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 <[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
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
