drm/msm/mdp: Add Software Pixel Extension support

In order to produce an image, the scalar needs to be fed extra
pixels. These top/bottom/left/right values depend on a various of
factors, including resolution, scaling type, phase step and
initial phase.

Pixel Extension are programmed by hardware in most targets - and
can be overwritten by software. For some targets (e.g.: msm8996),
software *must* program those registers.

In order to ease this computation, let's always use bilinear
filters, which are easier to program from kernel. Eventually,
all of these values will come down from user space for better
quality.

Signed-off-by: Stephane Viau <sviau@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>
diff --git a/drivers/gpu/drm/msm/mdp/mdp_kms.h b/drivers/gpu/drm/msm/mdp/mdp_kms.h
index 46a94e7..0af2a54 100644
--- a/drivers/gpu/drm/msm/mdp/mdp_kms.h
+++ b/drivers/gpu/drm/msm/mdp/mdp_kms.h
@@ -106,6 +106,7 @@
 #define MDP_PIPE_CAP_SCALE			BIT(2)
 #define MDP_PIPE_CAP_CSC			BIT(3)
 #define MDP_PIPE_CAP_DECIMATION			BIT(4)
+#define MDP_PIPE_CAP_SW_PIX_EXT			BIT(5)
 
 static inline bool pipe_supports_yuv(uint32_t pipe_caps)
 {