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>

1 files changed, 20 insertions, 5 deletions

diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c
index 49dea4fb55ac..479d8af72bcb 100644
--- a/drivers/gpu/drm/msm/msm_gem.c
+++ b/drivers/gpu/drm/msm/msm_gem.c
@@ -32,6 +32,12 @@ static dma_addr_t physaddr(struct drm_gem_object *obj)
                         priv->vram.paddr;
 }
 
+static bool use_pages(struct drm_gem_object *obj)
+{
+        struct msm_gem_object *msm_obj = to_msm_bo(obj);
+        return !msm_obj->vram_node;
+}
+
 /* allocate pages from VRAM carveout, used when no IOMMU: */
 static struct page **get_pages_vram(struct drm_gem_object *obj,
                 int npages)
@@ -72,7 +78,7 @@ static struct page **get_pages(struct drm_gem_object *obj)
                 struct page **p;
                 int npages = obj->size >> PAGE_SHIFT;
 
-                if (iommu_present(&platform_bus_type))
+                if (use_pages(obj))
                         p = drm_gem_get_pages(obj);
                 else
                         p = get_pages_vram(obj, npages);
@@ -116,7 +122,7 @@ static void put_pages(struct drm_gem_object *obj)
                 sg_free_table(msm_obj->sgt);
                 kfree(msm_obj->sgt);
 
-                if (iommu_present(&platform_bus_type))
+                if (use_pages(obj))
                         drm_gem_put_pages(obj, msm_obj->pages, true, false);
                 else {
                         drm_mm_remove_node(msm_obj->vram_node);
@@ -580,6 +586,7 @@ static int msm_gem_new_impl(struct drm_device *dev,
         struct msm_drm_private *priv = dev->dev_private;
         struct msm_gem_object *msm_obj;
         unsigned sz;
+        bool use_vram = false;
 
         switch (flags & MSM_BO_CACHE_MASK) {
         case MSM_BO_UNCACHED:
@@ -592,15 +599,23 @@ static int msm_gem_new_impl(struct drm_device *dev,
                 return -EINVAL;
         }
 
-        sz = sizeof(*msm_obj);
         if (!iommu_present(&platform_bus_type))
+                use_vram = true;
+        else if ((flags & MSM_BO_STOLEN) && priv->vram.size)
+                use_vram = true;
+
+        if (WARN_ON(use_vram && !priv->vram.size))
+                return -EINVAL;
+
+        sz = sizeof(*msm_obj);
+        if (use_vram)
                 sz += sizeof(struct drm_mm_node);
 
         msm_obj = kzalloc(sz, GFP_KERNEL);
         if (!msm_obj)
                 return -ENOMEM;
 
-        if (!iommu_present(&platform_bus_type))
+        if (use_vram)
                 msm_obj->vram_node = (void *)&msm_obj[1];
 
         msm_obj->flags = flags;
@@ -630,7 +645,7 @@ struct drm_gem_object *msm_gem_new(struct drm_device *dev,
         if (ret)
                 goto fail;
 
-        if (iommu_present(&platform_bus_type)) {
+        if (use_pages(obj)) {
                 ret = drm_gem_object_init(dev, obj, size);
                 if (ret)
                         goto fail;