Re: [PATCH v6 resend 5/5] phy: freescale: phy-fsl-imx8-mipi-dphy: Add i.MX8qxp LVDS PHY mode support

[Liu Ying]

Hi Vinod,

On Wed, 2022-04-13 at 11:51 +0530, Vinod Koul wrote:
> On 02-04-22, 13:24, 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>
> > Reviewed-by: Guido Günther <agx@xxxxxxxxxxx>
> > Signed-off-by: Liu Ying <victor.liu@xxxxxxx>
> > ---
> > v5->v6:
> > * No change.
> > 
> > v4->v5:
> > * No change.
> > 
> > v3->v4:
> > * Add Guido's R-b tag.
> > 
> > v2->v3:
> > * Improve readability of mixel_dphy_set_mode(). (Guido)
> > 
> > v1->v2:
> > * Print invalid PHY mode in dmesg. (Guido)
> > 
> >  .../phy/freescale/phy-fsl-imx8-mipi-dphy.c    | 269
> > +++++++++++++++++-
> >  1 file changed, 258 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 a95572b397ca..af1ecda091c7 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)
> 
> Please dont change things like this.. A patch should do only one
> thing :)

The function name is changed by purpose - the phy in i.MX8qxp SoC is a
combo phy(lvds or mipi dphy). The new function name can be
distinguished from the added function mixel_dphy_configure_lvds_phy().

> 
> >  {
> >  	struct mixel_dphy_priv *priv = phy_get_drvdata(phy);
> >  	struct mixel_dphy_cfg cfg = { 0 };
> > @@ -345,15 +376,121 @@ 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;
> 
> I think you should check if lvds_opts is valid before dereferencing
> it..

In next verstion, I may check !opts in mixel_dphy_configure() for both
lvds and mipi dphy.

> 
> > +
> > +	/* LVDS interface pins */
> > +	regmap_write(priv->lvds_regmap, PHY_CTRL, CCM(0x5) | CA(0x4) |
> > RFB);
> 
> can we avoid magic numbers?

Will add macros CCM_1_2V and CA_3_51MA in next version.

> 
> > +
> > +	/* 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: %d\n",
> > +							phy-
> > >attrs.mode);
> 
> single line for this please

Will do.

> 
> > +	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);
> 
> here too, make it better read

Ok.

> 
> > +		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)
> > ;
> 
> the line should be justified to previos line open brace (checkpatch
> --strict will warn you about this style miss)

Ok. Will suppress all 'checkpatch --strict' warnings.

Regards,
Liu Ying