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

[Tom Warren]

Thierry,

> -----Original Message-----
> From: Thierry Reding [mailto:thierry.reding at gmail.com]
> Sent: Tuesday, September 08, 2015 2:38 AM
> To: Tom Warren
> Cc: Nicolas Chauvet; u-boot at lists.denx.de
> Subject: [PATCH 2/2] ARM: tegra114: Clear IDDQ when enabling PLLC
> 
> From: Thierry Reding <treding at 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.
Do we need this for T210, too? A quick glance at the TRM shows IDDQ for PLLA, M, C, U, P, D.

I'll get these two in for the next PR.

Tom
--
nvpublic
> 
> Signed-off-by: Thierry Reding <treding at 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