msm: mdss: change framebuffer split ratio at run time

This is to avoid kernel recompilation when a different
framebuffer split ratio is desired at run time. To
enable a new ratio, write the  desired value to
/sys/devices/virtual/graphics/fb0/msm_fb_split.
Changes will take effect only after client releases
all references to driver.

Change-Id: I4764399f80fc22ec5815a8e2818901189b3aaeb5
Signed-off-by: Jayant Shekhar <jshekhar@codeaurora.org>

2 files changed, 65 insertions, 21 deletions

diff --git a/drivers/video/fbdev/msm/mdss_fb.c b/drivers/video/fbdev/msm/mdss_fb.c
index cbf0d03bd794..b28ffdaa206a 100644
--- a/drivers/video/fbdev/msm/mdss_fb.c
+++ b/drivers/video/fbdev/msm/mdss_fb.c
@@ -309,10 +309,36 @@ static ssize_t mdss_fb_get_type(struct device *dev,
 	return ret;
 }
 
-static void mdss_fb_parse_dt(struct msm_fb_data_type *mfd)
+static inline int mdss_fb_validate_split(int left, int right,
+			struct msm_fb_data_type *mfd)
+{
+	int rc = -EINVAL;
+	u32 panel_xres = mfd->panel_info->xres;
+	/* more validate condition could be added if needed */
+	if (left && right) {
+		if (mfd->split_display)
+			panel_xres *= 2;
+
+		if (panel_xres == left + right) {
+			mfd->split_fb_left = left;
+			mfd->split_fb_right = right;
+			rc = 0;
+		}
+	} else {
+		if (mfd->split_display) {
+			mfd->split_fb_left = mfd->split_fb_right = panel_xres;
+			rc = 0;
+		} else {
+			mfd->split_fb_left = mfd->split_fb_right = 0;
+		}
+	}
+
+	return rc;
+}
+
+static void mdss_fb_parse_dt_split(struct msm_fb_data_type *mfd)
 {
 	u32 data[2] = {0};
-	u32 panel_xres;
 	struct platform_device *pdev = mfd->pdev;
 
 	mfd->splash_logo_enabled = of_property_read_bool(pdev->dev.of_node,
@@ -321,26 +347,29 @@ static void mdss_fb_parse_dt(struct msm_fb_data_type *mfd)
 	of_property_read_u32_array(pdev->dev.of_node,
 		"qcom,mdss-fb-split", data, 2);
 
-	panel_xres = mfd->panel_info->xres;
-	if (data[0] && data[1]) {
-		if (mfd->split_display)
-			panel_xres *= 2;
+	if (!mdss_fb_validate_split(data[0], data[1], mfd))
+		pr_debug("dt split_left=%d split_right=%d\n", data[0], data[1]);
+}
 
-		if (panel_xres == data[0] + data[1]) {
-			mfd->split_fb_left = data[0];
-			mfd->split_fb_right = data[1];
-		}
-	} else {
-		if (mfd->split_display)
-			mfd->split_fb_left = mfd->split_fb_right = panel_xres;
-		else
-			mfd->split_fb_left = mfd->split_fb_right = 0;
+static ssize_t mdss_fb_store_split(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t len)
+{
+	u32 data[2] = {0};
+	struct fb_info *fbi = dev_get_drvdata(dev);
+	struct msm_fb_data_type *mfd = (struct msm_fb_data_type *)fbi->par;
+
+	if (2 != sscanf(buf, "%d %d", &data[0], &data[1])) {
+		pr_debug("Not able to read split values\n");
+	} else if (!mdss_fb_validate_split(data[0], data[1], mfd)) {
+		mfd->mdss_fb_split_stored = 1;
+		pr_debug("sys split_left=%d split_right=%d\n",
+					data[0], data[1]);
 	}
-	pr_info("split framebuffer left=%d right=%d\n",
-		mfd->split_fb_left, mfd->split_fb_right);
+
+	return len;
 }
 
-static ssize_t mdss_fb_get_split(struct device *dev,
+static ssize_t mdss_fb_show_split(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	ssize_t ret = 0;
@@ -351,6 +380,19 @@ static ssize_t mdss_fb_get_split(struct device *dev,
 	return ret;
 }
 
+static void mdss_fb_get_split(struct msm_fb_data_type *mfd)
+{
+	if (mfd->index != 0)
+		return;
+
+	if (!mfd->mdss_fb_split_stored)
+		mdss_fb_parse_dt_split(mfd);
+
+	if (mfd->split_fb_left || mfd->split_fb_right)
+		pr_debug("split framebuffer left=%d right=%d\n",
+			mfd->split_fb_left, mfd->split_fb_right);
+}
+
 static ssize_t mdss_mdp_show_blank_event(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
@@ -441,7 +483,8 @@ static ssize_t mdss_fb_get_panel_info(struct device *dev,
 }
 
 static DEVICE_ATTR(msm_fb_type, S_IRUGO, mdss_fb_get_type, NULL);
-static DEVICE_ATTR(msm_fb_split, S_IRUGO, mdss_fb_get_split, NULL);
+static DEVICE_ATTR(msm_fb_split, S_IRUGO | S_IWUSR, mdss_fb_show_split,
+					mdss_fb_store_split);
 static DEVICE_ATTR(show_blank_event, S_IRUGO, mdss_mdp_show_blank_event, NULL);
 static DEVICE_ATTR(idle_time, S_IRUGO | S_IWUSR | S_IWGRP,
 	mdss_fb_get_idle_time, mdss_fb_set_idle_time);
@@ -1422,8 +1465,6 @@ static int mdss_fb_register(struct msm_fb_data_type *mfd)
 	mfd->panel_power_on = false;
 	mfd->dcm_state = DCM_UNINIT;
 
-	mdss_fb_parse_dt(mfd);
-
 	if (mdss_fb_alloc_fbmem(mfd))
 		pr_warn("unable to allocate fb memory in fb register\n");
 
@@ -1505,6 +1546,7 @@ static int mdss_fb_open(struct fb_info *info, int user)
 	}
 
 	if (!mfd->ref_cnt) {
+		mdss_fb_get_split(mfd);
 		mfd->disp_thread = kthread_run(__mdss_fb_display_thread, mfd,
 				"mdss_fb%d", mfd->index);
 		if (IS_ERR(mfd->disp_thread)) {
diff --git a/drivers/video/fbdev/msm/mdss_fb.h b/drivers/video/fbdev/msm/mdss_fb.h
index 66330b73d605..f291d5bc094e 100644
--- a/drivers/video/fbdev/msm/mdss_fb.h
+++ b/drivers/video/fbdev/msm/mdss_fb.h
@@ -234,6 +234,8 @@ struct msm_fb_data_type {
 	struct list_head proc_list;
 	struct ion_client *fb_ion_client;
 	struct ion_handle *fb_ion_handle;
+
+	bool mdss_fb_split_stored;
 };
 
 static inline void mdss_fb_update_notify_update(struct msm_fb_data_type *mfd)