hw/display/bcm2835_fb: Reset resolution, etc correctly

The bcm2835_fb's initial resolution and other parameters are set
via QOM properties. We should reset to those initial values on
device reset, which means we need to save the QOM property
values somewhere that they are not overwritten by guest
changes to the framebuffer configuration.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NRichard Henderson <richard.henderson@linaro.org>
Message-id: 20180814144436.679-5-peter.maydell@linaro.org

hw/display/bcm2835_fb.c

@@ -329,11 +329,7 @@ static void bcm2835_fb_reset(DeviceState *dev)
 
     s->pending = false;
 
-    s->config.xres_virtual = s->config.xres;
-    s->config.yres_virtual = s->config.yres;
-    s->config.xoffset = 0;
-    s->config.yoffset = 0;
-    s->config.base = s->vcram_base + BCM2835_FB_OFFSET;
+    s->config = s->initial_config;
 
     s->invalidate = true;
     s->lock = false;
@@ -357,6 +353,13 @@ static void bcm2835_fb_realize(DeviceState *dev, Error **errp)
         return;
     }
 
+    /* Fill in the parts of initial_config that are not set by QOM properties */
+    s->initial_config.xres_virtual = s->initial_config.xres;
+    s->initial_config.yres_virtual = s->initial_config.yres;
+    s->initial_config.xoffset = 0;
+    s->initial_config.yoffset = 0;
+    s->initial_config.base = s->vcram_base + BCM2835_FB_OFFSET;
+
     s->dma_mr = MEMORY_REGION(obj);
     address_space_init(&s->dma_as, s->dma_mr, NULL);
 
@@ -370,13 +373,13 @@ static Property bcm2835_fb_props[] = {
     DEFINE_PROP_UINT32("vcram-base", BCM2835FBState, vcram_base, 0),/*required*/
     DEFINE_PROP_UINT32("vcram-size", BCM2835FBState, vcram_size,
                        DEFAULT_VCRAM_SIZE),
-    DEFINE_PROP_UINT32("xres", BCM2835FBState, config.xres, 640),
-    DEFINE_PROP_UINT32("yres", BCM2835FBState, config.yres, 480),
-    DEFINE_PROP_UINT32("bpp", BCM2835FBState, config.bpp, 16),
-    DEFINE_PROP_UINT32("pixo",
-                       BCM2835FBState, config.pixo, 1), /* 1=RGB, 0=BGR */
-    DEFINE_PROP_UINT32("alpha",
-                       BCM2835FBState, config.alpha, 2), /* alpha ignored */
+    DEFINE_PROP_UINT32("xres", BCM2835FBState, initial_config.xres, 640),
+    DEFINE_PROP_UINT32("yres", BCM2835FBState, initial_config.yres, 480),
+    DEFINE_PROP_UINT32("bpp", BCM2835FBState, initial_config.bpp, 16),
+    DEFINE_PROP_UINT32("pixo", BCM2835FBState,
+                       initial_config.pixo, 1), /* 1=RGB, 0=BGR */
+    DEFINE_PROP_UINT32("alpha", BCM2835FBState,
+                       initial_config.alpha, 2), /* alpha ignored */
     DEFINE_PROP_END_OF_LIST()
 };
 

include/hw/display/bcm2835_fb.h

@@ -47,6 +47,7 @@ typedef struct {
     bool lock, invalidate, pending;
 
     BCM2835FBConfig config;
+    BCM2835FBConfig initial_config;
 } BCM2835FBState;
 
 void bcm2835_fb_reconfigure(BCM2835FBState *s, BCM2835FBConfig *newconfig);