[PATCH 1/2] drm/gem: don't force writecombine mmap'ing

From: Rob Clark
Date: Tue Jul 16 2019 - 12:44:37 EST


From: Rob Clark <robdclark@xxxxxxxxxxxx>

The driver should be in control of this.

Signed-off-by: Rob Clark <robdclark@xxxxxxxxxxxx>
---
It is possible that this was masking bugs (ie. not setting appropriate
pgprot) in drivers. I don't have a particularly good idea for tracking
those down (since I don't have the hw for most drivers). Unless someone
has a better idea, maybe land this and let driver maintainers fix any
potential fallout in their drivers?

This is necessary for the next patch to fix VGEM brokenness on arm.

drivers/gpu/drm/drm_gem.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
index 8a55f71325b1..7d6242cc69f2 100644
--- a/drivers/gpu/drm/drm_gem.c
+++ b/drivers/gpu/drm/drm_gem.c
@@ -1110,7 +1110,7 @@ int drm_gem_mmap_obj(struct drm_gem_object *obj, unsigned long obj_size,

vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
vma->vm_private_data = obj;
- vma->vm_page_prot = pgprot_writecombine(vm_get_page_prot(vma->vm_flags));
+ vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
vma->vm_page_prot = pgprot_decrypted(vma->vm_page_prot);

/* Take a ref for this mapping of the object, so that the fault
--
2.21.0