[U-Boot] [linux-sunxi] [PATCH] sunxi: Tune H3 DRAM PLL to improve lock time

[Hans de Goede]

Hi,

On 19-08-16 13:40, Jens Kuske wrote:
> The H3 PLL5 used for DRAM barely manages to lock to the required
> frequency before DRAM controller starts, sometimes leading to wrong
> delay-line calibration results.
> This patch changes the PLL tuning parameters to the same values as
> boot0 used, which speeds up the locking and fixes the problem.
>
> Signed-off-by: Jens Kuske <jenskuske at gmail.com>

Thanks, I've added this to my local tree. I'm currently running
some tests, once those are done I plan to submit a pull-req
for v2016.09 which will include this patch.

Regards,

Hans



>
> ---
>
> Hi all,
>
> this might fix some of the DRAM reliability problems seen on H3 boards,
> but I could only test it on one board myself, where it only improves
> results for dram clocks above 648 MHz. But my board didn't suffer
> from reliability problems at 672 MHz, so maybe it helps on boards
> where 672 isn't stable.
> Even if there are no visible effects on reliability, this is what
> boot0 does, and it definitely fixes something, see table below:
>
> DRAM clock	delay steps
> 		without patch	with patch
>
> 552 MHz:	36		36
> 576 MHz:	35		35
> 600 MHz:	34		34
> 624 MHz:	32		32
> 648 MHz:	31		31
> 672 MHz:	31		30
> 696 MHz:	31		29
> 720 MHz:	31		28
> 744 MHz:	31		27
> 768 MHz:	31		26
>
> Looks like the clock only reached ~648 MHz when calibration is run,
> leading to increasing error for higher clocks.
> If someone wants to reproduce this test, the delays are from the
> DXnLCDL1 registers (0x01c63308 + 0..3 * 0x80) and are responsible
> for phase-shifting DQS signals by 90deg relative to DQ.
>
> Best Regards,
> Jens
>
> ---
>  arch/arm/include/asm/arch-sunxi/clock_sun6i.h | 9 ++++++++-
>  arch/arm/mach-sunxi/clock_sun6i.c             | 6 ++++++
>  2 files changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm/include/asm/arch-sunxi/clock_sun6i.h b/arch/arm/include/asm/arch-sunxi/clock_sun6i.h
> index d4dff1e..be9fcfd 100644
> --- a/arch/arm/include/asm/arch-sunxi/clock_sun6i.h
> +++ b/arch/arm/include/asm/arch-sunxi/clock_sun6i.h
> @@ -116,7 +116,9 @@ struct sunxi_ccm_reg {
>  	u32 mipi_bias_cfg;	/* 0x240 MIPI Bias config */
>  	u32 pll9_bias_cfg;	/* 0x244 PLL9 Bias config */
>  	u32 pll10_bias_cfg;	/* 0x248 PLL10 Bias config */
> -	u32 reserved21[13];
> +	u32 reserved21[5];
> +	u32 pll5_tuning_cfg;	/* 0x260 PLL5 Tuning config */
> +	u32 reserved21_5[7];
>  	u32 pll1_pattern_cfg;	/* 0x280 PLL1 Pattern config */
>  	u32 pll2_pattern_cfg;	/* 0x284 PLL2 Pattern config */
>  	u32 pll3_pattern_cfg;	/* 0x288 PLL3 Pattern config */
> @@ -223,6 +225,11 @@ struct sunxi_ccm_reg {
>  #define CCM_PLL11_CTRL_UPD		(0x1 << 30)
>  #define CCM_PLL11_CTRL_EN		(0x1 << 31)
>
> +#define CCM_PLL5_TUN_LOCK_TIME(x)	(((x) & 0x7) << 24)
> +#define CCM_PLL5_TUN_LOCK_TIME_MASK	CCM_PLL5_TUN_LOCK_TIME(0x7)
> +#define CCM_PLL5_TUN_INIT_FREQ(x)	(((x) & 0x7f) << 16)
> +#define CCM_PLL5_TUN_INIT_FREQ_MASK	CCM_PLL5_TUN_INIT_FREQ(0x7f)
> +
>  #if defined(CONFIG_MACH_SUN50I)
>  /* AHB1=100MHz failsafe setup from the FEL mode, usable with PMIC defaults */
>  #define AHB1_ABP1_DIV_DEFAULT		0x00003190 /* AHB1=PLL6/6,APB1=AHB1/2 */
> diff --git a/arch/arm/mach-sunxi/clock_sun6i.c b/arch/arm/mach-sunxi/clock_sun6i.c
> index 15272c9..ed8cd9b 100644
> --- a/arch/arm/mach-sunxi/clock_sun6i.c
> +++ b/arch/arm/mach-sunxi/clock_sun6i.c
> @@ -148,6 +148,12 @@ void clock_set_pll5(unsigned int clk, bool sigma_delta_enable)
>  	const int max_n = 32;
>  	int k = 1, m = 2;
>
> +#ifdef CONFIG_MACH_SUN8I_H3
> +	clrsetbits_le32(&ccm->pll5_tuning_cfg, CCM_PLL5_TUN_LOCK_TIME_MASK |
> +			CCM_PLL5_TUN_INIT_FREQ_MASK,
> +			CCM_PLL5_TUN_LOCK_TIME(2) | CCM_PLL5_TUN_INIT_FREQ(16));
> +#endif
> +
>  	if (sigma_delta_enable)
>  		writel(CCM_PLL5_PATTERN, &ccm->pll5_pattern_cfg);
>
>