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Commit eaa434de authored by Noralf Trønnes's avatar Noralf Trønnes Committed by Daniel Vetter
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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 bcb39af4
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: default avatarNoralf Trønnes <noralf@tronnes.org>
Reviewed-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
[danvet: Augment commit message with why we need to handle atomic
contexts.]
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1461856717-6476-4-git-send-email-noralf@tronnes.org
parent 2b5e8e57

drivers/gpu/drm/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -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.

drivers/gpu/drm/drm_fb_helper.c

+102 −1
Original line number Diff line number Diff line
@@ -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);

include/drm/drm_fb_helper.h

+15 −0
Original line number Diff line number Diff line
@@ -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)