sunxi: video: Modify sunxi_lcdc_pll_set to work with both tcon0 and tcon1

Modify sunxi_lcdc_pll_set to work with both tcon0 and tcon1, this is a
preparation patch for adding lcd support.

While at it also swap the divider search order, searching from low to
high, as the comment above the code says we should do. In cases where there
are multiple solutions this will result in picking a lower pll clock and
divider, which is more stable and saves power.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Ian Campbell <ijc@hellion.org.uk>

arch/arm/include/asm/arch-sunxi/clock_sun6i.h

@@ -255,6 +255,8 @@ struct sunxi_ccm_reg {
 #define CCM_LCD_CH0_CTRL_PLL3_2X	(2 << 24)
 #define CCM_LCD_CH0_CTRL_PLL7_2X	(3 << 24)
 #define CCM_LCD_CH0_CTRL_MIPI_PLL	(4 << 24)
+/* No reset bit in ch0_clk_cfg (reset is controlled through ahb_reset1) */
+#define CCM_LCD_CH0_CTRL_RST		0
 #define CCM_LCD_CH0_CTRL_GATE		(0x1 << 31)
 
 #define CCM_LCD_CH1_CTRL_M(n)		((((n) - 1) & 0xf) << 0)

drivers/video/sunxi_display.c

@@ -323,20 +323,29 @@ static void sunxi_composer_enable(void)
 /*
  * LCDC, what allwinner calls a CRTC, so timing controller and serializer.
  */
-static void sunxi_lcdc_pll_set(int dotclock, int *clk_div, int *clk_double)
+static void sunxi_lcdc_pll_set(int tcon, int dotclock,
+			       int *clk_div, int *clk_double)
 {
 	struct sunxi_ccm_reg * const ccm =
 		(struct sunxi_ccm_reg *)SUNXI_CCM_BASE;
-	int value, n, m, diff;
+	int value, n, m, min_m, max_m, diff;
 	int best_n = 0, best_m = 0, best_diff = 0x0FFFFFFF;
 	int best_double = 0;
 
+	if (tcon == 0) {
+		min_m = 6;
+		max_m = 127;
+	} else {
+		min_m = 1;
+		max_m = 15;
+	}
+
 	/*
 	 * Find the lowest divider resulting in a matching clock, if there
 	 * is no match, pick the closest lower clock, as monitors tend to
 	 * not sync to higher frequencies.
 	 */
-	for (m = 15; m > 0; m--) {
+	for (m = min_m; m <= max_m; m++) {
 		n = (m * dotclock) / 3000;
 
 		if ((n >= 9) && (n <= 127)) {
@@ -373,9 +382,17 @@ static void sunxi_lcdc_pll_set(int dotclock, int *clk_div, int *clk_double)
 
 	clock_set_pll3(best_n * 3000000);
 
+	if (tcon == 0) {
+		writel(CCM_LCD_CH0_CTRL_GATE | CCM_LCD_CH0_CTRL_RST |
+		       (best_double ? CCM_LCD_CH0_CTRL_PLL3_2X :
+				      CCM_LCD_CH0_CTRL_PLL3),
+		       &ccm->lcd0_ch0_clk_cfg);
+	} else {
 		writel(CCM_LCD_CH1_CTRL_GATE |
-	    (best_double ? CCM_LCD_CH1_CTRL_PLL3_2X : CCM_LCD_CH1_CTRL_PLL3) |
+		       (best_double ? CCM_LCD_CH1_CTRL_PLL3_2X :
+				      CCM_LCD_CH1_CTRL_PLL3) |
 		       CCM_LCD_CH1_CTRL_M(best_m), &ccm->lcd0_ch1_clk_cfg);
+	}
 
 	*clk_div = best_m;
 	*clk_double = best_double;
@@ -453,7 +470,7 @@ static void sunxi_lcdc_tcon1_mode_set(const struct ctfb_res_modes *mode,
 	writel(SUNXI_LCDC_X(mode->hsync_len) | SUNXI_LCDC_Y(mode->vsync_len),
 	       &lcdc->tcon1_timing_sync);
 
-	sunxi_lcdc_pll_set(mode->pixclock_khz, clk_div, clk_double);
+	sunxi_lcdc_pll_set(1, mode->pixclock_khz, clk_div, clk_double);
 }
 
 #ifdef CONFIG_MACH_SUN6I