[PATCH] Revert "Revert "drm/amdgpu: use the BAR if possible in amdgpu_device_vram_access v2""

[Kent Russell]

This reverts commit e71391880aa72709fac53f98d96a2d4e8875b9fa.

The RAS issue at the base of this problem appears to have been addressed

Signed-off-by: Kent Russell <kent.russell at amd.com>
Change-Id: I338a985e19cae8e103bd44b0f238314e9460d396
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 26 ++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
index caa38e7d502e..bf302c799832 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
@@ -255,6 +255,32 @@ void amdgpu_device_vram_access(struct amdgpu_device *adev, loff_t pos,
 	uint32_t hi = ~0;
 	uint64_t last;
 
+
+#ifdef CONFIG_64BIT
+	last = min(pos + size, adev->gmc.visible_vram_size);
+	if (last > pos) {
+		void __iomem *addr = adev->mman.aper_base_kaddr + pos;
+		size_t count = last - pos;
+
+		if (write) {
+			memcpy_toio(addr, buf, count);
+			mb();
+			amdgpu_asic_flush_hdp(adev, NULL);
+		} else {
+			amdgpu_asic_invalidate_hdp(adev, NULL);
+			mb();
+			memcpy_fromio(buf, addr, count);
+		}
+
+		if (count == size)
+			return;
+
+		pos += count;
+		buf += count / 4;
+		size -= count;
+	}
+#endif
+
 	spin_lock_irqsave(&adev->mmio_idx_lock, flags);
 	for (last = pos + size; pos < last; pos += 4) {
 		uint32_t tmp = pos >> 31;
-- 
2.17.1