drm/fb-helper: Add fb_deferred_io support
This adds deferred io support to drm_fb_helper.
The fbdev framebuffer changes are flushed using the callback
(struct drm_framebuffer *)->funcs->dirty() by a dedicated worker
ensuring that it always runs in process context.
For those wondering why we need to be able to handle atomic calling
contexts: Both panic paths and cursor code and fbcon blanking can run
from atomic. See
commit bcb39af4486be07e896fc374a2336bad3104ae0a
Author: Dave Airlie <airlied@redhat.com>
Date: Thu Feb 7 11:19:15 2013 +1000
drm/udl: make usage as a console safer
for where this was originally discovered.
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
[danvet: Augment commit message with why we need to handle atomic
contexts.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1461856717-6476-4-git-send-email-noralf@tronnes.org
diff --git a/include/drm/drm_fb_helper.h b/include/drm/drm_fb_helper.h
index 062723b..5b4aa35 100644
--- a/include/drm/drm_fb_helper.h
+++ b/include/drm/drm_fb_helper.h
@@ -172,6 +172,10 @@
* @funcs: driver callbacks for fb helper
* @fbdev: emulated fbdev device info struct
* @pseudo_palette: fake palette of 16 colors
+ * @dirty_clip: clip rectangle used with deferred_io to accumulate damage to
+ * the screen buffer
+ * @dirty_lock: spinlock protecting @dirty_clip
+ * @dirty_work: worker used to flush the framebuffer
*
* This is the main structure used by the fbdev helpers. Drivers supporting
* fbdev emulation should embedded this into their overall driver structure.
@@ -189,6 +193,9 @@
const struct drm_fb_helper_funcs *funcs;
struct fb_info *fbdev;
u32 pseudo_palette[17];
+ struct drm_clip_rect dirty_clip;
+ spinlock_t dirty_lock;
+ struct work_struct dirty_work;
/**
* @kernel_fb_list:
@@ -245,6 +252,9 @@
void drm_fb_helper_unlink_fbi(struct drm_fb_helper *fb_helper);
+void drm_fb_helper_deferred_io(struct fb_info *info,
+ struct list_head *pagelist);
+
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,
@@ -368,6 +378,11 @@
{
}
+static inline void drm_fb_helper_deferred_io(struct fb_info *info,
+ struct list_head *pagelist)
+{
+}
+
static inline ssize_t drm_fb_helper_sys_read(struct fb_info *info,
char __user *buf, size_t count,
loff_t *ppos)