Re: [PATCH 4/4] phy: freescale: phy-fsl-imx8-mipi-dphy: Add i.MX8qxp LVDS PHY mode support

From: Liu Ying
Date: Thu Dec 10 2020 - 04:00:03 EST

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In reply to: Guido Günther: "Re: [PATCH 4/4] phy: freescale: phy-fsl-imx8-mipi-dphy: Add i.MX8qxp LVDS PHY mode support"
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Hi Guido,

On Thu, 2020-12-10 at 08:14 +0100, Guido Günther wrote:
> Hi,
> On Tue, Dec 08, 2020 at 06:03:05PM +0800, Liu Ying wrote:
> > On Tue, 2020-12-08 at 10:24 +0100, Guido Günther wrote:
> > > Hi Liu,
> > > some minor comments inline:
> > >
> > > On Fri, Dec 04, 2020 at 03:33:44PM +0800, Liu Ying wrote:
> > > > i.MX8qxp SoC embeds a Mixel MIPI DPHY + LVDS PHY combo which supports
> > > > either a MIPI DSI display or a LVDS display. The PHY mode is controlled
> > > > by SCU firmware and the driver would call a SCU firmware function to
> > > > configure the PHY mode. The single LVDS PHY has 4 data lanes to support
> > > > a LVDS display. Also, with a master LVDS PHY and a slave LVDS PHY, they
> > > > may work together to support a LVDS display with 8 data lanes(usually, dual
> > > > LVDS link display). Note that this patch supports the LVDS PHY mode only
> > > > for the i.MX8qxp Mixel combo PHY, i.e., the MIPI DPHY mode is yet to be
> > > > supported, so for now error would be returned from ->set_mode() if MIPI
> > > > DPHY mode is passed over to it for the combo PHY.
> > > >
> > > > Cc: Guido Günther <agx@xxxxxxxxxxx>
> > > > Cc: Robert Chiras <robert.chiras@xxxxxxx>
> > > > Cc: Kishon Vijay Abraham I <kishon@xxxxxx>
> > > > Cc: Vinod Koul <vkoul@xxxxxxxxxx>
> > > > Cc: Shawn Guo <shawnguo@xxxxxxxxxx>
> > > > Cc: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
> > > > Cc: Pengutronix Kernel Team <kernel@xxxxxxxxxxxxxx>
> > > > Cc: Fabio Estevam <festevam@xxxxxxxxx>
> > > > Cc: NXP Linux Team <linux-imx@xxxxxxx>
> > > > Signed-off-by: Liu Ying <victor.liu@xxxxxxx>
> > > > ---
> > > > drivers/phy/freescale/phy-fsl-imx8-mipi-dphy.c | 266 ++++++++++++++++++++++++-
> > > > 1 file changed, 255 insertions(+), 11 deletions(-)
> > > >
> > > > diff --git a/drivers/phy/freescale/phy-fsl-imx8-mipi-dphy.c b/drivers/phy/freescale/phy-fsl-imx8-mipi-dphy.c
> > > > index a95572b..37084a9 100644
> > > > --- a/drivers/phy/freescale/phy-fsl-imx8-mipi-dphy.c
> > > > +++ b/drivers/phy/freescale/phy-fsl-imx8-mipi-dphy.c
> > > > @@ -4,17 +4,31 @@
> > > > * Copyright 2019 Purism SPC
> > > > */
> > > >
> > > > +#include <linux/bitfield.h>
> > > > #include <linux/clk.h>
> > > > #include <linux/clk-provider.h>
> > > > #include <linux/delay.h>
> > > > +#include <linux/firmware/imx/ipc.h>
> > > > +#include <linux/firmware/imx/svc/misc.h>
> > > > #include <linux/io.h>
> > > > #include <linux/kernel.h>
> > > > +#include <linux/mfd/syscon.h>
> > > > #include <linux/module.h>
> > > > #include <linux/of.h>
> > > > #include <linux/of_platform.h>
> > > > #include <linux/phy/phy.h>
> > > > #include <linux/platform_device.h>
> > > > #include <linux/regmap.h>
> > > > +#include <dt-bindings/firmware/imx/rsrc.h>
> > > > +
> > > > +/* Control and Status Registers(CSR) */
> > > > +#define PHY_CTRL 0x00
> > > > +#define CCM_MASK GENMASK(7, 5)
> > > > +#define CCM(n) FIELD_PREP(CCM_MASK, (n))
> > > > +#define CA_MASK GENMASK(4, 2)
> > > > +#define CA(n) FIELD_PREP(CA_MASK, (n))
> > > > +#define RFB BIT(1)
> > > > +#define LVDS_EN BIT(0)
> > > >
> > > > /* DPHY registers */
> > > > #define DPHY_PD_DPHY 0x00
> > > > @@ -55,8 +69,15 @@
> > > > #define PWR_ON 0
> > > > #define PWR_OFF 1
> > > >
> > > > +#define MIN_VCO_FREQ 640000000
> > > > +#define MAX_VCO_FREQ 1500000000
> > > > +
> > > > +#define MIN_LVDS_REFCLK_FREQ 24000000
> > > > +#define MAX_LVDS_REFCLK_FREQ 150000000
> > > > +
> > > > enum mixel_dphy_devtype {
> > > > MIXEL_IMX8MQ,
> > > > + MIXEL_IMX8QXP,
> > > > };
> > > >
> > > > struct mixel_dphy_devdata {
> > > > @@ -65,6 +86,7 @@ struct mixel_dphy_devdata {
> > > > u8 reg_rxlprp;
> > > > u8 reg_rxcdrp;
> > > > u8 reg_rxhs_settle;
> > > > + bool is_combo; /* MIPI DPHY and LVDS PHY combo */
> > > > };
> > > >
> > > > static const struct mixel_dphy_devdata mixel_dphy_devdata[] = {
> > > > @@ -74,6 +96,10 @@ static const struct mixel_dphy_devdata mixel_dphy_devdata[] = {
> > > > .reg_rxlprp = 0x40,
> > > > .reg_rxcdrp = 0x44,
> > > > .reg_rxhs_settle = 0x48,
> > > > + .is_combo = false,
> > > > + },
> > > > + [MIXEL_IMX8QXP] = {
> > > > + .is_combo = true,
> > > > },
> > > > };
> > > >
> > > > @@ -95,8 +121,12 @@ struct mixel_dphy_cfg {
> > > > struct mixel_dphy_priv {
> > > > struct mixel_dphy_cfg cfg;
> > > > struct regmap *regmap;
> > > > + struct regmap *lvds_regmap;
> > > > struct clk *phy_ref_clk;
> > > > const struct mixel_dphy_devdata *devdata;
> > > > + struct imx_sc_ipc *ipc_handle;
> > > > + bool is_slave;
> > > > + int id;
> > > > };
> > > >
> > > > static const struct regmap_config mixel_dphy_regmap_config = {
> > > > @@ -317,7 +347,8 @@ static int mixel_dphy_set_pll_params(struct phy *phy)
> > > > return 0;
> > > > }
> > > >
> > > > -static int mixel_dphy_configure(struct phy *phy, union phy_configure_opts *opts)
> > > > +static int
> > > > +mixel_dphy_configure_mipi_dphy(struct phy *phy, union phy_configure_opts *opts)
> > > > {
> > > > struct mixel_dphy_priv *priv = phy_get_drvdata(phy);
> > > > struct mixel_dphy_cfg cfg = { 0 };
> > > > @@ -345,15 +376,118 @@ static int mixel_dphy_configure(struct phy *phy, union phy_configure_opts *opts)
> > > > return 0;
> > > > }
> > > >
> > > > +static int
> > > > +mixel_dphy_configure_lvds_phy(struct phy *phy, union phy_configure_opts *opts)
> > > > +{
> > > > + struct mixel_dphy_priv *priv = phy_get_drvdata(phy);
> > > > + struct phy_configure_opts_lvds *lvds_opts = &opts->lvds;
> > > > + unsigned long data_rate;
> > > > + unsigned long fvco;
> > > > + u32 rsc;
> > > > + u32 co;
> > > > + int ret;
> > > > +
> > > > + priv->is_slave = lvds_opts->is_slave;
> > > > +
> > > > + /* LVDS interface pins */
> > > > + regmap_write(priv->lvds_regmap, PHY_CTRL, CCM(0x5) | CA(0x4) | RFB);
> > > > +
> > > > + /* enable MODE8 only for slave LVDS PHY */
> > > > + rsc = priv->id ? IMX_SC_R_MIPI_1 : IMX_SC_R_MIPI_0;
> > > > + ret = imx_sc_misc_set_control(priv->ipc_handle, rsc, IMX_SC_C_DUAL_MODE,
> > > > + lvds_opts->is_slave);
> > > > + if (ret) {
> > > > + dev_err(&phy->dev, "Failed to configure MODE8: %d\n", ret);
> > > > + return ret;
> > > > + }
> > > > +
> > > > + /*
> > > > + * Choose an appropriate divider ratio to meet the requirement of
> > > > + * PLL VCO frequency range.
> > > > + *
> > > > + * ----- 640MHz ~ 1500MHz ------------ ---------------
> > > > + * | VCO | ----------------> | CO divider | -> | LVDS data rate|
> > > > + * ----- FVCO ------------ ---------------
> > > > + * 1/2/4/8 div 7 * differential_clk_rate
> > > > + */
> > > > + data_rate = 7 * lvds_opts->differential_clk_rate;
> > > > + for (co = 1; co <= 8; co *= 2) {
> > > > + fvco = data_rate * co;
> > > > +
> > > > + if (fvco >= MIN_VCO_FREQ)
> > > > + break;
> > > > + }
> > > > +
> > > > + if (fvco < MIN_VCO_FREQ || fvco > MAX_VCO_FREQ) {
> > > > + dev_err(&phy->dev, "VCO frequency %lu is out of range\n", fvco);
> > > > + return -ERANGE;
> > > > + }
> > > > +
> > > > + /*
> > > > + * CO is configurable, while CN and CM are not,
> > > > + * as fixed ratios 1 and 7 are applied respectively.
> > > > + */
> > > > + phy_write(phy, __ffs(co), DPHY_CO);
> > > > +
> > > > + /* set reference clock rate */
> > > > + clk_set_rate(priv->phy_ref_clk, lvds_opts->differential_clk_rate);
> > > > +
> > > > + return ret;
> > > > +}
> > > > +
> > > > +static int mixel_dphy_configure(struct phy *phy, union phy_configure_opts *opts)
> > > > +{
> > > > + if (phy->attrs.mode == PHY_MODE_MIPI_DPHY)
> > > > + return mixel_dphy_configure_mipi_dphy(phy, opts);
> > > > + else if (phy->attrs.mode == PHY_MODE_LVDS)
> > > > + return mixel_dphy_configure_lvds_phy(phy, opts);
> > > > +
> > > > + dev_err(&phy->dev, "Failed to configure PHY with invalid PHY mode\n");
> > > > + return -EINVAL;
> > > > +}
> > > > +
> > > > +static int
> > > > +mixel_dphy_validate_lvds_phy(struct phy *phy, union phy_configure_opts *opts)
> > > > +{
> > > > + struct phy_configure_opts_lvds *lvds_cfg = &opts->lvds;
> > > > +
> > > > + if (lvds_cfg->bits_per_lane_and_dclk_cycle != 7) {
> > > > + dev_err(&phy->dev, "Invalid bits per LVDS data lane: %u\n",
> > > > + lvds_cfg->bits_per_lane_and_dclk_cycle);
> > > > + return -EINVAL;
> > > > + }
> > > > +
> > > > + if (lvds_cfg->lanes != 4) {
> > > > + dev_err(&phy->dev, "Invalid LVDS data lanes: %u\n",
> > > > + lvds_cfg->lanes);
> > > > + return -EINVAL;
> > > > + }
> > > > +
> > > > + if (lvds_cfg->differential_clk_rate < MIN_LVDS_REFCLK_FREQ ||
> > > > + lvds_cfg->differential_clk_rate > MAX_LVDS_REFCLK_FREQ) {
> > > > + dev_err(&phy->dev,
> > > > + "Invalid LVDS differential clock rate: %lu\n",
> > > > + lvds_cfg->differential_clk_rate);
> > > > + return -EINVAL;
> > > > + }
> > > > +
> > > > + return 0;
> > > > +}
> > > > +
> > > > static int mixel_dphy_validate(struct phy *phy, enum phy_mode mode, int submode,
> > > > union phy_configure_opts *opts)
> > > > {
> > > > - struct mixel_dphy_cfg cfg = { 0 };
> > > > + if (mode == PHY_MODE_MIPI_DPHY) {
> > > > + struct mixel_dphy_cfg mipi_dphy_cfg = { 0 };
> > > >
> > > > - if (mode != PHY_MODE_MIPI_DPHY)
> > > > - return -EINVAL;
> > > > + return mixel_dphy_config_from_opts(phy, &opts->mipi_dphy,
> > > > + &mipi_dphy_cfg);
> > > > + } else if (mode == PHY_MODE_LVDS) {
> > > > + return mixel_dphy_validate_lvds_phy(phy, opts);
> > > > + }
> > > >
> > > > - return mixel_dphy_config_from_opts(phy, &opts->mipi_dphy, &cfg);
> > > > + dev_err(&phy->dev, "Failed to validate PHY with invalid PHY mode\n");
> > >
> > > Can you print the `mode` here so it becomes obvious from the error what
> > > incorrect mode got passed in?
> >
> > Will do in the next version.
> >
> > > > + return -EINVAL;
> > > > }
> > > >
> > > > static int mixel_dphy_init(struct phy *phy)
> > > > @@ -373,27 +507,74 @@ static int mixel_dphy_exit(struct phy *phy)
> > > > return 0;
> > > > }
> > > >
> > > > -static int mixel_dphy_power_on(struct phy *phy)
> > > > +static int mixel_dphy_power_on_mipi_dphy(struct phy *phy)
> > > > {
> > > > struct mixel_dphy_priv *priv = phy_get_drvdata(phy);
> > > > u32 locked;
> > > > int ret;
> > > >
> > > > - ret = clk_prepare_enable(priv->phy_ref_clk);
> > > > - if (ret < 0)
> > > > - return ret;
> > > > -
> > > > phy_write(phy, PWR_ON, DPHY_PD_PLL);
> > > > ret = regmap_read_poll_timeout(priv->regmap, DPHY_LOCK, locked,
> > > > locked, PLL_LOCK_SLEEP,
> > > > PLL_LOCK_TIMEOUT);
> > > > if (ret < 0) {
> > > > dev_err(&phy->dev, "Could not get DPHY lock (%d)!\n", ret);
> > > > - goto clock_disable;
> > > > + return ret;
> > > > }
> > > > phy_write(phy, PWR_ON, DPHY_PD_DPHY);
> > > >
> > > > return 0;
> > > > +}
> > > > +
> > > > +static int mixel_dphy_power_on_lvds_phy(struct phy *phy)
> > > > +{
> > > > + struct mixel_dphy_priv *priv = phy_get_drvdata(phy);
> > > > + u32 locked;
> > > > + int ret;
> > > > +
> > > > + regmap_update_bits(priv->lvds_regmap, PHY_CTRL, LVDS_EN, LVDS_EN);
> > > > +
> > > > + phy_write(phy, PWR_ON, DPHY_PD_DPHY);
> > > > + phy_write(phy, PWR_ON, DPHY_PD_PLL);
> > > > +
> > > > + /* do not wait for slave LVDS PHY being locked */
> > > > + if (priv->is_slave)
> > > > + return 0;
> > > > +
> > > > + ret = regmap_read_poll_timeout(priv->regmap, DPHY_LOCK, locked,
> > > > + locked, PLL_LOCK_SLEEP,
> > > > + PLL_LOCK_TIMEOUT);
> > > > + if (ret < 0) {
> > > > + dev_err(&phy->dev, "Could not get LVDS PHY lock (%d)!\n", ret);
> > > > + return ret;
> > > > + }
> > > > +
> > > > + return 0;
> > > > +}
> > > > +
> > > > +static int mixel_dphy_power_on(struct phy *phy)
> > > > +{
> > > > + struct mixel_dphy_priv *priv = phy_get_drvdata(phy);
> > > > + int ret;
> > > > +
> > > > + ret = clk_prepare_enable(priv->phy_ref_clk);
> > > > + if (ret < 0)
> > > > + return ret;
> > > > +
> > > > + if (phy->attrs.mode == PHY_MODE_MIPI_DPHY) {
> > > > + ret = mixel_dphy_power_on_mipi_dphy(phy);
> > > > + } else if (phy->attrs.mode == PHY_MODE_LVDS) {
> > > > + ret = mixel_dphy_power_on_lvds_phy(phy);
> > > > + } else {
> > > > + dev_err(&phy->dev,
> > > > + "Failed to power on PHY with invalid PHY mode\n");
> > >
> > > Can you print the `mode` here so it becomes obvious from the error what
> > > incorrect mode got passed in?
> >
> > Will do in the next version.
> >
> > > > + ret = -EINVAL;
> > > > + }
> > > > +
> > > > + if (ret)
> > > > + goto clock_disable;
> > > > +
> > > > + return 0;
> > > > clock_disable:
> > > > clk_disable_unprepare(priv->phy_ref_clk);
> > > > return ret;
> > > > @@ -406,16 +587,52 @@ static int mixel_dphy_power_off(struct phy *phy)
> > > > phy_write(phy, PWR_OFF, DPHY_PD_PLL);
> > > > phy_write(phy, PWR_OFF, DPHY_PD_DPHY);
> > > >
> > > > + if (phy->attrs.mode == PHY_MODE_LVDS)
> > > > + regmap_update_bits(priv->lvds_regmap, PHY_CTRL, LVDS_EN, 0);
> > > > +
> > > > clk_disable_unprepare(priv->phy_ref_clk);
> > > >
> > > > return 0;
> > > > }
> > > >
> > > > +static int mixel_dphy_set_mode(struct phy *phy, enum phy_mode mode, int submode)
> > > > +{
> > > > + struct mixel_dphy_priv *priv = phy_get_drvdata(phy);
> > > > + int ret;
> > > > +
> > >
> > > I'd reject all modes except PHY_MODE_MIPI_DPHY and PHY_MODE_MIPI_LVDS upfront...
> >
> > It seems that this overall rejection would cause _double_ check
> > together with the snippet right below, which should be avoided.
> >
> > > > + /* Currently, MIPI DPHY mode only, if it's not a combo PHY. */
> > > > + if (!priv->devdata->is_combo && mode != PHY_MODE_MIPI_DPHY) {
> > > > + dev_err(&phy->dev, "Failed to set PHY mode to MIPI DPHY\n");
> > > > + return -EINVAL;
> > > > + }
> > > > +
> > > > + if (priv->devdata->is_combo && mode != PHY_MODE_LVDS) {
> > > > + dev_err(&phy->dev, "Failed to set PHY mode for combo PHY\n");
> > > > + return -EINVAL;
> > > > + }
> > >
> > > ...and then just reject on whetehr `is_combo` is set or not. This makes
> > > it easier to add more later.
> >
> > The above snippet is rejecting on whether 'is_combo' is set or not.
> > So, in short, the current implementation looks ok to me.
> > Or, things still can be improved here?
>
> I agree, i think what tripped me up is that the double negative check
> comes first comined with the comment so i'd just drop the comment and
> start with the positive one:
>
> if (priv->devdata->is_combo && mode != PHY_MODE_LVDS) {
> dev_err(&phy->dev, "Failed to set PHY mode for combo PHY\n");
> return -EINVAL;
> }
>
> if (!priv->devdata->is_combo && mode != PHY_MODE_MIPI_DPHY) {
> dev_err(&phy->dev, "Failed to set PHY mode to MIPI DPHY\n");
> return -EINVAL;
> }

Ok. I'll use this snippet.

Thanks,
Liu Ying

>
> Cheers,
> -- Guido
>
> > Thanks,
> > Liu Ying
> >
> > > > + if (priv->devdata->is_combo) {
> > > > + u32 rsc = priv->id ? IMX_SC_R_MIPI_1 : IMX_SC_R_MIPI_0;
> > > > +
> > > > + ret = imx_sc_misc_set_control(priv->ipc_handle,
> > > > + rsc, IMX_SC_C_MODE,
> > > > + mode == PHY_MODE_LVDS);
> > > > + if (ret) {
> > > > + dev_err(&phy->dev,
> > > > + "Failed to set PHY mode via SCU ipc: %d\n", ret);
> > > > + return ret;
> > > > + }
> > > > + }
> > > > +
> > > > + return 0;
> > > > +}
> > > > +
> > > > static const struct phy_ops mixel_dphy_phy_ops = {
> > > > .init = mixel_dphy_init,
> > > > .exit = mixel_dphy_exit,
> > > > .power_on = mixel_dphy_power_on,
> > > > .power_off = mixel_dphy_power_off,
> > > > + .set_mode = mixel_dphy_set_mode,
> > > > .configure = mixel_dphy_configure,
> > > > .validate = mixel_dphy_validate,
> > > > .owner = THIS_MODULE,
> > > > @@ -424,6 +641,8 @@ static const struct phy_ops mixel_dphy_phy_ops = {
> > > > static const struct of_device_id mixel_dphy_of_match[] = {
> > > > { .compatible = "fsl,imx8mq-mipi-dphy",
> > > > .data = &mixel_dphy_devdata[MIXEL_IMX8MQ] },
> > > > + { .compatible = "fsl,imx8qxp-mipi-dphy",
> > > > + .data = &mixel_dphy_devdata[MIXEL_IMX8QXP] },
> > > > { /* sentinel */ },
> > > > };
> > > > MODULE_DEVICE_TABLE(of, mixel_dphy_of_match);
> > > > @@ -436,6 +655,7 @@ static int mixel_dphy_probe(struct platform_device *pdev)
> > > > struct mixel_dphy_priv *priv;
> > > > struct phy *phy;
> > > > void __iomem *base;
> > > > + int ret;
> > > >
> > > > if (!np)
> > > > return -ENODEV;
> > > > @@ -467,6 +687,30 @@ static int mixel_dphy_probe(struct platform_device *pdev)
> > > > dev_dbg(dev, "phy_ref clock rate: %lu\n",
> > > > clk_get_rate(priv->phy_ref_clk));
> > > >
> > > > + if (priv->devdata->is_combo) {
> > > > + priv->lvds_regmap =
> > > > + syscon_regmap_lookup_by_phandle(np, "fsl,syscon");
> > > > + if (IS_ERR(priv->lvds_regmap)) {
> > > > + ret = PTR_ERR(priv->lvds_regmap);
> > > > + dev_err_probe(dev, ret, "Failed to get LVDS regmap\n");
> > > > + return ret;
> > > > + }
> > > > +
> > > > + priv->id = of_alias_get_id(np, "mipi_dphy");
> > > > + if (priv->id < 0) {
> > > > + dev_err(dev, "Failed to get phy node alias id: %d\n",
> > > > + priv->id);
> > > > + return priv->id;
> > > > + }
> > > > +
> > > > + ret = imx_scu_get_handle(&priv->ipc_handle);
> > > > + if (ret) {
> > > > + dev_err_probe(dev, ret,
> > > > + "Failed to get SCU ipc handle\n");
> > > > + return ret;
> > > > + }
> > > > + }
> > > > +
> > > > dev_set_drvdata(dev, priv);
> > > >
> > > > phy = devm_phy_create(dev, np, &mixel_dphy_phy_ops);
> > > > --
> > > > 2.7.4
> > > >
> > >
> > > Cheers,
> > > -- Guido

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