Hi Jack, On Fri, Apr 24, 2020 at 1:08 AM Jack Mitchell <m...@embed.me.uk> wrote: > > On 23/04/2020 12:38, Jagan Teki wrote: > > On Tue, Apr 21, 2020 at 7:54 PM Jack Mitchell <m...@embed.me.uk> wrote: > >> > >> Has anyone worked with an rk3399 based board with a single channel RAM > >> setup? I've looked at the current code and made some changes for only > >> setting up a single channel which basically consists of altering the > >> loops down to one channel, however u-boot is hanging while checking for > >> a successful frequency change here: > >> > >>> /* change freq */ > >>> writel((((0x3 << 4) | (1 << 2) | 1) << 16) | > >>> (fn << 4) | (1 << 2) | 1, &dram->cic->cic_ctrl0); > >>> while (!(readl(&dram->cic->cic_status0) & (1 << 2))) > >>> ; > >>> > >> > >> I believe this is due to waiting for both channels to switch frequency > >> which will never happen as there is only a single channel setup. > >> > >> Has anyone worked with a similar setup, or have any further > >> documentation as the TRM only has a fairly basic register listing. > > > > I have tried single-channel with DDR3 which is present on NOE4, I > > believe the existing code does handle single channel for LPDDR4, can > > you enable debugs and check on existing code. Usually the code cannot > > go and try channel 1. > > > > Jagan. > > > > Hi Jagen, > > So I've managed to confirm it working in single channel with DDR4 on a > Khadas Edge-V by shorting the reset line to RAM chip on the second > channel, u-boot successfully comes up while only detecting a single chip. > > We've compared our board design with the NEO4 and the biggest notable > difference we can see is that they power the second channel even though > it's unused, while in our design we don't, leaving it completely > disconnected. I believe this is what's causing our difficulties. Are you > aware of any workaround which instructs the SoC to completely ignore the > second channel?
I did try to check this any dram register to route SoC to inform about channeling, but unfortunately I couldn't find any relevenet. Maybe Kever, YouMin might help. Jagan.