmio_offset = READ_ONCE(pfile->user_mmio.offset);
I can't move the vm_pgoff/offset adjustement to
panthor_device_mmap_io() because userspace might have called
SET_MMIO_OFFSET in the meantime, thus changing the final offset. One
option would be to pass the mmio_offset to panthor_device_mmap_io(),
but I think I prefer keeping the offset adjustment here if you don't
mind.
