[U-Boot] [PATCH 1/2] arm: imx6: Add DDR3 calibration code for MX6 Q/D/DL

[Eric Nelson]

Hi Marek,

On 12/16/2015 07:40 AM, Marek Vasut wrote:
> Add DDR3 calibration code for i.MX6Q, i.MX6D and i.MX6DL. This code
> fine-tunes the behavior of the MMDC controller in order to improve
> the signal integrity and memory stability.
> 

I'm glad to see that others are interested in this.

I've been working on something similar, but struggling to have time
to finish and clean it up:
	https://github.com/ericnelsonaz/u-boot/tree/memcal-pass1

My aim is/was a bit different though, and aims to be a replacement for
the DDR stress tool, which is cumbersome to use.

To do that, I put together a pseudo-board with Kconfig options for
the serial console, memory bus width, and such.

> Signed-off-by: Marek Vasut <marex at denx.de>
> Cc: Stefano Babic <sbabic at denx.de>
> ---
>  arch/arm/cpu/armv7/mx6/ddr.c            | 559 ++++++++++++++++++++++++++++++++
>  arch/arm/include/asm/arch-mx6/mx6-ddr.h |   5 +
>  2 files changed, 564 insertions(+)
> 
> diff --git a/arch/arm/cpu/armv7/mx6/ddr.c b/arch/arm/cpu/armv7/mx6/ddr.c
> index 6b039e4..194411f 100644
> --- a/arch/arm/cpu/armv7/mx6/ddr.c
> +++ b/arch/arm/cpu/armv7/mx6/ddr.c
> @@ -13,6 +13,565 @@
>  #include <asm/io.h>
>  #include <asm/types.h>
>  

I'll review this in detail later, but off-hand, I think this could use
a new CONFIG_ variable to exclude it from boards that don't use it.

It also shouldn't be difficult to support i.MX6SL and LPDDR here.

> +#if defined(CONFIG_MX6QDL) || defined(CONFIG_MX6Q) || defined(CONFIG_MX6D)
> +
> +static int wait_for_bit(void *reg, const uint32_t mask, bool set)
> +{
> +	unsigned int timeout = 1000;
> +	u32 val;
> +

Regards,


Eric