drm/panel: ilitek-ili9881c: Explicitly set address mode, allow 180° rotation

We can use horizontal and vertical flipping via the MIPI DCS address
mode to rotate the display by 180° using the device tree "rotation"
property. Since the tl050hdv35 panel has been defined as rotated,
we have to invert the bits there.

Signed-off-by: Philipp Zabel <[e-mail]>
Reviewed-by: Neil Armstrong <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Neil Armstrong <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/panel/panel-ilitek-ili9881c.c

···
 	const size_t init_length;
 	const struct drm_display_mode *mode;
 	const unsigned long mode_flags;
+	u8 default_address_mode;
 };
 
 struct ili9881c {
···
 	struct gpio_desc	*reset;
 
 	enum drm_panel_orientation	orientation;
+	u8 address_mode;
 };
 
 #define ILI9881C_SWITCH_PAGE_INSTR(_page)	\
···
 	ILI9881C_COMMAND_INSTR(0xd1, 0x4b),
 	ILI9881C_COMMAND_INSTR(0xd2, 0x60),
 	ILI9881C_COMMAND_INSTR(0xd3, 0x39),
-	ILI9881C_SWITCH_PAGE_INSTR(0),
-	ILI9881C_COMMAND_INSTR(0x36, 0x03),
 };
 
 static const struct ili9881c_instr w552946ab_init[] = {
···
 	if (ret)
 		return ret;
 
+	if (ctx->address_mode) {
+		ret = mipi_dsi_dcs_write(ctx->dsi, MIPI_DCS_SET_ADDRESS_MODE,
+					 &ctx->address_mode,
+					 sizeof(ctx->address_mode));
+		if (ret < 0)
+			return ret;
+	}
+
 	ret = mipi_dsi_dcs_set_tear_on(ctx->dsi, MIPI_DSI_DCS_TEAR_MODE_VBLANK);
 	if (ret)
 		return ret;
···
 		return ret;
 	}
 
+	ctx->address_mode = ctx->desc->default_address_mode;
+	if (ctx->orientation == DRM_MODE_PANEL_ORIENTATION_BOTTOM_UP) {
+		ctx->address_mode ^= 0x03;
+		ctx->orientation = DRM_MODE_PANEL_ORIENTATION_NORMAL;
+	}
+
 	ctx->panel.prepare_prev_first = true;
 
 	ret = drm_panel_of_backlight(&ctx->panel);
···
 	.mode = &tl050hdv35_default_mode,
 	.mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_SYNC_PULSE |
 		      MIPI_DSI_MODE_LPM,
+	.default_address_mode = 0x03,
 };
 
 static const struct ili9881c_desc w552946aba_desc = {