Re: [PATCH v8 05/10] drm: imx: Add i.MX 6 MIPI DSI host platform driver

[Enric Balletbo i Serra]

Hi Adrian

Thank you for your patch.

On 27/4/20 10:19, Adrian Ratiu wrote:
> This adds support for the Synopsis DesignWare MIPI DSI v1.01 host
> controller which is embedded in i.MX 6 SoCs.
> 
> Based on following patches, but updated/extended to work with existing
> support found in the kernel:
> 
> - drm: imx: Support Synopsys DesignWare MIPI DSI host controller
>   Signed-off-by: Liu Ying <Ying.Liu@xxxxxxxxxxxxx>
> 
> Cc: Fabio Estevam <festevam@xxxxxxxxx>
> Cc: Enric Balletbo Serra <eballetbo@xxxxxxxxx>
> Reviewed-by: Emil Velikov <emil.velikov@xxxxxxxxxxxxx>
> Tested-by: Adrian Pop <pop.adrian61@xxxxxxxxx>
> Tested-by: Arnaud Ferraris <arnaud.ferraris@xxxxxxxxxxxxx>
> Signed-off-by: Sjoerd Simons <sjoerd.simons@xxxxxxxxxxxxx>
> Signed-off-by: Martyn Welch <martyn.welch@xxxxxxxxxxxxx>
> Signed-off-by: Adrian Ratiu <adrian.ratiu@xxxxxxxxxxxxx>
> ---
> Changes since v7:
>   - Removed encoder helper ops and added drm_bridge (Laurent)
>   - Brought back drm_simple_encoder_init and dropped dependency on
>   external unify encoder creation patch (Laurent)
>   - Minor typo fixes
> 
> Changes since v6:
>   - Replaced custom noop encoder with the simple drm encoder (Enric)
>   - Added CONFIG_DRM_IMX6_MIPI_DSI depends on CONFIG_OF (Enric)
>   - Dropped imx_mipi_dsi_register() because now it only creates the
>   dummy encoder which can easily be done directly in imx_dsi_bind()
> 
> Changes since v5:
>   - Reword to remove unrelated device tree patch mention (Fabio)
>   - Move pllref_clk enable/disable to bind/unbind (Ezequiel)
>   - Fix freescale.com -> nxp.com email addresses (Fabio)
>   - Also added myself as module author (Fabio)
>   - Use DRM_DEV_* macros for consistency, print more error msg
> 
> Changes since v4:
>   - Split off driver-specific configuration of phy timings due
>   to new upstream API.
>   - Move regmap infrastructure logic to separate commit (Ezequiel)
>   - Move dsi v1.01 layout addition to a separate commit (Ezequiel)
>   - Minor warnings and driver name fixes
> 
> Changes since v3:
>   - Renamed platform driver to reflect it's i.MX6 only. (Fabio)
> 
> Changes since v2:
>   - Fixed commit tags. (Emil)
> 
> Changes since v1:
>   - Moved register definitions & regmap initialization into bridge
>   module. Platform drivers get the regmap via plat_data after
>   calling the bridge probe. (Emil)
> ---
>  drivers/gpu/drm/imx/Kconfig            |   8 +
>  drivers/gpu/drm/imx/Makefile           |   1 +
>  drivers/gpu/drm/imx/dw_mipi_dsi-imx6.c | 399 +++++++++++++++++++++++++
>  3 files changed, 408 insertions(+)
>  create mode 100644 drivers/gpu/drm/imx/dw_mipi_dsi-imx6.c
> 
> diff --git a/drivers/gpu/drm/imx/Kconfig b/drivers/gpu/drm/imx/Kconfig
> index 207bf7409dfba..0dffc72df7922 100644
> --- a/drivers/gpu/drm/imx/Kconfig
> +++ b/drivers/gpu/drm/imx/Kconfig
> @@ -39,3 +39,11 @@ config DRM_IMX_HDMI
>  	depends on DRM_IMX
>  	help
>  	  Choose this if you want to use HDMI on i.MX6.
> +
> +config DRM_IMX6_MIPI_DSI
> +	tristate "Freescale i.MX6 DRM MIPI DSI"
> +	select DRM_DW_MIPI_DSI
> +	depends on DRM_IMX
> +	depends on OF
> +	help
> +	  Choose this if you want to use MIPI DSI on i.MX6.
> diff --git a/drivers/gpu/drm/imx/Makefile b/drivers/gpu/drm/imx/Makefile
> index 21cdcc2faabc8..9a7843c593478 100644
> --- a/drivers/gpu/drm/imx/Makefile
> +++ b/drivers/gpu/drm/imx/Makefile
> @@ -9,3 +9,4 @@ obj-$(CONFIG_DRM_IMX_TVE) += imx-tve.o
>  obj-$(CONFIG_DRM_IMX_LDB) += imx-ldb.o
>  
>  obj-$(CONFIG_DRM_IMX_HDMI) += dw_hdmi-imx.o
> +obj-$(CONFIG_DRM_IMX6_MIPI_DSI) += dw_mipi_dsi-imx6.o
> diff --git a/drivers/gpu/drm/imx/dw_mipi_dsi-imx6.c b/drivers/gpu/drm/imx/dw_mipi_dsi-imx6.c
> new file mode 100644
> index 0000000000000..492decc418bc3
> --- /dev/null
> +++ b/drivers/gpu/drm/imx/dw_mipi_dsi-imx6.c
> @@ -0,0 +1,399 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * i.MX6 drm driver - MIPI DSI Host Controller
> + *
> + * Copyright (C) 2011-2015 Freescale Semiconductor, Inc.
> + * Copyright (C) 2019-2020 Collabora, Ltd.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/component.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/mfd/syscon/imx6q-iomuxc-gpr.h>
> +#include <linux/module.h>
> +#include <linux/of_device.h>
> +#include <linux/regmap.h>
> +#include <linux/videodev2.h>
> +#include <drm/bridge/dw_mipi_dsi.h>
> +#include <drm/drm_atomic_state_helper.h>
> +#include <drm/drm_crtc_helper.h>
> +#include <drm/drm_mipi_dsi.h>
> +#include <drm/drm_of.h>
> +#include <drm/drm_print.h>
> +#include <drm/drm_simple_kms_helper.h>
> +
> +#include "imx-drm.h"
> +
> +#define DSI_PWR_UP			0x04
> +#define RESET				0
> +#define POWERUP				BIT(0)
> +
> +#define DSI_PHY_IF_CTRL			0x5c
> +#define PHY_IF_CTRL_RESET		0x0
> +
> +#define DSI_PHY_TST_CTRL0		0x64
> +#define PHY_TESTCLK			BIT(1)
> +#define PHY_UNTESTCLK			0
> +#define PHY_TESTCLR			BIT(0)
> +#define PHY_UNTESTCLR			0
> +
> +#define DSI_PHY_TST_CTRL1		0x68
> +#define PHY_TESTEN			BIT(16)
> +#define PHY_UNTESTEN			0
> +#define PHY_TESTDOUT(n)			(((n) & 0xff) << 8)
> +#define PHY_TESTDIN(n)			(((n) & 0xff) << 0)
> +
> +struct imx_mipi_dsi {
> +	struct drm_encoder encoder;
> +	struct drm_bridge bridge;
> +	struct device *dev;
> +	struct regmap *mux_sel;
> +	struct dw_mipi_dsi *mipi_dsi;
> +	struct clk *pllref_clk;
> +
> +	void __iomem *base;
> +	unsigned int lane_mbps;
> +};
> +
> +struct dphy_pll_testdin_map {
> +	unsigned int max_mbps;
> +	u8 testdin;
> +};
> +
> +/* The table is based on 27MHz DPHY pll reference clock. */
> +static const struct dphy_pll_testdin_map dptdin_map[] = {
> +	{160, 0x04}, {180, 0x24}, {200, 0x44}, {210, 0x06},
> +	{240, 0x26}, {250, 0x46}, {270, 0x08}, {300, 0x28},
> +	{330, 0x48}, {360, 0x2a}, {400, 0x4a}, {450, 0x0c},
> +	{500, 0x2c}, {550, 0x0e}, {600, 0x2e}, {650, 0x10},
> +	{700, 0x30}, {750, 0x12}, {800, 0x32}, {850, 0x14},
> +	{900, 0x34}, {950, 0x54}, {1000, 0x74}
> +};
> +
> +static inline struct imx_mipi_dsi *bridge_to_imxdsi(struct drm_bridge *br)
> +{
> +	return container_of(br, struct imx_mipi_dsi, bridge);
> +}
> +
> +static int
> +imx_mipi_dsi_bridge_atomic_check(struct drm_bridge *bridge,
> +				 struct drm_bridge_state *bridge_state,
> +				 struct drm_crtc_state *crtc_state,
> +				 struct drm_connector_state *conn_state)
> +{
> +	struct imx_crtc_state *imx_crtc_state = to_imx_crtc_state(crtc_state);
> +
> +	/* The following values are taken from dw_hdmi_imx_atomic_check */
> +	imx_crtc_state->bus_format = MEDIA_BUS_FMT_RGB888_1X24;
> +	imx_crtc_state->di_hsync_pin = 2;
> +	imx_crtc_state->di_vsync_pin = 3;
> +
> +	return 0;
> +}
> +
> +static void imx_mipi_dsi_bridge_atomic_enable(struct drm_bridge *bridge,
> +					      struct drm_bridge_state *old_st)
> +{
> +	struct imx_mipi_dsi *dsi = bridge_to_imxdsi(bridge);
> +	int mux = drm_of_encoder_active_port_id(dsi->dev->of_node,
> +						&dsi->encoder);
> +	/* Set IOMUX DSI output reg to correct IPU 1 or 0 and DI 1 or 0 ports */
> +	regmap_update_bits(dsi->mux_sel, IOMUXC_GPR3,
> +			   IMX6Q_GPR3_MIPI_MUX_CTL_MASK,
> +			   mux << IMX6Q_GPR3_MIPI_MUX_CTL_SHIFT);
> +}
> +
> +static const struct drm_bridge_funcs imx_dsi_bridge_funcs = {
> +	.atomic_enable = imx_mipi_dsi_bridge_atomic_enable,
> +	.atomic_check = imx_mipi_dsi_bridge_atomic_check,
> +	.atomic_reset = drm_atomic_helper_bridge_reset,
> +	.atomic_duplicate_state = drm_atomic_helper_bridge_duplicate_state,
> +	.atomic_destroy_state = drm_atomic_helper_bridge_destroy_state,
> +};
> +
> +static enum drm_mode_status imx_mipi_dsi_mode_valid(void *priv_data,
> +					const struct drm_display_mode *mode)
> +{
> +	/*
> +	 * The VID_PKT_SIZE field in the DSI_VID_PKT_CFG
> +	 * register is 11-bit.
> +	 */
> +	if (mode->hdisplay > 0x7ff)
> +		return MODE_BAD_HVALUE;
> +
> +	/*
> +	 * The V_ACTIVE_LINES field in the DSI_VTIMING_CFG
> +	 * register is 11-bit.
> +	 */
> +	if (mode->vdisplay > 0x7ff)
> +		return MODE_BAD_VVALUE;
> +
> +	return MODE_OK;
> +}
> +
> +
> +static unsigned int max_mbps_to_testdin(unsigned int max_mbps)
> +{
> +	unsigned int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(dptdin_map); i++)
> +		if (dptdin_map[i].max_mbps == max_mbps)
> +			return dptdin_map[i].testdin;
> +
> +	return -EINVAL;
> +}
> +
> +static inline void dsi_write(struct imx_mipi_dsi *dsi, u32 reg, u32 val)
> +{
> +	writel(val, dsi->base + reg);
> +}
> +
> +static int imx_mipi_dsi_phy_init(void *priv_data)
> +{
> +	struct imx_mipi_dsi *dsi = priv_data;
> +	int testdin;
> +
> +	testdin = max_mbps_to_testdin(dsi->lane_mbps);
> +	if (testdin < 0) {
> +		DRM_DEV_ERROR(dsi->dev,
> +			      "failed to get testdin for %dmbps lane clock\n",
> +			      dsi->lane_mbps);
> +		return testdin;
> +	}
> +
> +	dsi_write(dsi, DSI_PHY_IF_CTRL, PHY_IF_CTRL_RESET);
> +	dsi_write(dsi, DSI_PWR_UP, POWERUP);
> +
> +	dsi_write(dsi, DSI_PHY_TST_CTRL0, PHY_UNTESTCLK | PHY_UNTESTCLR);
> +	dsi_write(dsi, DSI_PHY_TST_CTRL1, PHY_TESTEN | PHY_TESTDOUT(0) |
> +		  PHY_TESTDIN(0x44));
> +	dsi_write(dsi, DSI_PHY_TST_CTRL0, PHY_TESTCLK | PHY_UNTESTCLR);
> +	dsi_write(dsi, DSI_PHY_TST_CTRL0, PHY_UNTESTCLK | PHY_UNTESTCLR);
> +	dsi_write(dsi, DSI_PHY_TST_CTRL1, PHY_UNTESTEN | PHY_TESTDOUT(0) |
> +		  PHY_TESTDIN(testdin));
> +	dsi_write(dsi, DSI_PHY_TST_CTRL0, PHY_TESTCLK | PHY_UNTESTCLR);
> +	dsi_write(dsi, DSI_PHY_TST_CTRL0, PHY_UNTESTCLK | PHY_UNTESTCLR);
> +
> +	return 0;
> +}
> +
> +static int imx_mipi_dsi_get_lane_mbps(void *priv_data,
> +				      const struct drm_display_mode *mode,
> +				      unsigned long mode_flags, u32 lanes,
> +				      u32 format, unsigned int *lane_mbps)
> +{
> +	struct imx_mipi_dsi *dsi = priv_data;
> +	int bpp;
> +	unsigned int i, target_mbps, mpclk;
> +	unsigned long pllref;
> +
> +	bpp = mipi_dsi_pixel_format_to_bpp(format);
> +	if (bpp < 0) {
> +		DRM_DEV_ERROR(dsi->dev, "failed to get bpp for format %d: %d\n",
> +			      format, bpp);
> +		return bpp;
> +	}
> +
> +	pllref = clk_get_rate(dsi->pllref_clk);
> +	if (pllref != 27000000)
> +		DRM_WARN("DSI pllref_clk not set to 27Mhz\n");

This pllref variable is only used to print this warning, what's the point of
warn and ignore it? If pllref is not set at 27MHz what will happen?

> +
> +	mpclk = DIV_ROUND_UP(mode->clock, MSEC_PER_SEC);
> +	if (mpclk) {
> +		/* take 1/0.7 blanking overhead into consideration */
> +		target_mbps = (mpclk * (bpp / lanes) * 10) / 7;
> +	} else {
> +		DRM_DEV_ERROR(dsi->dev, "use default 1Gbps DPHY pll clock\n");

That's really an error? Looks to me that's just a fallback if mpclk is zero.
Maybe set the level to INFO or even better DEBUG.

> +		target_mbps = 1000;
> +	}
> +
> +	DRM_DEV_DEBUG(dsi->dev, "target pllref_clk frequency is %uMbps\n",
> +		      target_mbps);
> +
> +	for (i = 0; i < ARRAY_SIZE(dptdin_map); i++) {
> +		if (target_mbps < dptdin_map[i].max_mbps) {
> +			*lane_mbps = dptdin_map[i].max_mbps;
> +			dsi->lane_mbps = *lane_mbps;
> +			DRM_DEV_DEBUG(dsi->dev,
> +				      "real pllref_clk frequency is %uMbps\n",
> +				      *lane_mbps);
> +			return 0;
> +		}
> +	}
> +
> +	DRM_DEV_ERROR(dsi->dev, "DPHY clock frequency %uMbps is out of range\n",
> +		      target_mbps);
> +
> +	return -EINVAL;
> +}
> +
> +static int
> +dw_mipi_dsi_phy_get_timing(void *priv_data, unsigned int lane_mbps,
> +			   struct dw_mipi_dsi_dphy_timing *timing)
> +{
> +	timing->clk_hs2lp = 0x40;
> +	timing->clk_lp2hs = 0x40;
> +	timing->data_hs2lp = 0x40;
> +	timing->data_lp2hs = 0x40;
> +
> +	return 0;
> +}
> +
> +static const struct dw_mipi_dsi_phy_ops dw_mipi_dsi_imx6_phy_ops = {
> +	.init = imx_mipi_dsi_phy_init,
> +	.get_lane_mbps = imx_mipi_dsi_get_lane_mbps,
> +	.get_timing = dw_mipi_dsi_phy_get_timing,
> +};
> +
> +static struct dw_mipi_dsi_plat_data imx6_mipi_dsi_drv_data = {
> +	.max_data_lanes = 2,
> +	.mode_valid = imx_mipi_dsi_mode_valid,
> +	.phy_ops = &dw_mipi_dsi_imx6_phy_ops,
> +};
> +
> +static const struct of_device_id imx_dsi_dt_ids[] = {
> +	{
> +		.compatible = "fsl,imx6-mipi-dsi",
> +		.data = &imx6_mipi_dsi_drv_data,
> +	},
> +	{ /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, imx_dsi_dt_ids);
> +
> +static int imx_mipi_dsi_bind(struct device *dev, struct device *master,
> +			     void *data)
> +{
> +	struct imx_mipi_dsi *dsi = dev_get_drvdata(dev);
> +	struct drm_device *drm = data;
> +	int ret;
> +
> +	ret = clk_prepare_enable(dsi->pllref_clk);
> +	if (ret) {
> +		DRM_DEV_ERROR(dev, "Failed to enable pllref_clk: %d\n", ret);
> +		return ret;
> +	}
> +
> +	ret = imx_drm_encoder_parse_of(drm, &dsi->encoder, dsi->dev->of_node);
> +	if (ret)
> +		return ret;
> +
> +	ret = drm_simple_encoder_init(drm, &dsi->encoder, DRM_MODE_ENCODER_NONE);
> +	if (ret) {
> +		DRM_DEV_ERROR(dev, "failed to create drm encoder\n");
> +		return ret;
> +	}
> +
> +	drm_bridge_add(&dsi->bridge);

You are adding the bridge in imx_mipi_dsi_bind() but removing in
imx_mipi_dsi_remove(). Although in this case I don't think there is any bad
effect, would be nice maintain the symetry, so I'd move the drm_bridge_add()
call to the imx_mipi_dis_probe() function just before component_add().

> +
> +	drm_bridge_attach(&dsi->encoder, &dsi->bridge, NULL, 0);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(dev, "failed to attach IMX6 bridge: %d\n", ret);
> +		return ret;

If it fails you probably want to cleanup the encoder drm_cleanup_encoder()

> +	}
> +
> +	ret = dw_mipi_dsi_bind(dsi->mipi_dsi, &dsi->encoder, &dsi->bridge);
> +	if (ret) {
> +		DRM_DEV_ERROR(dev, "Failed to bind: %d\n", ret);
> +		return ret;

The same here.

> +	}
> +
> +	return 0;
> +}
> +
> +static void imx_mipi_dsi_unbind(struct device *dev, struct device *master,
> +				void *data)
> +{
> +	struct imx_mipi_dsi *dsi = dev_get_drvdata(dev);
> +
> +	dw_mipi_dsi_unbind(dsi->mipi_dsi);
> +

drm_encoder_cleanup() ?

> +	clk_disable_unprepare(dsi->pllref_clk);
> +}
> +
> +static const struct component_ops imx_mipi_dsi_ops = {
> +	.bind	= imx_mipi_dsi_bind,
> +	.unbind	= imx_mipi_dsi_unbind,
> +};
> +
> +static int imx_mipi_dsi_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	const struct of_device_id *of_id = of_match_device(imx_dsi_dt_ids, dev);
> +	struct dw_mipi_dsi_plat_data *pdata = (struct dw_mipi_dsi_plat_data *) of_id->data;
> +	struct imx_mipi_dsi *dsi;
> +	struct resource *res;
> +	int ret;
> +
> +	dsi = devm_kzalloc(dev, sizeof(*dsi), GFP_KERNEL);
> +	if (!dsi)
> +		return -ENOMEM;
> +
> +	dsi->dev = dev;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	dsi->base = devm_ioremap_resource(dev, res);
> +	if (IS_ERR(dsi->base)) {
> +		ret = PTR_ERR(dsi->base);
> +		DRM_DEV_ERROR(dev, "Unable to get dsi registers: %d\n", ret);
> +		return ret;

This print is redundant, devm_ioremap_resource will print an error already. This
code can be simply
		return PTR_ERR(res);

> +	}
> +
> +	dsi->pllref_clk = devm_clk_get(dev, "ref");
> +	if (IS_ERR(dsi->pllref_clk)) {
> +		ret = PTR_ERR(dsi->pllref_clk);
> +		DRM_DEV_ERROR(dev, "Unable to get pllref_clk: %d\n", ret);

This print is redundant, devm_clk_get will print an error already. This code can
be simply
		return PTR_ERR(dsi->pllref_clk);

> +		return ret;
> +	}
> +
> +	dsi->mux_sel = syscon_regmap_lookup_by_phandle(dev->of_node, "fsl,gpr");
> +	if (IS_ERR(dsi->mux_sel)) {
> +		ret = PTR_ERR(dsi->mux_sel);
> +		DRM_DEV_ERROR(dev, "Failed to get GPR regmap: %d\n", ret);
> +		return ret;
> +	}
> +
> +	dev_set_drvdata(dev, dsi);
> +
> +	imx6_mipi_dsi_drv_data.base = dsi->base;
> +	imx6_mipi_dsi_drv_data.priv_data = dsi;
> +
> +	dsi->bridge.driver_private = dsi;
> +	dsi->bridge.funcs = &imx_dsi_bridge_funcs;
> +	dsi->bridge.of_node = dev->of_node;

You probably want to set the bridge.type here too:

        dsi->bridge.type = DRM_MODE_CONNECTOR_DSI;

> +
> +	dsi->mipi_dsi = dw_mipi_dsi_probe(pdev, pdata);
> +	if (IS_ERR(dsi->mipi_dsi)) {
> +		ret = PTR_ERR(dsi->mipi_dsi);
> +		DRM_DEV_ERROR(dev, "Failed to probe DW DSI host: %d\n", ret);
> +		goto err_clkdisable;
> +	}
> +
> +	return component_add(&pdev->dev, &imx_mipi_dsi_ops);
> +
> +err_clkdisable:
> +	clk_disable_unprepare(dsi->pllref_clk);
> +	return ret;
> +}
> +
> +static int imx_mipi_dsi_remove(struct platform_device *pdev)
> +{
> +	struct imx_mipi_dsi *dsi = platform_get_drvdata(pdev);
> +	drm_bridge_remove(&dsi->bridge);
> +	component_del(&pdev->dev, &imx_mipi_dsi_ops);
> +	return 0;
> +}
> +
> +static struct platform_driver imx_mipi_dsi_driver = {
> +	.probe		= imx_mipi_dsi_probe,
> +	.remove		= imx_mipi_dsi_remove,
> +	.driver		= {
> +		.of_match_table = imx_dsi_dt_ids,
> +		.name	= "dw-mipi-dsi-imx6",
> +	},
> +};
> +module_platform_driver(imx_mipi_dsi_driver);
> +
> +MODULE_DESCRIPTION("i.MX6 MIPI DSI host controller driver");
> +MODULE_AUTHOR("Liu Ying <victor.liu@xxxxxxx>");
> +MODULE_AUTHOR("Adrian Ratiu <adrian.ratiu@xxxxxxxxxxxxx>");
> +MODULE_LICENSE("GPL");
>