gpu/drm: remove the powerpc hack in drm_legacy_sg_alloc

The non-cached vmalloc mapping was initially added as a hack for the
first-gen amigaone platform (6xx/book32s), isn't fully supported upstream,
and which used the legacy radeon driver together with non-coherent DMA.
However this only ever worked reliably for DRI .

Remove the hack as it is the last user of __vmalloc passing a page
protection flag other than PAGE_KERNEL and didn't do anything for other
platforms with non-coherent DMA.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: David Airlie <airlied@linux.ie>
Cc: Gao Xiang <xiang@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michael Kelley <mikelley@microsoft.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Sakari Ailus <sakari.ailus@linux.intel.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Wei Liu <wei.liu@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Paul Mackerras <paulus@ozlabs.org>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will@kernel.org>
Link: http://lkml.kernel.org/r/20200414131348.444715-21-hch@lst.deSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/gpu/drm/drm_scatter.c

@@ -43,15 +43,6 @@
 
 #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, pgprot_noncached_wc(PAGE_KERNEL));
-#else
-	return vmalloc_32(size);
-#endif
-}
-
 static void drm_sg_cleanup(struct drm_sg_mem * entry)
 {
 	struct page *page;
@@ -126,7 +117,7 @@ int drm_legacy_sg_alloc(struct drm_device *dev, void *data,
 		return -ENOMEM;
 	}
 
-	entry->virtual = drm_vmalloc_dma(pages << PAGE_SHIFT);
+	entry->virtual = vmalloc_32(pages << PAGE_SHIFT);
 	if (!entry->virtual) {
 		kfree(entry->busaddr);
 		kfree(entry->pagelist);