On Tue, Dec 02, 2025 at 03:36:13AM +0000, Peng Fan wrote:
> > 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 <peng.fan at nxp.com>
> > 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
Hi Fabio,
ECC will reduce 1/8 ddr size. In i.MX91 FRDM,
The ddr size reduce from 1024M to 896M. Sure I will add this explanation
to README. Thanks.
Regards,
Joseph