Re: [PATCH 02/14] phy: allwinner: phy-sun6i-mipi-dphy: Support D-PHY Rx mode for MIPI CSI-2

Helen Koike
2020-10-30T22:45:06Z

Hello,

On 10/23/20 2:45 PM, Paul Kocialkowski wrote:
> The Allwinner A31 D-PHY supports both Rx and Tx modes. While the latter
> is already supported and used for MIPI DSI this adds support for the
> former, to be used with MIPI CSI-2.
>
> This implementation is inspired by the Allwinner BSP implementation.
>
> Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
> ---
> drivers/phy/allwinner/phy-sun6i-mipi-dphy.c | 164 +++++++++++++++++++-
> 1 file changed, 160 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/phy/allwinner/phy-sun6i-mipi-dphy.c b/drivers/phy/allwinner/phy-sun6i-mipi-dphy.c
> index 1fa761ba6cbb..8bcd4bb79f60 100644
> --- a/drivers/phy/allwinner/phy-sun6i-mipi-dphy.c
> +++ b/drivers/phy/allwinner/phy-sun6i-mipi-dphy.c
> @@ -24,6 +24,14 @@
> #define SUN6I_DPHY_TX_CTL_REG 0x04
> #define SUN6I_DPHY_TX_CTL_HS_TX_CLK_CONT BIT(28)
>
> +#define SUN6I_DPHY_RX_CTL_REG 0x08
> +#define SUN6I_DPHY_RX_CTL_EN_DBC BIT(31)
> +#define SUN6I_DPHY_RX_CTL_RX_CLK_FORCE BIT(24)
> +#define SUN6I_DPHY_RX_CTL_RX_D3_FORCE BIT(23)
> +#define SUN6I_DPHY_RX_CTL_RX_D2_FORCE BIT(22)
> +#define SUN6I_DPHY_RX_CTL_RX_D1_FORCE BIT(21)
> +#define SUN6I_DPHY_RX_CTL_RX_D0_FORCE BIT(20)
> +
> #define SUN6I_DPHY_TX_TIME0_REG 0x10
> #define SUN6I_DPHY_TX_TIME0_HS_TRAIL(n) (((n) & 0xff) << 24)
> #define SUN6I_DPHY_TX_TIME0_HS_PREPARE(n) (((n) & 0xff) << 16)
> @@ -44,12 +52,29 @@
> #define SUN6I_DPHY_TX_TIME4_HS_TX_ANA1(n) (((n) & 0xff) << 8)
> #define SUN6I_DPHY_TX_TIME4_HS_TX_ANA0(n) ((n) & 0xff)
>
> +#define SUN6I_DPHY_RX_TIME0_REG 0x30
> +#define SUN6I_DPHY_RX_TIME0_HS_RX_SYNC(n) (((n) & 0xff) << 24)
> +#define SUN6I_DPHY_RX_TIME0_HS_RX_CLK_MISS(n) (((n) & 0xff) << 16)
> +#define SUN6I_DPHY_RX_TIME0_LP_RX(n) (((n) & 0xff) << 8)
> +
> +#define SUN6I_DPHY_RX_TIME1_REG 0x34
> +#define SUN6I_DPHY_RX_TIME1_RX_DLY(n) (((n) & 0xfff) << 20)
> +#define SUN6I_DPHY_RX_TIME1_LP_RX_ULPS_WP(n) ((n) & 0xfffff)
> +
> +#define SUN6I_DPHY_RX_TIME2_REG 0x38
> +#define SUN6I_DPHY_RX_TIME2_HS_RX_ANA1(n) (((n) & 0xff) << 8)
> +#define SUN6I_DPHY_RX_TIME2_HS_RX_ANA0(n) ((n) & 0xff)
> +
> +#define SUN6I_DPHY_RX_TIME3_REG 0x40
> +#define SUN6I_DPHY_RX_TIME3_LPRST_DLY(n) (((n) & 0xffff) << 16)
> +
> #define SUN6I_DPHY_ANA0_REG 0x4c
> #define SUN6I_DPHY_ANA0_REG_PWS BIT(31)
> #define SUN6I_DPHY_ANA0_REG_DMPC BIT(28)
> #define SUN6I_DPHY_ANA0_REG_DMPD(n) (((n) & 0xf) << 24)
> #define SUN6I_DPHY_ANA0_REG_SLV(n) (((n) & 7) << 12)
> #define SUN6I_DPHY_ANA0_REG_DEN(n) (((n) & 0xf) << 8)
> +#define SUN6I_DPHY_ANA0_REG_SFB(n) (((n) & 3) << 2)
>
> #define SUN6I_DPHY_ANA1_REG 0x50
> #define SUN6I_DPHY_ANA1_REG_VTTMODE BIT(31)
> @@ -92,6 +117,8 @@ struct sun6i_dphy {
>
> struct phy *phy;
> struct phy_configure_opts_mipi_dphy config;
> +
> + int submode;
> };
>
> static int sun6i_dphy_init(struct phy *phy)
> @@ -105,6 +132,18 @@ static int sun6i_dphy_init(struct phy *phy)
> return 0;
> }
>
> +static int sun6i_dphy_set_mode(struct phy *phy, enum phy_mode mode, int submode)
> +{
> + struct sun6i_dphy *dphy = phy_get_drvdata(phy);
> +
> + if (mode != PHY_MODE_MIPI_DPHY)
> + return -EINVAL;
> +
> + dphy->submode = submode;

Shouldn't you check if the submode is valid here?

> +
> + return 0;
> +}
> +
> static int sun6i_dphy_configure(struct phy *phy, union phy_configure_opts *opts)
> {
> struct sun6i_dphy *dphy = phy_get_drvdata(phy);
> @@ -119,9 +158,8 @@ static int sun6i_dphy_configure(struct phy *phy, union phy_configure_opts *opts)
> return 0;
> }
>
> -static int sun6i_dphy_power_on(struct phy *phy)
> +static int sun6i_dphy_tx_power_on(struct sun6i_dphy *dphy)
> {
> - struct sun6i_dphy *dphy = phy_get_drvdata(phy);
> u8 lanes_mask = GENMASK(dphy->config.lanes - 1, 0);
>
> regmap_write(dphy->regs, SUN6I_DPHY_TX_CTL_REG,
> @@ -211,12 +249,129 @@ static int sun6i_dphy_power_on(struct phy *phy)
> return 0;
> }
>
> +static int sun6i_dphy_rx_power_on(struct sun6i_dphy *dphy)
> +{
> + /* Physical clock rate is actually half of symbol rate with DDR. */
> + unsigned long mipi_symbol_rate = dphy->config.hs_clk_rate;
> + unsigned long dphy_clk_rate;
> + unsigned int rx_dly;
> + unsigned int lprst_dly;
> + u32 value;
> +
> + dphy_clk_rate = clk_get_rate(dphy->mod_clk);
> + if (!dphy_clk_rate)
> + return -1;
> +
> + /* Hardcoded timing parameters from the Allwinner BSP. */
> + regmap_write(dphy->regs, SUN6I_DPHY_RX_TIME0_REG,
> + SUN6I_DPHY_RX_TIME0_HS_RX_SYNC(255) |
> + SUN6I_DPHY_RX_TIME0_HS_RX_CLK_MISS(255) |
> + SUN6I_DPHY_RX_TIME0_LP_RX(255));
> +
> + /*
> + * Formula from the Allwinner BSP, with hardcoded coefficients
> + * (probably internal divider/multiplier).
> + */
> + rx_dly = 8 * (unsigned int)(dphy_clk_rate / (mipi_symbol_rate / 8));
> +
> + /*
> + * The Allwinner BSP has an alternative formula for LP_RX_ULPS_WP:
> + * lp_ulps_wp_cnt = lp_ulps_wp_ms * lp_clk / 1000
> + * but does not use it and hardcodes 255 instead.
> + */
> + regmap_write(dphy->regs, SUN6I_DPHY_RX_TIME1_REG,
> + SUN6I_DPHY_RX_TIME1_RX_DLY(rx_dly) |
> + SUN6I_DPHY_RX_TIME1_LP_RX_ULPS_WP(255));
> +
> + /* HS_RX_ANA0 value is hardcoded in the Allwinner BSP. */
> + regmap_write(dphy->regs, SUN6I_DPHY_RX_TIME2_REG,
> + SUN6I_DPHY_RX_TIME2_HS_RX_ANA0(4));
> +
> + /*
> + * Formula from the Allwinner BSP, with hardcoded coefficients
> + * (probably internal divider/multiplier).
> + */
> + lprst_dly = 4 * (unsigned int)(dphy_clk_rate / (mipi_symbol_rate / 2));
> +
> + regmap_write(dphy->regs, SUN6I_DPHY_RX_TIME3_REG,
> + SUN6I_DPHY_RX_TIME3_LPRST_DLY(lprst_dly));
> +
> + /* Analog parameters are hardcoded in the Allwinner BSP. */
> + regmap_write(dphy->regs, SUN6I_DPHY_ANA0_REG,
> + SUN6I_DPHY_ANA0_REG_PWS |
> + SUN6I_DPHY_ANA0_REG_SLV(7) |
> + SUN6I_DPHY_ANA0_REG_SFB(2));
> +
> + regmap_write(dphy->regs, SUN6I_DPHY_ANA1_REG,
> + SUN6I_DPHY_ANA1_REG_SVTT(4));
> +
> + regmap_write(dphy->regs, SUN6I_DPHY_ANA4_REG,
> + SUN6I_DPHY_ANA4_REG_DMPLVC |
> + SUN6I_DPHY_ANA4_REG_DMPLVD(1));
> +
> + regmap_write(dphy->regs, SUN6I_DPHY_ANA2_REG,
> + SUN6I_DPHY_ANA2_REG_ENIB);
> +
> + regmap_write(dphy->regs, SUN6I_DPHY_ANA3_REG,
> + SUN6I_DPHY_ANA3_EN_LDOR |
> + SUN6I_DPHY_ANA3_EN_LDOC |
> + SUN6I_DPHY_ANA3_EN_LDOD);
> +
> + /*
> + * Delay comes from the Allwinner BSP, likely for internal regulator
> + * ramp-up.
> + */
> + udelay(3);
> +
> + value = SUN6I_DPHY_RX_CTL_EN_DBC | SUN6I_DPHY_RX_CTL_RX_CLK_FORCE;
> +
> + /*
> + * Rx data lane force-enable bits are used as regular RX enable by the
> + * Allwinner BSP.
> + */
> + if (dphy->config.lanes >= 1)
> + value |= SUN6I_DPHY_RX_CTL_RX_D0_FORCE;
> + if (dphy->config.lanes >= 2)
> + value |= SUN6I_DPHY_RX_CTL_RX_D1_FORCE;
> + if (dphy->config.lanes >= 3)
> + value |= SUN6I_DPHY_RX_CTL_RX_D2_FORCE;
> + if (dphy->config.lanes == 4)
> + value |= SUN6I_DPHY_RX_CTL_RX_D3_FORCE;

I would replace this by a switch case with fallthrough to avoid too many comparisons
to the same value.

Regards,
Helen

> +
> + regmap_write(dphy->regs, SUN6I_DPHY_RX_CTL_REG, value);
> +
> + regmap_write(dphy->regs, SUN6I_DPHY_GCTL_REG,
> + SUN6I_DPHY_GCTL_LANE_NUM(dphy->config.lanes) |
> + SUN6I_DPHY_GCTL_EN);
> +
> + return 0;
> +}
> +
> +static int sun6i_dphy_power_on(struct phy *phy)
> +{
> + struct sun6i_dphy *dphy = phy_get_drvdata(phy);
> +
> + switch (dphy->submode) {
> + case PHY_MIPI_DPHY_SUBMODE_TX:
> + return sun6i_dphy_tx_power_on(dphy);
> + case PHY_MIPI_DPHY_SUBMODE_RX:
> + return sun6i_dphy_rx_power_on(dphy);
> + default:
> + return -EINVAL;
> + }
> +}
> +
> static int sun6i_dphy_power_off(struct phy *phy)
> {
> struct sun6i_dphy *dphy = phy_get_drvdata(phy);
>
> - regmap_update_bits(dphy->regs, SUN6I_DPHY_ANA1_REG,
> - SUN6I_DPHY_ANA1_REG_VTTMODE, 0);
> + regmap_write(dphy->regs, SUN6I_DPHY_GCTL_REG, 0);
> +
> + regmap_write(dphy->regs, SUN6I_DPHY_ANA0_REG, 0);
> + regmap_write(dphy->regs, SUN6I_DPHY_ANA1_REG, 0);
> + regmap_write(dphy->regs, SUN6I_DPHY_ANA2_REG, 0);
> + regmap_write(dphy->regs, SUN6I_DPHY_ANA3_REG, 0);
> + regmap_write(dphy->regs, SUN6I_DPHY_ANA4_REG, 0);
>
> return 0;
> }
> @@ -234,6 +389,7 @@ static int sun6i_dphy_exit(struct phy *phy)
>
>
> static const struct phy_ops sun6i_dphy_ops = {
> + .set_mode = sun6i_dphy_set_mode,
> .configure = sun6i_dphy_configure,
> .power_on = sun6i_dphy_power_on,
> .power_off = sun6i_dphy_power_off,
>