s3cfb: Notify userspace of vsync using sysfs, make uevents optional

Change-Id: I6fe8de47961d5c0ba73eb45543a675b6fd4344a4

2 files changed, 41 insertions, 0 deletions

diff --git a/drivers/video/samsung/Kconfig b/drivers/video/samsung/Kconfig
index 09711d3..0234465 100644
--- a/drivers/video/samsung/Kconfig
+++ b/drivers/video/samsung/Kconfig
@@ -38,6 +38,24 @@ config FB_S5P_VSYNC_THREAD
 	bool "S5P Framebuffer vsync thread"
 	depends on FB_S5P
 
+config FB_S5P_VSYNC_SEND_UEVENTS
+	bool "S5P Framebuffer vsync uevents"
+	depends on FB_S5P_VSYNC_THREAD
+	default n
+	help
+	  Some hwcomposer implementations support vsync hinting via uevents to userspace
+	  However this also wakes up many other parts of Android, draining battery.
+	  ICS hwcomposer does not support any form of sync, so these uevents should be
+	  optional and only sent to HWC implementations that expect uevents to be sent
+
+config FB_S5P_VSYNC_SYSFS
+    bool "S5P Framebuffer vsync via sysfs"
+    depends on FB_S5P_VSYNC_THREAD
+    default n
+    help
+    A more efficient method of passing vsync to userspace that doesn't
+    broadcast uevents.
+
 config FB_S5P_TRACE_UNDERRUN
 	bool "S5P Framebuffer FIFO underrun trace"
 	depends on FB_S5P
diff --git a/drivers/video/samsung/s3cfb_main.c b/drivers/video/samsung/s3cfb_main.c
index a723306..fadea40 100644
--- a/drivers/video/samsung/s3cfb_main.c
+++ b/drivers/video/samsung/s3cfb_main.c
@@ -387,6 +387,18 @@ static ssize_t fimd_dump_show(struct device *dev,
 }
 static DEVICE_ATTR(fimd_dump, 0444, fimd_dump_show, NULL);
 
+#ifdef CONFIG_FB_S5P_VSYNC_SYSFS
+static ssize_t s3c_fb_vsync_time(struct device *dev,
+                struct device_attribute *attr, char *buf)
+{
+    struct s3cfb_global *fbdev = fbfimd->fbdev[0];
+
+    return snprintf(buf, PAGE_SIZE, "%llu", ktime_to_ns(fbdev->vsync_info.timestamp));
+}
+
+static DEVICE_ATTR(vsync_time, S_IRUGO, s3c_fb_vsync_time, NULL);
+#endif
+
 #if 0 /* def CONFIG_FB_S5P_MIPI_DSIM */
 void s3cfb_display_on_remote(void)
 {
@@ -430,6 +442,7 @@ static int s3cfb_wait_for_vsync_thread(void *data)
 						msecs_to_jiffies(VSYNC_TIMEOUT_MSEC));
 
 		if (ret > 0) {
+#if defined(CONFIG_FB_S5P_VSYNC_SEND_UEVENTS)
 			char *envp[2];
 			char buf[64];
 			snprintf(buf, sizeof(buf), "VSYNC=%llu",
@@ -438,6 +451,10 @@ static int s3cfb_wait_for_vsync_thread(void *data)
 			envp[1] = NULL;
 			kobject_uevent_env(&fbdev->dev->kobj, KOBJ_CHANGE,
 							envp);
+#endif
+#if defined(CONFIG_FB_S5P_VSYNC_SYSFS)
+            sysfs_notify(&fbdev->dev->kobj, NULL, "vsync_time");
+#endif
 		}
 	}
 
@@ -667,6 +684,12 @@ static int s3cfb_probe(struct platform_device *pdev)
 		if (ret < 0)
 			dev_err(fbdev[0]->dev, "failed to add sysfs entries\n");
 
+#ifdef CONFIG_FB_S5P_VSYNC_SYSFS
+        ret = device_create_file(fbdev[i]->dev, &dev_attr_vsync_time);
+        if (ret < 0)
+            dev_err(fbdev[0]->dev, "failed to add sysfs entries\n");
+#endif
+
 		ret = device_create_file(fbdev[i]->dev, &dev_attr_ielcd_dump);
 		if (ret < 0)
 			dev_err(fbdev[0]->dev, "failed to add sysfs entries\n");