[U-Boot] [PATCH 2/2] ARM: tegra114: Clear IDDQ when enabling PLLC

Thierry Reding
2015-09-08T09:38:04Z

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"). The Tegra114 TRM doesn't contain this information, but
the programming of PLLC is the same on Tegra114 and Tegra124.

Signed-off-by: Thierry Reding <treding@nvidia.com>
---
arch/arm/include/asm/arch-tegra114/clock.h | 3 +++
arch/arm/mach-tegra/tegra114/clock.c | 5 +++++
2 files changed, 8 insertions(+)

diff --git a/arch/arm/include/asm/arch-tegra114/clock.h b/arch/arm/include/asm/arch-tegra114/clock.h
index abbefcd0e456..9bee39778747 100644
--- a/arch/arm/include/asm/arch-tegra114/clock.h
+++ b/arch/arm/include/asm/arch-tegra114/clock.h
@@ -25,4 +25,7 @@
#define OSC_FREQ_SHIFT 28
#define OSC_FREQ_MASK (0xF << OSC_FREQ_SHIFT)

+/* CLK_RST_CONTROLLER_PLLC_MISC_0 */
+#define PLLC_IDDQ (1 << 26)
+
#endif /* _TEGRA114_CLOCK_H_ */
diff --git a/arch/arm/mach-tegra/tegra114/clock.c b/arch/arm/mach-tegra/tegra114/clock.c
index cec843b27df7..e6ef873c8dc4 100644
--- a/arch/arm/mach-tegra/tegra114/clock.c
+++ b/arch/arm/mach-tegra/tegra114/clock.c
@@ -629,6 +629,11 @@ 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