[Intel-gfx] [PATCH] drm/i915: Report the true swizzling modes to userspace via GET_PARAM

[Chris Wilson]

As we lie through the get_tiling ioctl about the swizzle mode, the
information that provides is unreliable and userspace has no way of
knowing the status of bit17 swizzling in the system. This prevents
userspace from using manual swizzling through a CPU map, which in
some circumstances is the optimal way of transferring data. Fix this
oversight, by providing a couple of PARAMs for userspace to query the
swizzle modes.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_dma.c | 6 ++++++
 include/uapi/drm/i915_drm.h     | 2 ++
 2 files changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index 893c9d1..c83c75d 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -1004,6 +1004,12 @@ static int i915_getparam(struct drm_device *dev, void *data,
 	case I915_PARAM_HAS_EXEC_HANDLE_LUT:
 		value = 1;
 		break;
+	case I915_PARAM_SWIZZLE_MODE_X:
+		value = dev_priv->mm.bit_6_swizzle_x;
+		break;
+	case I915_PARAM_SWIZZLE_MODE_Y:
+		value = dev_priv->mm.bit_6_swizzle_y;
+		break;
 	default:
 		DRM_DEBUG("Unknown parameter %d\n", param->param);
 		return -EINVAL;
diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
index b1dcf05..c5ba08b 100644
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -317,6 +317,8 @@ typedef struct drm_i915_irq_wait {
 #define I915_PARAM_HAS_EXEC_NO_RELOC	 25
 #define I915_PARAM_HAS_EXEC_HANDLE_LUT   26
 #define I915_PARAM_HAS_GFDT		 27
+#define I915_PARAM_SWIZZLE_MODE_X	 28
+#define I915_PARAM_SWIZZLE_MODE_Y	 29
 
 typedef struct drm_i915_getparam {
 	int param;
-- 
1.8.3.1