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 (file)
--- a/drivers/gpu/drm/msm/msm_drv.c
+++ b/drivers/gpu/drm/msm/msm_drv.c
@@ -182,21 +182,57 @@ static int get_mdp_ver(struct platform_device *pdev)
        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 @@ static int msm_init_vram(struct drm_device *dev)
                                (uint32_t)(priv->vram.paddr + size));
        }
 
-       return 0;
+       return ret;
 }
 
 static int msm_load(struct drm_device *dev, unsigned long flags)

diff --git a/drivers/gpu/drm/msm/msm_fbdev.c b/drivers/gpu/drm/msm/msm_fbdev.c
index df60f65..95f6532 100644 (file)
--- a/drivers/gpu/drm/msm/msm_fbdev.c
+++ b/drivers/gpu/drm/msm/msm_fbdev.c
@@ -110,7 +110,8 @@ static int msm_fbdev_create(struct drm_fb_helper *helper,
        size = mode_cmd.pitches[0] * mode_cmd.height;
        DBG("allocating %d bytes for fb %d", size, dev->primary->index);
        mutex_lock(&dev->struct_mutex);
-       fbdev->bo = msm_gem_new(dev, size, MSM_BO_SCANOUT | MSM_BO_WC);
+       fbdev->bo = msm_gem_new(dev, size, MSM_BO_SCANOUT |
+                       MSM_BO_WC | MSM_BO_STOLEN);
        mutex_unlock(&dev->struct_mutex);
        if (IS_ERR(fbdev->bo)) {
                ret = PTR_ERR(fbdev->bo);

diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c
index 49dea4f..479d8af 100644 (file)
--- 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;

diff --git a/drivers/gpu/drm/msm/msm_gem.h b/drivers/gpu/drm/msm/msm_gem.h
index 8fbbd05..85d481e 100644 (file)
--- a/drivers/gpu/drm/msm/msm_gem.h
+++ b/drivers/gpu/drm/msm/msm_gem.h
@@ -21,6 +21,9 @@
 #include <linux/reservation.h>
 #include "msm_drv.h"
 
+/* Additional internal-use only BO flags: */
+#define MSM_BO_STOLEN        0x10000000    /* try to use stolen/splash memory */
+
 struct msm_gem_object {
        struct drm_gem_object base;
 
@@ -59,7 +62,7 @@ struct msm_gem_object {
        struct reservation_object _resv;
 
        /* For physically contiguous buffers.  Used when we don't have
-        * an IOMMU.
+        * an IOMMU.  Also used for stolen/splashscreen buffer.
         */
        struct drm_mm_node *vram_node;
 };