[U-Boot] [PATCH 1/2] ARM: tegra124: Clear IDDQ when enabling PLLC

Thierry Reding
2015-09-08T09:38:03Z

From: Thierry Reding <treding@nvidia.com>

Enabling a PLL while IDDQ is high. The Linux kernel checks for this
condition and warns about it verbosely, so while this seems to work
fine, fix it up according to the programming guidelines provided in
the Tegra K1 TRM (v02p), Section 5.3.8.1 ("PLLC and PLLC4 Startup
Sequence").

Reported-by: Nicolas Chauvet <kwizart@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
---
arch/arm/include/asm/arch-tegra124/clock.h | 3 +++
arch/arm/mach-tegra/tegra124/clock.c | 5 +++++
2 files changed, 8 insertions(+)

diff --git a/arch/arm/include/asm/arch-tegra124/clock.h b/arch/arm/include/asm/arch-tegra124/clock.h
index e202cc5a7f46..ff99b9dfafda 100644
--- a/arch/arm/include/asm/arch-tegra124/clock.h
+++ b/arch/arm/include/asm/arch-tegra124/clock.h
@@ -16,6 +16,9 @@
#define OSC_FREQ_SHIFT 28
#define OSC_FREQ_MASK (0xF << OSC_FREQ_SHIFT)

+/* CLK_RST_CONTROLLER_PLLC_MISC_0 */
+#define PLLC_IDDQ (1 << 26)
+
/* CLK_RST_CONTROLLER_CLK_SOURCE_SOR0_0 */
#define SOR0_CLK_SEL0 (1 << 14)
#define SOR0_CLK_SEL1 (1 << 15)
diff --git a/arch/arm/mach-tegra/tegra124/clock.c b/arch/arm/mach-tegra/tegra124/clock.c
index aa046e8950f7..1e71146236e9 100644
--- a/arch/arm/mach-tegra/tegra124/clock.c
+++ b/arch/arm/mach-tegra/tegra124/clock.c
@@ -809,6 +809,11 @@ void clock_early_init(void)

tegra30_set_up_pllp();

+ /* clear IDDQ before accessing any other PLLC registers */
+ pllinfo = &tegra_pll_info_table[CLOCK_ID_CGENERAL];
+ clrbits_le32(&clkrst->crc_pll[CLOCK_ID_CGENERAL].pll_misc, PLLC_IDDQ);
+ udelay(2);
+
/*
* PLLC output frequency set to 600Mhz
* PLLD output frequency set to 925Mhz
--
2.5.0