[PATCH 2/2] drm/omap: add OMAP_BO flags to affect buffer allocation

[Tomi Valkeinen]

On SoCs with TILER, we have to ways to allocate buffers: normal
dma_alloc or via TILER (which basically functions as an IOMMU). TILER
can map 128MB at a time, and we only map the TILER buffers when they are
used (i.e. not at alloc time). If TILER is present, omapdrm always
uses TILER.

There are use cases that require lots of big buffers that are being used
at the same time by different IPs. At the moment the userspace has a
hard maximum of 128MB.

This patch adds three new flags that can be used by the userspace to
solve the situation:

OMAP_BO_MEM_CONTIG: The driver will use dma_alloc to get the memory.
This can be used to avoid TILER if the userspace knows it needs more
than 128M of memory at the same time.

OMAP_BO_MEM_TILER: The driver will use TILER to get the memory. There's
nto much use for this flag at the moment, but it's here for
completeness.

OMAP_BO_MEM_PIN: The driver will pin the memory at alloc time, and keep
it pinned. This can be used to 1) get an error at alloc time if TILER
space is full, and 2) get rid of the constant pin/unpin operations which
may have some effect on performance.

If none of the flags are given, the behavior is the same as currently.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen at ti.com>
---
 drivers/gpu/drm/omapdrm/omap_gem.c | 23 ++++++++++++++++++++++-
 include/uapi/drm/omap_drm.h        |  3 +++
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/omapdrm/omap_gem.c b/drivers/gpu/drm/omapdrm/omap_gem.c
index 5d73dccc1383..90ae8615f6c6 100644
--- a/drivers/gpu/drm/omapdrm/omap_gem.c
+++ b/drivers/gpu/drm/omapdrm/omap_gem.c
@@ -1292,6 +1292,9 @@ void omap_gem_free_object(struct drm_gem_object *obj)
 	list_del(&omap_obj->mm_list);
 	spin_unlock(&priv->list_lock);
 
+	if (omap_obj->flags & OMAP_BO_MEM_PIN)
+		omap_gem_put_paddr_locked(obj);
+
 	/* this means the object is still pinned.. which really should
 	 * not happen.  I think..
 	 */
@@ -1338,6 +1341,11 @@ struct drm_gem_object *omap_gem_new(struct drm_device *dev,
 			return NULL;
 		}
 
+		if (flags & OMAP_BO_MEM_CONTIG) {
+			dev_err(dev->dev, "Tiled buffers require TILER memory\n");
+			return NULL;
+		}
+
 		/*
 		 * Tiled buffers are always shmem paged backed. When they are
 		 * scanned out, they are remapped into DMM/TILER.
@@ -1351,7 +1359,8 @@ struct drm_gem_object *omap_gem_new(struct drm_device *dev,
 		 */
 		flags &= ~(OMAP_BO_CACHED|OMAP_BO_WC|OMAP_BO_UNCACHED);
 		flags |= tiler_get_cpu_cache_flags();
-	} else if ((flags & OMAP_BO_SCANOUT) && !priv->has_dmm) {
+	} else if ((flags & OMAP_BO_MEM_CONTIG) ||
+		((flags & OMAP_BO_SCANOUT) && !priv->has_dmm)) {
 		/*
 		 * OMAP_BO_SCANOUT hints that the buffer doesn't need to be
 		 * tiled. However, to lower the pressure on memory allocation,
@@ -1411,12 +1420,24 @@ struct drm_gem_object *omap_gem_new(struct drm_device *dev,
 			goto err_release;
 	}
 
+	if (flags & OMAP_BO_MEM_PIN) {
+		dma_addr_t dummy;
+
+		ret = omap_gem_get_paddr(obj, &dummy, true);
+		if (ret)
+			goto err_free_dma;
+	}
+
 	spin_lock(&priv->list_lock);
 	list_add(&omap_obj->mm_list, &priv->obj_list);
 	spin_unlock(&priv->list_lock);
 
 	return obj;
 
+err_free_dma:
+	if (flags & OMAP_BO_MEM_DMA_API)
+		dma_free_writecombine(dev->dev, size,
+				omap_obj->vaddr, omap_obj->paddr);
 err_release:
 	drm_gem_object_release(obj);
 err_free:
diff --git a/include/uapi/drm/omap_drm.h b/include/uapi/drm/omap_drm.h
index 7fb97863c945..a976e8682c5f 100644
--- a/include/uapi/drm/omap_drm.h
+++ b/include/uapi/drm/omap_drm.h
@@ -40,6 +40,9 @@ struct drm_omap_param {
 #define OMAP_BO_SCANOUT		0x00000001	/* scanout capable (phys contiguous) */
 #define OMAP_BO_CACHE_MASK	0x00000006	/* cache type mask, see cache modes */
 #define OMAP_BO_TILED_MASK	0x00000f00	/* tiled mapping mask, see tiled modes */
+#define OMAP_BO_MEM_CONTIG	0x00000008	/* only use contiguous dma mem */
+#define OMAP_BO_MEM_TILER	0x00000010	/* only use TILER mem */
+#define OMAP_BO_MEM_PIN		0x00000020	/* pin the buffer when allocating */
 
 /* cache modes */
 #define OMAP_BO_CACHED		0x00000000	/* default */
-- 
2.7.4