imx: mx6: lcdif: gate clock before changing mux

The mux for the lcd clock is not glitchless,
so need to first gate the clock before changing the mux.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Cc: Stefano Babic <sbabic@denx.de>

arch/arm/cpu/armv7/mx6/clock.c

@@ -771,6 +771,16 @@ int enable_lcdif_clock(u32 base_addr)
 		return 0;
 	}
 
+	/* Gate LCDIF clock first */
+	reg = readl(&imx_ccm->CCGR3);
+	reg &= ~lcdif_ccgr3_mask;
+	writel(reg, &imx_ccm->CCGR3);
+
+	reg = readl(&imx_ccm->CCGR2);
+	reg &= ~MXC_CCM_CCGR2_LCD_MASK;
+	writel(reg, &imx_ccm->CCGR2);
+
+	/* Select pre-mux */
 	reg = readl(&imx_ccm->cscdr2);
 	reg &= ~lcdif_clk_sel_mask;
 	writel(reg, &imx_ccm->cscdr2);