sunxi: fix DRAM gate/reset sequence of H6

Currently the DRAM bus gate and reset is changed at the same time in
H6 DRAM initialization code, which disobeys the user manual's
programming guide.

Fix the sequence by follow the sequence suggested by the user manual
(ungate the bus clock after release the reset signal).

By some experiments it seems to fix the DRAM size detection failure that
rarely happens.

Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
Acked-by: Maxime Ripard <maxime.ripard@bootlin.com>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>

diff --git a/arch/arm/mach-sunxi/dram_sun50i_h6.c b/arch/arm/mach-sunxi/dram_sun50i_h6.c
index 6b94cf38c5c86dd50e2699748fc05e846494b6de..5da90a2835da02af177fed1916f55dd4f9ae786c 100644 (file)
--- a/arch/arm/mach-sunxi/dram_sun50i_h6.c
+++ b/arch/arm/mach-sunxi/dram_sun50i_h6.c
@@ -299,6 +299,8 @@ static void mctl_sys_init(struct dram_para *para)
 
        /* Put all DRAM-related blocks to reset state */
        clrbits_le32(&ccm->mbus_cfg, MBUS_ENABLE | MBUS_RESET);
+       clrbits_le32(&ccm->dram_gate_reset, BIT(0));
+       udelay(5);
        writel(0, &ccm->dram_gate_reset);
        clrbits_le32(&ccm->pll5_cfg, CCM_PLL5_CTRL_EN);
        clrbits_le32(&ccm->dram_clk_cfg, DRAM_MOD_RESET);
@@ -313,7 +315,9 @@ static void mctl_sys_init(struct dram_para *para)
        /* Configure DRAM mod clock */
        writel(DRAM_CLK_SRC_PLL5, &ccm->dram_clk_cfg);
        setbits_le32(&ccm->dram_clk_cfg, DRAM_CLK_UPDATE);
-       writel(BIT(0) | BIT(RESET_SHIFT), &ccm->dram_gate_reset);
+       writel(BIT(RESET_SHIFT), &ccm->dram_gate_reset);
+       udelay(5);
+       setbits_le32(&ccm->dram_gate_reset, BIT(0));
 
        /* Disable all channels */
        writel(0, &mctl_com->maer0);