> Subject: Re: [PATCH 2/2] imx: Support i.MX91 11x11 FRDM board > > Hi Peng, > > On Mon, Dec 1, 2025 at 11:36 PM Peng Fan <[email protected]> > wrote: > > > With ECC enabled, some DRAM space needs to be reserved to store > ECC. > > With ECC disabled, no need to reserve DRAM space for ECC area. > > Thanks for the clarification. How large does the ECC area need to be?
It is auto calculated by reading the DDR settings, for 2GB DRAM, it
is about 128MB? I could not recall clearly.
__weak int board_phys_sdram_size(phys_size_t *size)
{
phys_size_t start, end;
phys_size_t val;
if (!size)
return -EINVAL;
val = readl(REG_DDR_CS0_BNDS);
start = (val >> 16) << 24;
end = (val & 0xFFFF);
end = end ? end + 1 : 0;
end = end << 24;
*size = end - start;
val = readl(REG_DDR_CS1_BNDS);
start = (val >> 16) << 24;
end = (val & 0xFFFF);
end = end ? end + 1 : 0;
end = end << 24;
*size += end - start;
return 0;
Regards
Peng.
>
> Joseph,
>
> Please add this explanation to the board's README to help users select
> the more appropriate defconfig for their use case.
>
> Thank
