[RFC/PATCH] drm: Fix for non-coherent DMA PowerPC

[Benjamin Herrenschmidt]

This patch fixes bits of the DRM so to make the radeon DRI work on
non-cache coherent PCI DMA variants of the PowerPC processors.

It moves the few places that needs change to wrappers to that
other architectures with similar issues can easily add their
own changes to those wrappers, at least until we have more useful
generic kernel API.

Signed-off-by: Benjamin Herrenschmidt <benh at kernel.crashing.org>
---

 drivers/char/drm/ati_pcigart.c |    6 ++++++
 drivers/char/drm/drm_scatter.c |   12 +++++++++++-
 drivers/char/drm/drm_vm.c      |   20 +++++++++++++++-----
 3 files changed, 32 insertions(+), 6 deletions(-)

Index: linux-work/drivers/char/drm/ati_pcigart.c
===================================================================
--- linux-work.orig/drivers/char/drm/ati_pcigart.c	2007-11-26 10:07:29.000000000 +1100
+++ linux-work/drivers/char/drm/ati_pcigart.c	2007-11-26 10:21:33.000000000 +1100
@@ -214,6 +214,12 @@ int drm_ati_pcigart_init(struct drm_devi
 		}
 	}
 
+	if (gart_info->gart_table_location == DRM_ATI_GART_MAIN)
+		dma_sync_single_for_device(&dev->pdev->dev,
+					   bus_address,
+					   max_pages * sizeof(u32),
+					   PCI_DMA_TODEVICE);
+
 	ret = 1;
 
 #if defined(__i386__) || defined(__x86_64__)
Index: linux-work/drivers/char/drm/drm_scatter.c
===================================================================
--- linux-work.orig/drivers/char/drm/drm_scatter.c	2007-11-26 10:07:29.000000000 +1100
+++ linux-work/drivers/char/drm/drm_scatter.c	2007-11-26 10:20:08.000000000 +1100
@@ -36,6 +36,16 @@
 
 #define DEBUG_SCATTER 0
 
+static inline void *drm_vmalloc_dma(unsigned long size)
+{
+#if defined(__powerpc__) && defined(CONFIG_NOT_COHERENT_CACHE)
+	return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM,
+			 PAGE_KERNEL | _PAGE_NO_CACHE);
+#else
+	return vmalloc_32(size);
+#endif
+}
+
 void drm_sg_cleanup(struct drm_sg_mem * entry)
 {
 	struct page *page;
@@ -104,7 +114,7 @@ int drm_sg_alloc(struct drm_device *dev,
 	}
 	memset((void *)entry->busaddr, 0, pages * sizeof(*entry->busaddr));
 
-	entry->virtual = vmalloc_32(pages << PAGE_SHIFT);
+	entry->virtual = drm_vmalloc_dma(pages << PAGE_SHIFT);
 	if (!entry->virtual) {
 		drm_free(entry->busaddr,
 			 entry->pages * sizeof(*entry->busaddr), DRM_MEM_PAGES);
Index: linux-work/drivers/char/drm/drm_vm.c
===================================================================
--- linux-work.orig/drivers/char/drm/drm_vm.c	2007-11-26 10:07:29.000000000 +1100
+++ linux-work/drivers/char/drm/drm_vm.c	2007-11-26 10:11:09.000000000 +1100
@@ -54,13 +54,24 @@ static pgprot_t drm_io_prot(uint32_t map
 	pgprot_val(tmp) |= _PAGE_NO_CACHE;
 	if (map_type == _DRM_REGISTERS)
 		pgprot_val(tmp) |= _PAGE_GUARDED;
-#endif
-#if defined(__ia64__)
+#elif defined(__ia64__)
 	if (efi_range_is_wc(vma->vm_start, vma->vm_end -
 				    vma->vm_start))
 		tmp = pgprot_writecombine(tmp);
 	else
 		tmp = pgprot_noncached(tmp);
+#elif defined(__sparc__)
+	tmp = pgprot_noncached(tmp);
+#endif
+	return tmp;
+}
+
+static pgprot_t drm_dma_prot(uint32_t map_type, struct vm_area_struct *vma)
+{
+	pgprot_t tmp = vm_get_page_prot(vma->vm_flags);
+
+#if defined(__powerpc__) && defined(CONFIG_NOT_COHERENT_CACHE)
+	tmp |= _PAGE_NO_CACHE;
 #endif
 	return tmp;
 }
@@ -617,9 +628,6 @@ static int drm_mmap_locked(struct file *
 		offset = dev->driver->get_reg_ofs(dev);
 		vma->vm_flags |= VM_IO;	/* not in core dump */
 		vma->vm_page_prot = drm_io_prot(map->type, vma);
-#ifdef __sparc__
-		vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
-#endif
 		if (io_remap_pfn_range(vma, vma->vm_start,
 				       (map->offset + offset) >> PAGE_SHIFT,
 				       vma->vm_end - vma->vm_start,
@@ -638,6 +646,7 @@ static int drm_mmap_locked(struct file *
 		    page_to_pfn(virt_to_page(map->handle)),
 		    vma->vm_end - vma->vm_start, vma->vm_page_prot))
 			return -EAGAIN;
+		vma->vm_page_prot = drm_dma_prot(map->type, vma);
 	/* fall through to _DRM_SHM */
 	case _DRM_SHM:
 		vma->vm_ops = &drm_vm_shm_ops;
@@ -650,6 +659,7 @@ static int drm_mmap_locked(struct file *
 		vma->vm_ops = &drm_vm_sg_ops;
 		vma->vm_private_data = (void *)map;
 		vma->vm_flags |= VM_RESERVED;
+		vma->vm_page_prot = drm_dma_prot(map->type, vma);
 		break;
 	default:
 		return -EINVAL;	/* This should never happen. */