drm/msm: add support for "stolen" mem
Add support to use the VRAM carveout (if specified in dtb) for fbdev
scanout buffer. This allows drm/msm to take over a bootloader splash-
screen, and avoids corruption on screen that results if the kernel uses
memory that is still being scanned out for itself.
Signed-off-by: Rob Clark <robdclark@gmail.com>
diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
index b250610..0c38f34 100644
--- a/drivers/gpu/drm/msm/msm_drv.c
+++ b/drivers/gpu/drm/msm/msm_drv.c
@@ -182,21 +182,57 @@
return 4;
}
+#include <linux/of_address.h>
+
static int msm_init_vram(struct drm_device *dev)
{
struct msm_drm_private *priv = dev->dev_private;
+ unsigned long size = 0;
+ int ret = 0;
+
+#ifdef CONFIG_OF
+ /* In the device-tree world, we could have a 'memory-region'
+ * phandle, which gives us a link to our "vram". Allocating
+ * is all nicely abstracted behind the dma api, but we need
+ * to know the entire size to allocate it all in one go. There
+ * are two cases:
+ * 1) device with no IOMMU, in which case we need exclusive
+ * access to a VRAM carveout big enough for all gpu
+ * buffers
+ * 2) device with IOMMU, but where the bootloader puts up
+ * a splash screen. In this case, the VRAM carveout
+ * need only be large enough for fbdev fb. But we need
+ * exclusive access to the buffer to avoid the kernel
+ * using those pages for other purposes (which appears
+ * as corruption on screen before we have a chance to
+ * load and do initial modeset)
+ */
+ struct device_node *node;
+
+ node = of_parse_phandle(dev->dev->of_node, "memory-region", 0);
+ if (node) {
+ struct resource r;
+ ret = of_address_to_resource(node, 0, &r);
+ if (ret)
+ return ret;
+ size = r.end - r.start;
+ DRM_INFO("using VRAM carveout: %lx@%08x\n", size, r.start);
+ } else
+#endif
/* if we have no IOMMU, then we need to use carveout allocator.
* Grab the entire CMA chunk carved out in early startup in
* mach-msm:
*/
if (!iommu_present(&platform_bus_type)) {
+ DRM_INFO("using %s VRAM carveout\n", vram);
+ size = memparse(vram, NULL);
+ }
+
+ if (size) {
DEFINE_DMA_ATTRS(attrs);
- unsigned long size;
void *p;
- DBG("using %s VRAM carveout", vram);
- size = memparse(vram, NULL);
priv->vram.size = size;
drm_mm_init(&priv->vram.mm, 0, (size >> PAGE_SHIFT) - 1);
@@ -220,7 +256,7 @@
(uint32_t)(priv->vram.paddr + size));
}
- return 0;
+ return ret;
}
static int msm_load(struct drm_device *dev, unsigned long flags)