On Thu, 11 Aug 2022 at 05:09, Lee Jones lee@kernel.org wrote:

Currently the default initialisation frequency is 50MHz. Although this does appear to be suitable for some LPDDR4 RAM chips, training at this low frequency has been seen to cause Column errors, leading to Capacity check errors on others.

Here we force RAM initialisation to happen at 400MHz before ramping up to the final value running value of 800MHz after everything has been successfully configured.

Link: https://lore.kernel.org/u-boot/Yo4v3jUeHXTovjOH@google.com/ Suggested-by: YouMin Chen cym@rock-chips.com Signed-off-by: Lee Jones lee@kernel.org Tested-by: Xavier Drudis Ferran xdrudis@tinet.cat Reviewed-by: Kever Yang kever.yang@rock-chips.com

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drivers/ram/rockchip/sdram_rk3399.c | 36 +++++++++++++++++------------ 1 file changed, 21 insertions(+), 15 deletions(-)

Reviewed-by: Simon Glass sjg@chromium.org