tegra132: rename clock_display() to clock_configure_plld()

Provide an explicit name for configuring PLLD. The new name,
clock_configure_plld(), provides an explicit semantic to
what it is doing. Also, provide the printk() about actual
frequency vs requested frequency as most of the callers
were doing this themselves.

BUG=chrome-os-partner:33825
BRANCH=None
TEST=Built and booted on ryu.

Change-Id: I1880f0f305e69674922b070d282aac3acdc86aad
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: c51d5b0864d8bd0db5927380803cec46ccd74d48
Original-Change-Id: If744332b466d9486f83b08d0ab4e9006fadfecdd
Original-Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/230773
Original-Reviewed-by: Furquan Shaikh <furquan@chromium.org>
Original-Reviewed-by: Tom Warren <twarren@nvidia.com>
Original-Reviewed-by: Sean Paul <seanpaul@chromium.org>
Reviewed-on: http://review.coreboot.org/9524
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

src/soc/nvidia/tegra132/clock.c

@@ -291,10 +291,6 @@ static void graphics_pll(void)
 	/* leave dither and undoc bits set, release clamp */
 	scfg = (1<<28) | (1<<24);
 	writel(scfg, cfg);
-
-	/* disp1 will be set when panel information (pixel clock) is
-	 * retrieved (clock_display).
-	 */
 }
 
 /*
@@ -304,8 +300,7 @@ static void graphics_pll(void)
  *
  * Return the plld frequency if success, otherwise return 0.
  */
-u32
-clock_display(u32 frequency)
+u32 clock_configure_plld(u32 frequency)
 {
 	/**
 	 * plld (fo) = vco >> p, where 500MHz < vco < 1000MHz
@@ -388,6 +383,10 @@ clock_display(u32 frequency)
 	init_pll(CLK_RST_REG(plld_base), CLK_RST_REG(plld_misc), plld,
 		 (PLLUD_MISC_LOCK_ENABLE | PLLD_MISC_CLK_ENABLE));
 
+	if (rounded_rate != frequency)
+		printk(BIOS_DEBUG, "PLLD rate: %u vs %u\n", rounded_rate,
+			frequency);
+
 	return rounded_rate;
 }
 

src/soc/nvidia/tegra132/display.c

@@ -135,7 +135,8 @@ static int update_display_mode(struct display_controller *disp_ctrl,
 	 * has some requirements to have VCO in range 500MHz~1000MHz (see
 	 * clock.c for more detail). To simplify calculation, we set
 	 * PixelClockDiv to 1 and ShiftClockDiv to 1. In future these values
-	 * may be calculated by clock_display, to allow wider frequency range.
+	 * may be calculated by clock_configure_plld(), to allow wider
+	 * frequency range.
 	 *
 	 * Note ShiftClockDiv is a 7.1 format value.
 	 */
@@ -265,12 +266,10 @@ void display_startup(device_t dev)
 	 * update_display_mode() for detail.
 	 */
 	/* set default plld */
-	plld_rate = clock_display(config->pixel_clock * 2);
+	plld_rate = clock_configure_plld(config->pixel_clock * 2);
 	if (plld_rate == 0) {
 		printk(BIOS_ERR, "dc: clock init failed\n");
 		return;
-	} else if (plld_rate != config->pixel_clock * 2) {
-		printk(BIOS_WARNING, "dc: plld rounded to %u\n", plld_rate);
 	}
 
 	/* set disp1's clock source to PLLD_OUT0 */

src/soc/nvidia/tegra132/include/soc/clock.h

@@ -378,7 +378,11 @@ static inline void _clock_set_div(u32 *reg, const char *name, u32 div,
 
 int clock_get_osc_khz(void);
 int clock_get_pll_input_khz(void);
-u32 clock_display(u32 frequency);
+/*
+ * Configure PLLD to requested frequency. Returned value is closest match
+ * within the PLLD's constraints or 0 if an error.
+ */
+u32 clock_configure_plld(u32 frequency);
 void clock_early_uart(void);
 void clock_external_output(int clk_id);
 void clock_sdram(u32 m, u32 n, u32 p, u32 setup, u32 ph45, u32 ph90,

src/soc/nvidia/tegra132/tegra_dsi.c

@@ -463,7 +463,7 @@ static int tegra_output_dsi_setup_clock(struct tegra_dsi *dsi,
 		dsi->slave->clk_rate = dsi->clk_rate;
 
 	/* set up plld */
-	plld = clock_display(plld);
+	plld = clock_configure_plld(plld);
 	if (plld == 0) {
                 printk(BIOS_ERR, "%s: clock init failed\n", __func__);
                 return -1;