[U-Boot] [PATCH 11/14] sunxi: Fill memory before comparing it when doing dram init on sun6i

[Ian Campbell <ijc@hellion.org.uk>]

On Tue, 2014-12-16 at 21:31 +0100, Hans de Goede wrote:
> The sun8i boot0 code fills the DRAM with a "random" pattern before comparing
> it at different offsets to do columns, etc. detection. The sun6i boot0 code
> does not do it, but it seems like a good idea to do this regardless.

Is this the right way round? The existing sun6i code (which you are
moving here) seems to _rely_ on something having written a useful
pattern, which I would have assumed to have been boot0. Or else how does
it work now? Chance?

> The new mctl_mem_fill function this introduces is added as an inline helper
> in dram.h, so that it can be shared with the sun8i dram code.
> 
> While at it move mctl_mem_matches to dram.h for re-use in sun8i too.
> 
> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
> ---
>  arch/arm/cpu/armv7/sunxi/dram_sun6i.c  | 15 +--------------
>  arch/arm/include/asm/arch-sunxi/dram.h | 29 +++++++++++++++++++++++++++++
>  2 files changed, 30 insertions(+), 14 deletions(-)
> 
> diff --git a/arch/arm/cpu/armv7/sunxi/dram_sun6i.c b/arch/arm/cpu/armv7/sunxi/dram_sun6i.c
> index e1670e5..4675c48 100644
> --- a/arch/arm/cpu/armv7/sunxi/dram_sun6i.c
> +++ b/arch/arm/cpu/armv7/sunxi/dram_sun6i.c
> @@ -326,20 +326,6 @@ static void mctl_port_cfg(void)
>  	writel(0x00000307, &mctl_com->mbagcr[5]);
>  }
>  
> -static bool mctl_mem_matches(u32 offset)
> -{
> -	const int match_count = 64;
> -	int i, matches = 0;
> -
> -	for (i = 0; i < match_count; i++) {
> -		if (readl(CONFIG_SYS_SDRAM_BASE + i * 4) ==
> -		    readl(CONFIG_SYS_SDRAM_BASE + offset + i * 4))
> -			matches++;
> -	}
> -
> -	return matches == match_count;
> -}
> -
>  unsigned long sunxi_dram_init(void)
>  {
>  	struct sunxi_mctl_com_reg * const mctl_com =
> @@ -391,6 +377,7 @@ unsigned long sunxi_dram_init(void)
>  		    MCTL_CR_BANK(1) | MCTL_CR_RANK(1));
>  
>  	/* Detect and set page size */
> +	mctl_mem_fill();
>  	for (columns = 7; columns < 20; columns++) {
>  		if (mctl_mem_matches(1 << columns))
>  			break;
> diff --git a/arch/arm/include/asm/arch-sunxi/dram.h b/arch/arm/include/asm/arch-sunxi/dram.h
> index 18924f5..0bf718c 100644
> --- a/arch/arm/include/asm/arch-sunxi/dram.h
> +++ b/arch/arm/include/asm/arch-sunxi/dram.h
> @@ -22,6 +22,8 @@
>  #include <asm/arch/dram_sun4i.h>
>  #endif
>  
> +#define MCTL_MEM_FILL_MATCH_COUNT 64
> +
>  unsigned long sunxi_dram_init(void);
>  
>  /*
> @@ -37,4 +39,31 @@ static inline void mctl_await_completion(u32 *reg, u32 mask, u32 val)
>  	}
>  }
>  
> +/*
> + * Fill beginning of DRAM with "random" data for mctl_mem_matches()
> + */
> +static inline void mctl_mem_fill(void)
> +{
> +	int i;
> +
> +	for (i = 0; i < MCTL_MEM_FILL_MATCH_COUNT; i++)
> +		writel(0xaa55aa55 + i, CONFIG_SYS_SDRAM_BASE + i * 4);
> +}
> +
> +/*
> + * Test if memory at offset offset matches memory at begin of DRAM
> + */
> +static inline bool mctl_mem_matches(u32 offset)
> +{
> +	int i, matches = 0;
> +
> +	for (i = 0; i < MCTL_MEM_FILL_MATCH_COUNT; i++) {
> +		if (readl(CONFIG_SYS_SDRAM_BASE + i * 4) ==
> +		    readl(CONFIG_SYS_SDRAM_BASE + offset + i * 4))
> +			matches++;
> +	}
> +
> +	return matches == MCTL_MEM_FILL_MATCH_COUNT;
> +}
> +
>  #endif /* _SUNXI_DRAM_H */