From c453a80cc3b999ad515ed7fcfcf3062e8de1f696 Mon Sep 17 00:00:00 2001 From: Andre Przywara Date: Sun, 27 Jul 2025 14:04:09 +0100 Subject: [PATCH] sunxi: H616: dram: fix LPDDR3 mode register settings The JEDEC LPDDR3 spec defines mode register 0 (MR0) as being read-only, so there is no point in trying to set its value. Also the H616 memory controller encodes the mode register index to be written starting from bit 8 in MRCTRL1 (for LPDDR3 and LPDDR4 chips), so we need to OR in that number to tell the controller which MR to program. On top of that, the mode registers between DDR3 and LPDDR3 are completely different, so writing values crafted for DDR3 into a LPDDR3 chip is just wrong. Due to the above mentioned bugs the writes for MR0-MR2 did not have any effect (as they were all trying to set the read-only MR0), so the mode registers just stayed unchanged. Looking at the LPDDR3 spec and the BSP code, let's write the proper MR values into LPDDR3 chips, using the proper addressing mode. Use the opportunity to document the LPDDR3 mode register bits written. Signed-off-by: Andre Przywara Reviewed-by: Jernej Skrabec --- arch/arm/mach-sunxi/dram_sun50i_h616.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/arch/arm/mach-sunxi/dram_sun50i_h616.c b/arch/arm/mach-sunxi/dram_sun50i_h616.c index 877181016f3..3345c9b8e82 100644 --- a/arch/arm/mach-sunxi/dram_sun50i_h616.c +++ b/arch/arm/mach-sunxi/dram_sun50i_h616.c @@ -1078,18 +1078,18 @@ static bool mctl_phy_init(const struct dram_para *para, mctl_await_completion(&mctl_ctl->mrctrl0, BIT(31), 0); break; case SUNXI_DRAM_TYPE_LPDDR3: - writel(mr0, &mctl_ctl->mrctrl1); - writel(0x800000f0, &mctl_ctl->mrctrl0); - mctl_await_completion(&mctl_ctl->mrctrl0, BIT(31), 0); - - writel(4, &mctl_ctl->mrctrl1); + /* MR0 is read-only */ + /* MR1: nWR=14, BL8 */ + writel(0x183, &mctl_ctl->mrctrl1); writel(0x800000f0, &mctl_ctl->mrctrl0); mctl_await_completion(&mctl_ctl->mrctrl0, BIT(31), 0); - writel(mr2, &mctl_ctl->mrctrl1); + /* MR2: no WR leveling, WL set A, use nWR>9, nRL=14/nWL=8 */ + writel(0x21c, &mctl_ctl->mrctrl1); writel(0x800000f0, &mctl_ctl->mrctrl0); mctl_await_completion(&mctl_ctl->mrctrl0, BIT(31), 0); + /* MR3: 34.3 Ohm pull-up/pull-down resistor */ writel(0x301, &mctl_ctl->mrctrl1); writel(0x800000f0, &mctl_ctl->mrctrl0); mctl_await_completion(&mctl_ctl->mrctrl0, BIT(31), 0); -- 2.47.2