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

Ian Campbell
2014-12-18T19:12:13Z

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 */