sunxi: use 6MHz PLL_VIDEO step for DE2 for higher resolution LCD

DE2 SoCs can support LCDs up to 1080p (e.g. A64), and 3MHz step won't
let PLL_VIDEO be high enough for them.

Use 6MHz step for PLL_VIDEO when using DE2, to satisfy 1080p LCD.

Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
Signed-off-by: Vasily Khoruzhick <anarsoul@gmail.com>
Tested-by: Vasily Khoruzhick <anarsoul@gmail.com>
Acked-by: Maxime Ripard <maxime.ripard@bootlin.com>
Acked-by: Jagan Teki <jagan@openedev.com>

arch/arm/mach-sunxi/clock_sun6i.c

@@ -149,7 +149,11 @@ void clock_set_pll3(unsigned int clk)
 {
 	struct sunxi_ccm_reg * const ccm =
 		(struct sunxi_ccm_reg *)SUNXI_CCM_BASE;
+#ifdef CONFIG_SUNXI_DE2
+	const int m = 4; /* 6 MHz steps to allow higher frequency for DE2 */
+#else
 	const int m = 8; /* 3 MHz steps just like sun4i, sun5i and sun7i */
+#endif
 
 	if (clk == 0) {
 		clrbits_le32(&ccm->pll3_cfg, CCM_PLL3_CTRL_EN);

drivers/video/sunxi/lcdc.c

@@ -211,11 +211,17 @@ void lcdc_tcon1_mode_set(struct sunxi_lcdc_reg * const lcdc,
 void lcdc_pll_set(struct sunxi_ccm_reg *ccm, int tcon, int dotclock,
 		  int *clk_div, int *clk_double, bool is_composite)
 {
-	int value, n, m, min_m, max_m, diff;
+	int value, n, m, min_m, max_m, diff, step;
 	int best_n = 0, best_m = 0, best_diff = 0x0FFFFFFF;
 	int best_double = 0;
 	bool use_mipi_pll = false;
 
+#ifdef CONFIG_SUNXI_DE2
+	step = 6000;
+#else
+	step = 3000;
+#endif
+
 	if (tcon == 0) {
 #if defined(CONFIG_VIDEO_LCD_IF_PARALLEL) || defined(CONFIG_SUNXI_DE2)
 		min_m = 6;
@@ -237,10 +243,10 @@ void lcdc_pll_set(struct sunxi_ccm_reg *ccm, int tcon, int dotclock,
 	 */
 	for (m = min_m; m <= max_m; m++) {
 #ifndef CONFIG_SUNXI_DE2
-		n = (m * dotclock) / 3000;
+		n = (m * dotclock) / step;
 
 		if ((n >= 9) && (n <= 127)) {
-			value = (3000 * n) / m;
+			value = (step * n) / m;
 			diff = dotclock - value;
 			if (diff < best_diff) {
 				best_diff = diff;
@@ -256,9 +262,9 @@ void lcdc_pll_set(struct sunxi_ccm_reg *ccm, int tcon, int dotclock,
 #endif
 
 		/* No double clock on DE2 */
-		n = (m * dotclock) / 6000;
+		n = (m * dotclock) / (step * 2);
 		if ((n >= 9) && (n <= 127)) {
-			value = (6000 * n) / m;
+			value = (step * 2 * n) / m;
 			diff = dotclock - value;
 			if (diff < best_diff) {
 				best_diff = diff;
@@ -287,11 +293,11 @@ void lcdc_pll_set(struct sunxi_ccm_reg *ccm, int tcon, int dotclock,
 	} else
 #endif
 	{
-		clock_set_pll3(best_n * 3000000);
-		debug("dotclock: %dkHz = %dkHz: (%d * 3MHz * %d) / %d\n",
+		clock_set_pll3(best_n * step * 1000);
+		debug("dotclock: %dkHz = %dkHz: (%d * %dkHz * %d) / %d\n",
 		      dotclock,
 		      (best_double + 1) * clock_get_pll3() / best_m / 1000,
-		      best_double + 1, best_n, best_m);
+		      best_double + 1, step, best_n, best_m);
 	}
 
 	if (tcon == 0) {