[U-Boot] [PATCH 3/3] rockchip: fix incorrect detection of ram size

[Dr. Philipp Tomsich]

> On 6 May 2018, at 16:25, Marty E. Plummer <hanetzer at startmail.com> wrote:
> 
> Taken from coreboot's src/soc/rockchip/rk3288/sdram.c
> 
> Without this change, my u-boot build for the asus c201 chromebook (4GiB)
> is incorrectly detected as 0 Bytes of ram.

Could you elaborate what the change is and what root-cause this addresses (4GB
reporting as 0 sounds a bit like a 32bit type overflowing)?
It’s really hard to tell from the patch below (which seems to have everything simply
reformatted to a different indentation)...

> 
> Signed-off-by: Marty E. Plummer <hanetzer at startmail.com>
> ---
> arch/arm/mach-rockchip/sdram_common.c | 62 ++++++++++++++++-----------
> 1 file changed, 37 insertions(+), 25 deletions(-)
> 
> diff --git a/arch/arm/mach-rockchip/sdram_common.c b/arch/arm/mach-rockchip/sdram_common.c
> index 76dbdc8715..a9c9f970a4 100644
> --- a/arch/arm/mach-rockchip/sdram_common.c
> +++ b/arch/arm/mach-rockchip/sdram_common.c
> @@ -10,6 +10,8 @@
> #include <asm/io.h>
> #include <asm/arch/sdram_common.h>
> #include <dm/uclass-internal.h>
> +#include <linux/kernel.h>
> +#include <linux/sizes.h>
> 
> DECLARE_GLOBAL_DATA_PTR;
> size_t rockchip_sdram_size(phys_addr_t reg)
> @@ -19,34 +21,44 @@ size_t rockchip_sdram_size(phys_addr_t reg)
> 	size_t size_mb = 0;
> 	u32 ch;
> 
> -	u32 sys_reg = readl(reg);
> -	u32 ch_num = 1 + ((sys_reg >> SYS_REG_NUM_CH_SHIFT)
> -		       & SYS_REG_NUM_CH_MASK);
> +	if (!size_mb) {

Given that there’s a “size_mb = 0” just above it, this will always evaluate
to true… 

> 
> -	debug("%s %x %x\n", __func__, (u32)reg, sys_reg);
> -	for (ch = 0; ch < ch_num; ch++) {
> -		rank = 1 + (sys_reg >> SYS_REG_RANK_SHIFT(ch) &
> -			SYS_REG_RANK_MASK);
> -		col = 9 + (sys_reg >> SYS_REG_COL_SHIFT(ch) & SYS_REG_COL_MASK);
> -		bk = 3 - ((sys_reg >> SYS_REG_BK_SHIFT(ch)) & SYS_REG_BK_MASK);
> -		cs0_row = 13 + (sys_reg >> SYS_REG_CS0_ROW_SHIFT(ch) &
> -				SYS_REG_CS0_ROW_MASK);
> -		cs1_row = 13 + (sys_reg >> SYS_REG_CS1_ROW_SHIFT(ch) &
> -				SYS_REG_CS1_ROW_MASK);
> -		bw = (2 >> ((sys_reg >> SYS_REG_BW_SHIFT(ch)) &
> -			SYS_REG_BW_MASK));
> -		row_3_4 = sys_reg >> SYS_REG_ROW_3_4_SHIFT(ch) &
> -			SYS_REG_ROW_3_4_MASK;
> +		u32 sys_reg = readl(reg);
> +		u32 ch_num = 1 + ((sys_reg >> SYS_REG_NUM_CH_SHIFT)
> +			       & SYS_REG_NUM_CH_MASK);
> 
> -		chipsize_mb = (1 << (cs0_row + col + bk + bw - 20));
> +		debug("%s %x %x\n", __func__, (u32)reg, sys_reg);
> +		for (ch = 0; ch < ch_num; ch++) {
> +			rank = 1 + (sys_reg >> SYS_REG_RANK_SHIFT(ch) &
> +				SYS_REG_RANK_MASK);
> +			col = 9 + (sys_reg >> SYS_REG_COL_SHIFT(ch) & SYS_REG_COL_MASK);
> +			bk = 3 - ((sys_reg >> SYS_REG_BK_SHIFT(ch)) & SYS_REG_BK_MASK);
> +			cs0_row = 13 + (sys_reg >> SYS_REG_CS0_ROW_SHIFT(ch) &
> +					SYS_REG_CS0_ROW_MASK);
> +			cs1_row = 13 + (sys_reg >> SYS_REG_CS1_ROW_SHIFT(ch) &
> +					SYS_REG_CS1_ROW_MASK);
> +			bw = (2 >> ((sys_reg >> SYS_REG_BW_SHIFT(ch)) &
> +				SYS_REG_BW_MASK));
> +			row_3_4 = sys_reg >> SYS_REG_ROW_3_4_SHIFT(ch) &
> +				SYS_REG_ROW_3_4_MASK;
> 
> -		if (rank > 1)
> -			chipsize_mb += chipsize_mb >> (cs0_row - cs1_row);
> -		if (row_3_4)
> -			chipsize_mb = chipsize_mb * 3 / 4;
> -		size_mb += chipsize_mb;
> -		debug("rank %d col %d bk %d cs0_row %d bw %d row_3_4 %d\n",
> -		      rank, col, bk, cs0_row, bw, row_3_4);
> +			chipsize_mb = (1 << (cs0_row + col + bk + bw - 20));
> +
> +			if (rank > 1)
> +				chipsize_mb += chipsize_mb >> (cs0_row - cs1_row);
> +			if (row_3_4)
> +				chipsize_mb = chipsize_mb * 3 / 4;
> +			size_mb += chipsize_mb;
> +			debug("rank %d col %d bk %d cs0_row %d bw %d row_3_4 %d\n",
> +			      rank, col, bk, cs0_row, bw, row_3_4);
> +		}
> +
> +		/*
> +		 * we use the 0x00000000~0xfeffffff space
> +		 * since 0xff000000~0xffffffff is soc register space
> +		 * so we reserve it
> +		 */
> +		size_mb = min(size_mb, 0xff000000/SZ_1M);
> 	}
> 
> 	return (size_t)size_mb << 20;
> -- 
> 2.17.0
> 
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