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/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index f2a74d0..414c79b 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -52,6 +52,7 @@
select FB_CFB_FILLRECT
select FB_CFB_COPYAREA
select FB_CFB_IMAGEBLIT
+ select FB_DEFERRED_IO
help
FBDEV helpers for KMS drivers.
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 855108e..62f849f 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -84,6 +84,15 @@
* and set up an initial configuration using the detected hardware, drivers
* should call drm_fb_helper_single_add_all_connectors() followed by
* drm_fb_helper_initial_config().
+ *
+ * If CONFIG_FB_DEFERRED_IO is enabled and &drm_framebuffer_funcs ->dirty is
+ * set, the drm_fb_helper_{cfb,sys}_{write,fillrect,copyarea,imageblit}
+ * functions will accumulate changes and schedule &fb_helper .dirty_work to run
+ * right away. This worker then calls the dirty() function ensuring that it
+ * will always run in process context since the fb_*() function could be
+ * running in atomic context. If drm_fb_helper_deferred_io() is used as the
+ * deferred_io callback it will also schedule dirty_work with the damage
+ * collected from the mmap page writes.
*/
/**
@@ -637,6 +646,23 @@
kfree(helper->crtc_info);
}
+static void drm_fb_helper_dirty_work(struct work_struct *work)
+{
+ struct drm_fb_helper *helper = container_of(work, struct drm_fb_helper,
+ dirty_work);
+ struct drm_clip_rect *clip = &helper->dirty_clip;
+ struct drm_clip_rect clip_copy;
+ unsigned long flags;
+
+ spin_lock_irqsave(&helper->dirty_lock, flags);
+ clip_copy = *clip;
+ clip->x1 = clip->y1 = ~0;
+ clip->x2 = clip->y2 = 0;
+ spin_unlock_irqrestore(&helper->dirty_lock, flags);
+
+ helper->fb->funcs->dirty(helper->fb, NULL, 0, 0, &clip_copy, 1);
+}
+
/**
* drm_fb_helper_prepare - setup a drm_fb_helper structure
* @dev: DRM device
@@ -650,6 +676,9 @@
const struct drm_fb_helper_funcs *funcs)
{
INIT_LIST_HEAD(&helper->kernel_fb_list);
+ spin_lock_init(&helper->dirty_lock);
+ INIT_WORK(&helper->dirty_work, drm_fb_helper_dirty_work);
+ helper->dirty_clip.x1 = helper->dirty_clip.y1 = ~0;
helper->funcs = funcs;
helper->dev = dev;
}
@@ -834,6 +863,59 @@
}
EXPORT_SYMBOL(drm_fb_helper_unlink_fbi);
+static void drm_fb_helper_dirty(struct fb_info *info, u32 x, u32 y,
+ u32 width, u32 height)
+{
+ struct drm_fb_helper *helper = info->par;
+ struct drm_clip_rect *clip = &helper->dirty_clip;
+ unsigned long flags;
+
+ if (!helper->fb->funcs->dirty)
+ return;
+
+ spin_lock_irqsave(&helper->dirty_lock, flags);
+ clip->x1 = min_t(u32, clip->x1, x);
+ clip->y1 = min_t(u32, clip->y1, y);
+ clip->x2 = max_t(u32, clip->x2, x + width);
+ clip->y2 = max_t(u32, clip->y2, y + height);
+ spin_unlock_irqrestore(&helper->dirty_lock, flags);
+
+ schedule_work(&helper->dirty_work);
+}
+
+/**
+ * drm_fb_helper_deferred_io() - fbdev deferred_io callback function
+ * @info: fb_info struct pointer
+ * @pagelist: list of dirty mmap framebuffer pages
+ *
+ * This function is used as the &fb_deferred_io ->deferred_io
+ * callback function for flushing the fbdev mmap writes.
+ */
+void drm_fb_helper_deferred_io(struct fb_info *info,
+ struct list_head *pagelist)
+{
+ unsigned long start, end, min, max;
+ struct page *page;
+ u32 y1, y2;
+
+ min = ULONG_MAX;
+ max = 0;
+ list_for_each_entry(page, pagelist, lru) {
+ start = page->index << PAGE_SHIFT;
+ end = start + PAGE_SIZE - 1;
+ min = min(min, start);
+ max = max(max, end);
+ }
+
+ if (min < max) {
+ y1 = min / info->fix.line_length;
+ y2 = min_t(u32, DIV_ROUND_UP(max, info->fix.line_length),
+ info->var.yres);
+ drm_fb_helper_dirty(info, 0, y1, info->var.xres, y2 - y1);
+ }
+}
+EXPORT_SYMBOL(drm_fb_helper_deferred_io);
+
/**
* drm_fb_helper_sys_read - wrapper around fb_sys_read
* @info: fb_info struct pointer
@@ -862,7 +944,14 @@
ssize_t drm_fb_helper_sys_write(struct fb_info *info, const char __user *buf,
size_t count, loff_t *ppos)
{
- return fb_sys_write(info, buf, count, ppos);
+ ssize_t ret;
+
+ ret = fb_sys_write(info, buf, count, ppos);
+ if (ret > 0)
+ drm_fb_helper_dirty(info, 0, 0, info->var.xres,
+ info->var.yres);
+
+ return ret;
}
EXPORT_SYMBOL(drm_fb_helper_sys_write);
@@ -877,6 +966,8 @@
const struct fb_fillrect *rect)
{
sys_fillrect(info, rect);
+ drm_fb_helper_dirty(info, rect->dx, rect->dy,
+ rect->width, rect->height);
}
EXPORT_SYMBOL(drm_fb_helper_sys_fillrect);
@@ -891,6 +982,8 @@
const struct fb_copyarea *area)
{
sys_copyarea(info, area);
+ drm_fb_helper_dirty(info, area->dx, area->dy,
+ area->width, area->height);
}
EXPORT_SYMBOL(drm_fb_helper_sys_copyarea);
@@ -905,6 +998,8 @@
const struct fb_image *image)
{
sys_imageblit(info, image);
+ drm_fb_helper_dirty(info, image->dx, image->dy,
+ image->width, image->height);
}
EXPORT_SYMBOL(drm_fb_helper_sys_imageblit);
@@ -919,6 +1014,8 @@
const struct fb_fillrect *rect)
{
cfb_fillrect(info, rect);
+ drm_fb_helper_dirty(info, rect->dx, rect->dy,
+ rect->width, rect->height);
}
EXPORT_SYMBOL(drm_fb_helper_cfb_fillrect);
@@ -933,6 +1030,8 @@
const struct fb_copyarea *area)
{
cfb_copyarea(info, area);
+ drm_fb_helper_dirty(info, area->dx, area->dy,
+ area->width, area->height);
}
EXPORT_SYMBOL(drm_fb_helper_cfb_copyarea);
@@ -947,6 +1046,8 @@
const struct fb_image *image)
{
cfb_imageblit(info, image);
+ drm_fb_helper_dirty(info, image->dx, image->dy,
+ image->width, image->height);
}
EXPORT_SYMBOL(drm_fb_helper_cfb_imageblit);