Re: [PATCH v9 2/2] phy: Add driver for mixel mipi dphy found on NXP's i.MX8 SoCs

[Fabio Estevam <festevam@gmail.com>]

Hi Guido,

On Tue, Apr 30, 2019 at 11:40 AM Guido Günther <agx@sigxcpu.org> wrote:
>
> This adds support for the Mixel DPHY as found on i.MX8 CPUs but since
> this is an IP core it will likely be found on others in the future. So
> instead of adding this to the nwl host driver make it a generic PHY
> driver.
>
> The driver supports the i.MX8MQ. Support for i.MX8QM and i.MX8QXP can be
> added once the necessary system controller bits are in via
> mixel_dphy_devdata.
>
> Co-authored-by: Robert Chiras <robert.chiras@nxp.com>
> Signed-off-by: Guido Günther <agx@sigxcpu.org>

I wish I could test it on a imx8m-evk , but there are some other
pieces needed such as Northwest Logic driver, mxsfb changes for
supporting mx8m, OLED panel driver, etc

Anyway, it looks good to me and I have only a few minor comments:

> ---
>  drivers/phy/freescale/Kconfig                 |  11 +
>  drivers/phy/freescale/Makefile                |   1 +
>  .../phy/freescale/phy-fsl-imx8-mipi-dphy.c    | 506 ++++++++++++++++++
>  3 files changed, 518 insertions(+)
>  create mode 100644 drivers/phy/freescale/phy-fsl-imx8-mipi-dphy.c
>
> diff --git a/drivers/phy/freescale/Kconfig b/drivers/phy/freescale/Kconfig
> index 832670b4952b..a111b130f9d2 100644
> --- a/drivers/phy/freescale/Kconfig
> +++ b/drivers/phy/freescale/Kconfig
> @@ -3,3 +3,14 @@ config PHY_FSL_IMX8MQ_USB
>         depends on OF && HAS_IOMEM
>         select GENERIC_PHY
>         default ARCH_MXC && ARM64
> +
> +config PHY_MIXEL_MIPI_DPHY
> +       tristate "Mixel MIPI DSI PHY support"
> +       depends on OF && HAS_IOMEM
> +       select GENERIC_PHY
> +       select GENERIC_PHY_MIPI_DPHY
> +       select REGMAP_MMIO
> +       default ARCH_MXC && ARM64

I don't think that this default is a good idea.

There are imx8m systems that do not have display, so in this case it
does not make sense to always force the build of this driver.

> +       help
> +         Enable this to add support for the Mixel DSI PHY as found
> +         on NXP's i.MX8 family of SOCs.
> diff --git a/drivers/phy/freescale/Makefile b/drivers/phy/freescale/Makefile
> index dc2b3f1f2f80..07491c926a2c 100644
> --- a/drivers/phy/freescale/Makefile
> +++ b/drivers/phy/freescale/Makefile
> @@ -1 +1,2 @@
>  obj-$(CONFIG_PHY_FSL_IMX8MQ_USB)       += phy-fsl-imx8mq-usb.o
> +obj-$(CONFIG_PHY_MIXEL_MIPI_DPHY)      += phy-fsl-imx8-mipi-dphy.o
> diff --git a/drivers/phy/freescale/phy-fsl-imx8-mipi-dphy.c b/drivers/phy/freescale/phy-fsl-imx8-mipi-dphy.c
> new file mode 100644
> index 000000000000..d6b5af0b3380
> --- /dev/null
> +++ b/drivers/phy/freescale/phy-fsl-imx8-mipi-dphy.c
> @@ -0,0 +1,506 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Copyright 2017,2018 NXP
> + * Copyright 2019 Purism SPC
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/clk-provider.h>
> +#include <linux/delay.h>
> +#include <linux/io.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_platform.h>
> +#include <linux/regmap.h>
> +#include <linux/phy/phy.h>

Please keep the headers sorted.

> +#include <linux/platform_device.h>


> +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)
> +               return -EINVAL;
> +
> +       return mixel_dphy_config_from_opts(phy, &opts->mipi_dphy, &cfg);
> +}
> +
> +

A single blank line is enough.

> +static int mixel_dphy_init(struct phy *phy)
> +{
> +       phy_write(phy, PWR_OFF, DPHY_PD_PLL);
> +       phy_write(phy, PWR_OFF, DPHY_PD_DPHY);
> +
> +       return 0;
> +}
> +
> +

Ditto.

> +static int mixel_dphy_exit(struct phy *phy)
> +{
> +       phy_write(phy, 0, DPHY_CM);
> +       phy_write(phy, 0, DPHY_CN);
> +       phy_write(phy, 0, DPHY_CO);
> +
> +       return 0;
> +}
> +
> +

Ditto.

> +static int mixel_dphy_power_off(struct phy *phy)
> +{
> +       struct mixel_dphy_priv *priv = phy_get_drvdata(phy);
> +
> +       phy_write(phy, PWR_OFF, DPHY_PD_PLL);
> +       phy_write(phy, PWR_OFF, DPHY_PD_DPHY);
> +
> +       clk_disable_unprepare(priv->phy_ref_clk);
> +
> +       return 0;
> +}
> +
> +

Ditto.

> +       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +       regs = devm_ioremap_resource(dev, res);
> +       if (IS_ERR(regs)) {
> +               dev_err(dev, "Couldn't map the DPHY registers\n");

You can skip this error message, because the core already complains on
ioremap failures.