ARM: imx51: Configure M4IF to avoid visual artifacts

Configure the M4IF registers as per the vendor bootloader
to avoid visual artifacts during video playback.

This way we don't need to rely on the bootloader configuration for
optimal IPU/VPU bus priorities.
Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Tested-by: Sergey Lapin <sergey.lapin@cogentembedded.com>
Reviewed-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/mach-imx/mach-imx51.c

@@ -12,6 +12,7 @@
 
 #include <linux/io.h>
 #include <linux/irq.h>
+#include <linux/of_address.h>
 #include <linux/of_irq.h>
 #include <linux/of_platform.h>
 #include <asm/mach/arch.h>
@@ -48,11 +49,37 @@ static void __init imx51_ipu_mipi_setup(void)
 	iounmap(hsc_addr);
 }
 
+static void __init imx51_m4if_setup(void)
+{
+	void __iomem *m4if_base;
+	struct device_node *np;
+
+	np = of_find_compatible_node(NULL, NULL, "fsl,imx51-m4if");
+	if (!np)
+		return;
+
+	m4if_base = of_iomap(np, 0);
+	if (!m4if_base) {
+		pr_err("Unable to map M4IF registers\n");
+		return;
+	}
+
+	/*
+	 * Configure VPU and IPU with higher priorities
+	 * in order to avoid artifacts during video playback
+	 */
+	writel_relaxed(0x00000203, m4if_base + 0x40);
+	writel_relaxed(0x00000000, m4if_base + 0x44);
+	writel_relaxed(0x00120125, m4if_base + 0x9c);
+	writel_relaxed(0x001901A3, m4if_base + 0x48);
+	iounmap(m4if_base);
+}
+
 static void __init imx51_dt_init(void)
 {
 	imx51_ipu_mipi_setup();
 	imx_src_init();
-
+	imx51_m4if_setup();
 	imx_aips_allow_unprivileged_access("fsl,imx51-aipstz");
 }