drm/tegra: Support bottom-up buffer objects

The gr3d engine renders images bottom-up. Allow buffers that are used
for 3D content to be marked as such and implement support in the display
controller to present them properly.

Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
Signed-off-by: Thierry Reding <treding@nvidia.com>
diff --git a/drivers/gpu/drm/tegra/dc.c b/drivers/gpu/drm/tegra/dc.c
index c51aaf7..ae1cb31e 100644
--- a/drivers/gpu/drm/tegra/dc.c
+++ b/drivers/gpu/drm/tegra/dc.c
@@ -47,6 +47,7 @@
 	window.dst.h = crtc_h;
 	window.format = tegra_dc_format(fb->pixel_format);
 	window.bits_per_pixel = fb->bits_per_pixel;
+	window.bottom_up = tegra_fb_is_bottom_up(fb);
 	window.tiled = tegra_fb_is_tiled(fb);
 
 	for (i = 0; i < drm_format_num_planes(fb->pixel_format); i++) {
@@ -147,6 +148,7 @@
 {
 	unsigned int format = tegra_dc_format(fb->pixel_format);
 	struct tegra_bo *bo = tegra_fb_get_plane(fb, 0);
+	unsigned int h_offset = 0, v_offset = 0;
 	unsigned long value;
 
 	tegra_dc_writel(dc, WINDOW_A_SELECT, DC_CMD_DISPLAY_WINDOW_HEADER);
@@ -168,6 +170,22 @@
 
 	tegra_dc_writel(dc, value, DC_WIN_BUFFER_ADDR_MODE);
 
+	/* make sure bottom-up buffers are properly displayed */
+	if (tegra_fb_is_bottom_up(fb)) {
+		value = tegra_dc_readl(dc, DC_WIN_WIN_OPTIONS);
+		value |= INVERT_V;
+		tegra_dc_writel(dc, value, DC_WIN_WIN_OPTIONS);
+
+		v_offset += fb->height - 1;
+	} else {
+		value = tegra_dc_readl(dc, DC_WIN_WIN_OPTIONS);
+		value &= ~INVERT_V;
+		tegra_dc_writel(dc, value, DC_WIN_WIN_OPTIONS);
+	}
+
+	tegra_dc_writel(dc, h_offset, DC_WINBUF_ADDR_H_OFFSET);
+	tegra_dc_writel(dc, v_offset, DC_WINBUF_ADDR_V_OFFSET);
+
 	value = GENERAL_UPDATE | WIN_A_UPDATE;
 	tegra_dc_writel(dc, value, DC_CMD_STATE_CONTROL);
 
@@ -517,6 +535,9 @@
 		tegra_dc_writel(dc, window->stride[0], DC_WIN_LINE_STRIDE);
 	}
 
+	if (window->bottom_up)
+		v_offset += window->src.h - 1;
+
 	tegra_dc_writel(dc, h_offset, DC_WINBUF_ADDR_H_OFFSET);
 	tegra_dc_writel(dc, v_offset, DC_WINBUF_ADDR_V_OFFSET);
 
@@ -548,6 +569,9 @@
 		value |= COLOR_EXPAND;
 	}
 
+	if (window->bottom_up)
+		value |= INVERT_V;
+
 	tegra_dc_writel(dc, value, DC_WIN_WIN_OPTIONS);
 
 	/*