From 36b5d460261f16563f9196c49c936b3e17d237e3 Mon Sep 17 00:00:00 2001 From: Brian Norris Date: Mon, 20 Jun 2016 10:56:42 -0700 Subject: phy: rockchip-emmc: configure default output tap delay The output tap delay controls helps maintain the hold requirements for eMMC. The exact value is dependent on the SoC and other factors, though it isn't really an exact science. But the default of 0 is not very good, as it doesn't give the eMMC much hold time, so let's bump up to 4 (approx 90 degree phase?). If we need to configure this any further (e.g., based on board or speed factors), we may need to consider a device tree representation. Suggested-by: Shawn Lin Signed-off-by: Brian Norris Signed-off-by: Douglas Anderson Acked-by: Kishon Vijay Abraham I Tested-by: Heiko Stuebner Signed-off-by: Ulf Hansson --- drivers/phy/phy-rockchip-emmc.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) (limited to 'drivers/phy') diff --git a/drivers/phy/phy-rockchip-emmc.c b/drivers/phy/phy-rockchip-emmc.c index f2f75cf69af1..a0b87cc6c818 100644 --- a/drivers/phy/phy-rockchip-emmc.c +++ b/drivers/phy/phy-rockchip-emmc.c @@ -69,6 +69,11 @@ #define PHYCTRL_DR_66OHM 0x2 #define PHYCTRL_DR_100OHM 0x3 #define PHYCTRL_DR_40OHM 0x4 +#define PHYCTRL_OTAPDLYENA 0x1 +#define PHYCTRL_OTAPDLYENA_MASK 0x1 +#define PHYCTRL_OTAPDLYENA_SHIFT 0xb +#define PHYCTRL_OTAPDLYSEL_MASK 0xf +#define PHYCTRL_OTAPDLYSEL_SHIFT 0x7 struct rockchip_emmc_phy { unsigned int reg_offset; @@ -181,6 +186,20 @@ static int rockchip_emmc_phy_power_on(struct phy *phy) 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 */ ret = rockchip_emmc_phy_power(rk_phy, PHYCTRL_PDB_PWR_ON); if (ret) -- cgit v1.2.3