[PATCH 2/3] Define fb_open_adj_file()

['Max Staudt]

From: Max Staudt <msta...@suse.de>

This callback from fb_open() allows a fbdev driver to adjust things such
as file->f_mapping to better represent the internal structures.

This is needed to allow TTM drivers using ttm_fbdev_mmap() to properly
set file->f_mapping to TTM's address_space from bo->bdev->dev_mapping,
as is done form /dev/drm/card* in drm_open().

Currently, bochsdrmfb is the only driver requiring this, and this
patch is a prerequisite to implement this in bochsdrmfb.

Signed-off-by: Max Staudt <mstaudt at suse.de>
---
 drivers/video/fbdev/core/fbmem.c | 13 +++++++++++++
 include/linux/fb.h               |  7 +++++++
 2 files changed, 20 insertions(+)

diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c
index 913c496..ff5000e 100644
--- a/drivers/video/fbdev/core/fbmem.c
+++ b/drivers/video/fbdev/core/fbmem.c
@@ -1471,6 +1471,19 @@ __releases(&info->lock)
        if (info->fbdefio)
                fb_deferred_io_open(info, inode, file);
 #endif
+       if (info->fbops->fb_open_adj_file) {
+               res = info->fbops->fb_open_adj_file(info, file);
+               if (res) {
+                       /* If we got here, we also want to undo anything
+                        * that fbops->fb_open() may have done.
+                        */
+                       if (info->fbops->fb_release)
+                               info->fbops->fb_release(info,1);
+
+                       module_put(info->fbops->owner);
+                       goto out;
+               }
+       }
 out:
        mutex_unlock(&info->lock);
        if (res)
diff --git a/include/linux/fb.h b/include/linux/fb.h
index dfe8835..4131496 100644
--- a/include/linux/fb.h
+++ b/include/linux/fb.h
@@ -320,6 +320,13 @@ struct fb_ops {
        /* called at KDB enter and leave time to prepare the console */
        int (*fb_debug_enter)(struct fb_info *info);
        int (*fb_debug_leave)(struct fb_info *info);
+
+       /* Called after fb_open() to adjust mappings when using
+        * complex backends such as TTM.
+        * For example, the bochsdrmfb driver needs to adjust
+        * file->f_mapping so it can use ttm_fbdev_mmap().
+        */
+       int (*fb_open_adj_file)(struct fb_info *info, struct file *file);
 };

 #ifdef CONFIG_FB_TILEBLITTING
-- 
2.6.6