From: Rebecca Schultz <rschultz@xxxxxxxxxx>
Rather than signaling a full update of the display from userspace via aconsole switch, this patch introduces 2 files int /sys/power,wait_for_fb_sleep and wait_for_fb_wake. Reading these files will blockuntil the requested state has been entered. When a read fromwait_for_fb_sleep returns userspace should stop drawing. Whenwait_for_fb_wake returns, it should do a full update. If either are calledwhen the fb driver is already in the requested state, they will returnimmediately.
Signed-off-by: Rebecca Schultz <rschultz@xxxxxxxxxx>Signed-off-by: Arve Hjønnevåg <arve@xxxxxxxxxxx>--- kernel/power/Kconfig | 9 +++ kernel/power/Makefile | 1 + kernel/power/fbearlysuspend.c | 153 +++++++++++++++++++++++++++++++++++++++++ 3 files changed, 163 insertions(+), 0 deletions(-) create mode 100644 kernel/power/fbearlysuspend.c
diff --git a/kernel/power/Kconfig b/kernel/power/Kconfigindex 04e6fad..a214ef2 100644--- a/kernel/power/Kconfig+++ b/kernel/power/Kconfig@@ -161,6 +161,7 @@ config EARLYSUSPEND choice prompt "User-space screen access"+ default FB_EARLYSUSPEND if !FRAMEBUFFER_CONSOLE default CONSOLE_EARLYSUSPEND depends on EARLYSUSPEND @@ -174,6 +175,14 @@ choice Register early suspend handler to perform a console switch when user-space should stop drawing to the screen and a switch back when it should resume.++ config FB_EARLYSUSPEND+ bool "Sysfs interface"+ depends on EARLYSUSPEND+ ---help---+ Register early suspend handler that notifies and waits for+ user-space through sysfs when user-space should stop drawing+ to the screen and notifies user-space when it should resume. endchoice config HIBERNATIONdiff --git a/kernel/power/Makefile b/kernel/power/Makefileindex 8bf293d..5beaa21 100644--- a/kernel/power/Makefile+++ b/kernel/power/Makefile@@ -10,6 +10,7 @@ obj-$(CONFIG_WAKELOCK) += wakelock.o obj-$(CONFIG_USER_WAKELOCK) += userwakelock.o obj-$(CONFIG_EARLYSUSPEND) += earlysuspend.o obj-$(CONFIG_CONSOLE_EARLYSUSPEND) += consoleearlysuspend.o+obj-$(CONFIG_FB_EARLYSUSPEND) += fbearlysuspend.o obj-$(CONFIG_HIBERNATION) += swsusp.o disk.o snapshot.o swap.o user.o obj-$(CONFIG_MAGIC_SYSRQ) += poweroff.odiff --git a/kernel/power/fbearlysuspend.c b/kernel/power/fbearlysuspend.cnew file mode 100644index 0000000..19f3e54--- /dev/null+++ b/kernel/power/fbearlysuspend.c@@ -0,0 +1,153 @@+/* kernel/power/fbearlysuspend.c+ *+ * Copyright (C) 2005-2008 Google, Inc.+ *+ * This software is licensed under the terms of the GNU General Public+ * License version 2, as published by the Free Software Foundation, and+ * may be copied, distributed, and modified under those terms.+ *+ * This program is distributed in the hope that it will be useful,+ * but WITHOUT ANY WARRANTY; without even the implied warranty of+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the+ * GNU General Public License for more details.+ *+ */++#include <linux/earlysuspend.h>+#include <linux/module.h>+#include <linux/wait.h>++#include "power.h"++static wait_queue_head_t fb_state_wq;+static DEFINE_SPINLOCK(fb_state_lock);+static enum {+ FB_STATE_STOPPED_DRAWING,+ FB_STATE_REQUEST_STOP_DRAWING,+ FB_STATE_DRAWING_OK,+} fb_state;++/* tell userspace to stop drawing, wait for it to stop */+static void stop_drawing_early_suspend(struct early_suspend *h)+{+ int ret;+ unsigned long irq_flags;++ spin_lock_irqsave(&fb_state_lock, irq_flags);+ fb_state = FB_STATE_REQUEST_STOP_DRAWING;+ spin_unlock_irqrestore(&fb_state_lock, irq_flags);++ wake_up_all(&fb_state_wq);+ ret = wait_event_timeout(fb_state_wq,+ fb_state == FB_STATE_STOPPED_DRAWING,+ HZ);+ if (unlikely(fb_state != FB_STATE_STOPPED_DRAWING))+ pr_warning("stop_drawing_early_suspend: timeout waiting for "+ "userspace to stop drawing\n");+}++/* tell userspace to start drawing */+static void start_drawing_late_resume(struct early_suspend *h)+{+ unsigned long irq_flags;++ spin_lock_irqsave(&fb_state_lock, irq_flags);+ fb_state = FB_STATE_DRAWING_OK;+ spin_unlock_irqrestore(&fb_state_lock, irq_flags);+ wake_up(&fb_state_wq);+}++static struct early_suspend stop_drawing_early_suspend_desc = {+ .level = EARLY_SUSPEND_LEVEL_STOP_DRAWING,+ .suspend = stop_drawing_early_suspend,+ .resume = start_drawing_late_resume,+};++static ssize_t wait_for_fb_sleep_show(struct kobject *kobj,+ struct kobj_attribute *attr, char *buf)+{+ char *s = buf;+ int ret;++ ret = wait_event_interruptible(fb_state_wq,+ fb_state != FB_STATE_DRAWING_OK);+ if (ret && fb_state == FB_STATE_DRAWING_OK)+ return ret;+ else+ s += sprintf(buf, "sleeping");+ return s - buf;+}++static ssize_t wait_for_fb_wake_show(struct kobject *kobj,+ struct kobj_attribute *attr, char *buf)+{+ char *s = buf;+ int ret;+ unsigned long irq_flags;++ spin_lock_irqsave(&fb_state_lock, irq_flags);+ if (fb_state == FB_STATE_REQUEST_STOP_DRAWING) {+ fb_state = FB_STATE_STOPPED_DRAWING;+ wake_up(&fb_state_wq);+ }+ spin_unlock_irqrestore(&fb_state_lock, irq_flags);++ ret = wait_event_interruptible(fb_state_wq,+ fb_state == FB_STATE_DRAWING_OK);+ if (ret && fb_state != FB_STATE_DRAWING_OK)+ return ret;+ else+ s += sprintf(buf, "awake");++ return s - buf;+}++#define power_ro_attr(_name) \+static struct kobj_attribute _name##_attr = { \+ .attr = { \+ .name = __stringify(_name), \+ .mode = 0444, \+ }, \+ .show = _name##_show, \+ .store = NULL, \+}++power_ro_attr(wait_for_fb_sleep);+power_ro_attr(wait_for_fb_wake);++static struct attribute *g[] = {+ &wait_for_fb_sleep_attr.attr,+ &wait_for_fb_wake_attr.attr,+ NULL,+};++static struct attribute_group attr_group = {+ .attrs = g,+};++static int __init fb_earlysuspend_init(void)+{+ int ret;++ init_waitqueue_head(&fb_state_wq);+ fb_state = FB_STATE_DRAWING_OK;++ ret = sysfs_create_group(power_kobj, &attr_group);+ if (ret) {+ pr_err("fb_earlysuspend_init: sysfs_create_group failed\n");+ return ret;+ }++ register_early_suspend(&stop_drawing_early_suspend_desc);+ return 0;+}++static void __exit fb_earlysuspend_exit(void)+{+ unregister_early_suspend(&stop_drawing_early_suspend_desc);+ sysfs_remove_group(power_kobj, &attr_group);+}++module_init(fb_earlysuspend_init);+module_exit(fb_earlysuspend_exit);+-- 1.6.1
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