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drm/fb-helper: Add fb_deferred_io support

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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 bcb39af448
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
This commit is contained in:
Noralf Trønnes 2016-04-28 17:18:33 +02:00 committed by Daniel Vetter
parent 2b5e8e579b
commit eaa434defa
3 changed files with 118 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
drivers/gpu/drm/Kconfig
View File

@ -52,6 +52,7 @@ config DRM_KMS_FB_HELPER
select FB_CFB_FILLRECT
select FB_CFB_COPYAREA
select FB_CFB_IMAGEBLIT
select FB_DEFERRED_IO
help
FBDEV helpers for KMS drivers.

103
drivers/gpu/drm/drm_fb_helper.c
View File

@ -84,6 +84,15 @@ static LIST_HEAD(kernel_fb_helper_list);
* 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 @@ static void drm_fb_helper_crtc_free(struct drm_fb_helper *helper)
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 @@ void drm_fb_helper_prepare(struct drm_device *dev, struct drm_fb_helper *helper,
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 @@ void drm_fb_helper_unlink_fbi(struct drm_fb_helper *fb_helper)
}
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 @@ EXPORT_SYMBOL(drm_fb_helper_sys_read);
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 @@ void drm_fb_helper_sys_fillrect(struct fb_info *info,
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 @@ void drm_fb_helper_sys_copyarea(struct fb_info *info,
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 @@ void drm_fb_helper_sys_imageblit(struct fb_info *info,
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 @@ void drm_fb_helper_cfb_fillrect(struct fb_info *info,
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 @@ void drm_fb_helper_cfb_copyarea(struct fb_info *info,
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 @@ void drm_fb_helper_cfb_imageblit(struct fb_info *info,
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);

15
include/drm/drm_fb_helper.h
View File

@ -172,6 +172,10 @@ struct drm_fb_helper_connector {
* @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 @@ struct drm_fb_helper {
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_fill_fix(struct fb_info *info, uint32_t pitch,
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_unlink_fbi(struct drm_fb_helper *fb_helper)
{
}
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)