[PATCH 1/4] xen-fbfront: Read width/height from backend

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

From: Daniel De Graaf <dgdegra@tycho.nsa.gov>

This allows the backend driver to specify the size of the framebuffer
instead of requiring it to be on the kernel command line.

Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: Ian Campbell <Ian.Campbell@eu.citrix.com>
---
 drivers/video/xen-fbfront.c |   30 ++++++++++++++++++++++++------
 1 files changed, 24 insertions(+), 6 deletions(-)

diff --git a/drivers/video/xen-fbfront.c b/drivers/video/xen-fbfront.c
index a20218c..56d6061 100644
--- a/drivers/video/xen-fbfront.c
+++ b/drivers/video/xen-fbfront.c
@@ -58,7 +58,7 @@ struct xenfb_info {
 #define XENFB_DEFAULT_FB_LEN (XENFB_WIDTH * XENFB_HEIGHT * XENFB_DEPTH / 8)
 
 enum { KPARAM_MEM, KPARAM_WIDTH, KPARAM_HEIGHT, KPARAM_CNT };
-static int video[KPARAM_CNT] = { 2, XENFB_WIDTH, XENFB_HEIGHT };
+static int video[KPARAM_CNT] = { 0, 0, 0 };
 module_param_array(video, int, NULL, 0);
 MODULE_PARM_DESC(video,
 	"Video memory size in MB, width, height in pixels (default 2,800,600)");
@@ -363,7 +363,7 @@ static int __devinit xenfb_probe(struct xenbus_device *dev,
 {
 	struct xenfb_info *info;
 	struct fb_info *fb_info;
-	int fb_size;
+	int fb_size, fb_need;
 	int val;
 	int ret;
 
@@ -375,14 +375,32 @@ static int __devinit xenfb_probe(struct xenbus_device *dev,
 
 	/* Limit kernel param videoram amount to what is in xenstore */
 	if (xenbus_scanf(XBT_NIL, dev->otherend, "videoram", "%d", &val) == 1) {
-		if (val < video[KPARAM_MEM])
+		if (!video[KPARAM_MEM] || val < video[KPARAM_MEM])
 			video[KPARAM_MEM] = val;
 	}
 
+	/* Take width/height from xenstore if not set on command line */
+	if (!video[KPARAM_WIDTH]) {
+		if (xenbus_scanf(XBT_NIL, dev->otherend, "width", "%d", &val) == 1)
+			video[KPARAM_WIDTH] = val;
+		else
+			video[KPARAM_WIDTH] = XENFB_WIDTH;
+	}
+	if (!video[KPARAM_HEIGHT]) {
+		if (xenbus_scanf(XBT_NIL, dev->otherend, "height", "%d", &val) == 1)
+			video[KPARAM_HEIGHT] = val;
+		else
+			video[KPARAM_HEIGHT] = XENFB_HEIGHT;
+	}
+
+	fb_need = video[KPARAM_WIDTH] * video[KPARAM_HEIGHT] * XENFB_DEPTH / 8;
+	if (video[KPARAM_MEM])
+		fb_size = video[KPARAM_MEM] * 1024 * 1024;
+	else
+		fb_size = video[KPARAM_MEM] = fb_need;
+
 	/* If requested res does not fit in available memory, use default */
-	fb_size = video[KPARAM_MEM] * 1024 * 1024;
-	if (video[KPARAM_WIDTH] * video[KPARAM_HEIGHT] * XENFB_DEPTH / 8
-	    > fb_size) {
+	if (fb_need > fb_size) {
 		video[KPARAM_WIDTH] = XENFB_WIDTH;
 		video[KPARAM_HEIGHT] = XENFB_HEIGHT;
 		fb_size = XENFB_DEFAULT_FB_LEN;
-- 
1.7.1