[PATCH 1/2] drm: fix drm_vm for NOMMU builds

[Arnd Bergmann <arnd@arndb.de>]

When building DRM without an MMU, we run into a compile-time error because
pte_wrprotect() is not defined:

drivers/gpu/drm/drm_vm.c: In function 'drm_mmap_dma':
drivers/gpu/drm/drm_vm.c:496:9: error: implicit declaration of function 'pte_wrprotect' [-Werror=implicit-function-declaration]

The line is not meaningful here, so we can simply add another
compile-time check around it.

Fixes: 62a0d98a188c ("drm: allow to use mmuless SoC")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/gpu/drm/drm_vm.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_vm.c b/drivers/gpu/drm/drm_vm.c
index bd311c77c254..038946588ed7 100644
--- a/drivers/gpu/drm/drm_vm.c
+++ b/drivers/gpu/drm/drm_vm.c
@@ -488,7 +488,7 @@ static int drm_mmap_dma(struct file *filp, struct vm_area_struct *vma)
 		vma->vm_flags &= ~(VM_WRITE | VM_MAYWRITE);
 #if defined(__i386__) || defined(__x86_64__)
 		pgprot_val(vma->vm_page_prot) &= ~_PAGE_RW;
-#else
+#elif IS_ENABLED(CONFIG_MMU)
 		/* Ye gads this is ugly.  With more thought
 		   we could move this up higher and use
 		   `protection_map' instead.  */
@@ -572,7 +572,7 @@ static int drm_mmap_locked(struct file *filp, struct vm_area_struct *vma)
 		vma->vm_flags &= ~(VM_WRITE | VM_MAYWRITE);
 #if defined(__i386__) || defined(__x86_64__)
 		pgprot_val(vma->vm_page_prot) &= ~_PAGE_RW;
-#else
+#elif defined (CONFIG_MMU)
 		/* Ye gads this is ugly.  With more thought
 		   we could move this up higher and use
 		   `protection_map' instead.  */
-- 
2.9.0