[U-Boot] [linux-sunxi] Re: [PATCH 3/5] sunxi: add 3GiB DRAM detection support in main U-Boot
Icenowy Zheng
icenowy at aosc.io
Thu Feb 8 07:03:51 UTC 2018
在 2018-02-08 08:37,André Przywara 写道:
> On 07/02/18 19:35, Icenowy Zheng wrote:
>
> Hi,
>
>> Some Allwinner SoCs can use 3GiB DRAM (part of 4GiB or larger module).
>>
>> As the common get_ram_size function cannot detect non-pow-of-2 memory,
>> add special detect code into the DRAM size code in main U-Boot.
>
> The original get_ram_size() function is slightly dodgy already (as it
> probes memory by writing). And in general we will never be able to
> cover
> ARMv7/LPAE machines easily with our current static identify mapping -
> regardless of any probing hacks we pull up.
>
> So I was wondering if we could either:
> - somehow pass the result of sunxi_dram_init() to U-Boot proper, or
> - call the DRAM size determination routine again
>
> This would give us the definite answer, and would be correct in every
> case. We just need to limit it to the memory map limit, if any.
Okay. Let me try.
>
> But his function below looks really like a hack. If at all, it should
> be
> part of the get_ram_size() routine itself, as this is not sunxi
> specific.
This hack is too immature to be a common hack, it just consider 4GiB as
3GiB,
so it's still a sunxi specific hack.
>
> Cheers,
> Andre.
>
>
>> Signed-off-by: Icenowy Zheng <icenowy at aosc.io>
>> ---
>> board/sunxi/board.c | 23 +++++++++++++++++++++++
>> include/configs/sunxi-common.h | 2 +-
>> 2 files changed, 24 insertions(+), 1 deletion(-)
>>
>> diff --git a/board/sunxi/board.c b/board/sunxi/board.c
>> index 8891961dcc..8d707cbac2 100644
>> --- a/board/sunxi/board.c
>> +++ b/board/sunxi/board.c
>> @@ -256,7 +256,30 @@ int board_init(void)
>>
>> int dram_init(void)
>> {
>> +#if PHYS_SDRAM_0_SIZE == (SZ_2G + SZ_1G)
>> + /*
>> + * get_ram_size() doesn't support non-pow-of-2 sizes, so the
>> detection
>> + * of 3GiB DRAM is implemented here.
>> + * It just checks whether the DRAM is bigger than 2GiB, as the DRAM
>> + * module is usually 4GiB in this case (and 1GiB is not accessible).
>> + */
>> + u32 save_0, save_2g;
>> + gd->ram_size = get_ram_size((long *)PHYS_SDRAM_0, SZ_2G);
>> + if (gd->ram_size == SZ_2G) {
>> + save_0 = readl(PHYS_SDRAM_0);
>> + save_2g = readl(PHYS_SDRAM_0 + SZ_2G);
>> + writel(0, PHYS_SDRAM_0);
>> + writel(0xaa55aa55, PHYS_SDRAM_0 + SZ_2G);
>> + dsb();
>> + if (readl(PHYS_SDRAM_0) != readl(PHYS_SDRAM_0 + SZ_2G)) {
>> + gd->ram_size = SZ_2G + SZ_1G;
>> + writel(save_2g, PHYS_SDRAM_0 + SZ_2G);
>> + }
>> + writel(save_0, PHYS_SDRAM_0);
>> + }
>> +#else
>> gd->ram_size = get_ram_size((long *)PHYS_SDRAM_0,
>> PHYS_SDRAM_0_SIZE);
>> +#endif
>>
>> return 0;
>> }
>> diff --git a/include/configs/sunxi-common.h
>> b/include/configs/sunxi-common.h
>> index 9b3944ad13..177647e009 100644
>> --- a/include/configs/sunxi-common.h
>> +++ b/include/configs/sunxi-common.h
>> @@ -111,7 +111,7 @@
>>
>> #define CONFIG_NR_DRAM_BANKS 1
>> #define PHYS_SDRAM_0 CONFIG_SYS_SDRAM_BASE
>> -#define PHYS_SDRAM_0_SIZE 0x80000000 /* 2 GiB */
>> +#define PHYS_SDRAM_0_SIZE CONFIG_SUNXI_DRAM_MAX_SIZE
>>
>> #ifdef CONFIG_AHCI
>> #define CONFIG_SCSI_AHCI_PLAT
>>
More information about the U-Boot
mailing list