[PATCH 7/9] drm/fb-helper: Provide fbdev deferred-I/O helpers

[Thomas Zimmermann <tzimmermann@suse.de>]

Add drm_fb_helper_vm_page_mkwrite(), a helper to track pages written
by fbdev userspace. DRM drivers should use this function to implement
fbdev deferred I/O.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/drm_fb_helper.c | 10 ++++++++++
 include/drm/drm_fb_helper.h     |  9 +++++++++
 2 files changed, 19 insertions(+)

diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 9d1140a789f4..6203f5ab33af 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -760,6 +760,16 @@ void drm_fb_helper_deferred_io(struct fb_info *info,
 }
 EXPORT_SYMBOL(drm_fb_helper_deferred_io);
 
+vm_fault_t drm_fb_helper_vm_page_mkwrite(struct drm_fb_helper *fb_helper, struct vm_fault *vmf)
+{
+	struct fb_info *info = fb_helper->fbdev;
+
+	if (!info->fbdefio)
+		return 0;
+	return fb_deferred_io_page_mkwrite(info, vmf);
+}
+EXPORT_SYMBOL(drm_fb_helper_vm_page_mkwrite);
+
 /**
  * drm_fb_helper_sys_read - wrapper around fb_sys_read
  * @info: fb_info struct pointer
diff --git a/include/drm/drm_fb_helper.h b/include/drm/drm_fb_helper.h
index 3af4624368d8..8994c65f0b5a 100644
--- a/include/drm/drm_fb_helper.h
+++ b/include/drm/drm_fb_helper.h
@@ -232,6 +232,9 @@ void drm_fb_helper_fill_info(struct fb_info *info,
 void drm_fb_helper_deferred_io(struct fb_info *info,
 			       struct list_head *pagelist);
 
+vm_fault_t drm_fb_helper_vm_page_mkwrite(struct drm_fb_helper *fb_helper,
+					 struct vm_fault *vmf);
+
 ssize_t drm_fb_helper_sys_read(struct fb_info *info, char __user *buf,
 			       size_t count, loff_t *ppos);
 ssize_t drm_fb_helper_sys_write(struct fb_info *info, const char __user *buf,
@@ -355,6 +358,12 @@ static inline void drm_fb_helper_deferred_io(struct fb_info *info,
 {
 }
 
+static inline vm_fault_t drm_fb_helper_vm_page_mkwrite(struct drm_fb_helper *fb_helper,
+						       struct vm_fault *vmf)
+{
+	return 0;
+}
+
 static inline int drm_fb_helper_defio_init(struct drm_fb_helper *fb_helper)
 {
 	return -ENODEV;
-- 
2.35.1