Rockchip RK3399平台EMMC驱动能力修改方法

Rockchip RK3399平台EMMC驱动能力修改方法

RK3399 EMMC的驱动能力可以通过如下代码修改：

@sys2_206:~/1_Android11_sdk_29/kernel$ vim drivers/phy/rockchip/phy-rockchip-emmc.c
static int rockchip_emmc_phy_power_on(struct phy *phy)
{
        struct rockchip_emmc_phy *rk_phy = phy_get_drvdata(phy);

        /* Drive impedance: 50 Ohm */
        regmap_write(rk_phy->reg_base,
                     rk_phy->reg_offset + GRF_EMMCPHY_CON6,
                     HIWORD_UPDATE(PHYCTRL_DR_50OHM,
                                   PHYCTRL_DR_MASK,
                                   PHYCTRL_DR_SHIFT));

        /* Output tap delay: enable */
        regmap_write(rk_phy->reg_base,
                     rk_phy->reg_offset + GRF_EMMCPHY_CON0,
                     HIWORD_UPDATE(PHYCTRL_OTAPDLYENA,
                                   PHYCTRL_OTAPDLYENA_MASK,
                                   PHYCTRL_OTAPDLYENA_SHIFT));

        /* Output tap delay */
        regmap_write(rk_phy->reg_base,
                     rk_phy->reg_offset + GRF_EMMCPHY_CON0,
                     HIWORD_UPDATE(4,
                                   PHYCTRL_OTAPDLYSEL_MASK,
                                   PHYCTRL_OTAPDLYSEL_SHIFT));

        /* Power up emmc phy analog blocks */
        return rockchip_emmc_phy_power(phy, PHYCTRL_PDB_PWR_ON);
}

上面代码中的PHYCTRL_DR_50OHM可以根据实际需求改为下面的其他阻抗值：

 68 #define PHYCTRL_DR_50OHM                0x0
 69 #define PHYCTRL_DR_33OHM                0x1
 70 #define PHYCTRL_DR_66OHM                0x2
 71 #define PHYCTRL_DR_100OHM               0x3
 72 #define PHYCTRL_DR_40OHM                0x4

驱动阻抗越小驱动能力越大