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From:   Adrian Ratiu <adrian.ratiu@collabora.com>
To:     Enric Balletbo i Serra <enric.balletbo@collabora.com>,
        linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org,
        linux-rockchip@lists.infradead.org,
        Laurent Pinchart <Laurent.pinchart@ideasonboard.com>
Cc:     Andrzej Hajda <a.hajda@samsung.com>,
        Jonas Karlman <jonas@kwiboo.se>,
        Jernej Skrabec <jernej.skrabec@siol.net>,
        Heiko Stuebner <heiko@sntech.de>, linux-kernel@vger.kernel.org,
        dri-devel@lists.freedesktop.org, linux-imx@nxp.com,
        kernel@collabora.com, linux-stm32@st-md-mailman.stormreply.com,
        Fabio Estevam <festevam@gmail.com>,
        Enric Balletbo Serra <eballetbo@gmail.com>,
        Emil Velikov <emil.velikov@collabora.com>,
        Adrian Pop <pop.adrian61@gmail.com>,
        Arnaud Ferraris <arnaud.ferraris@collabora.com>,
        Sjoerd Simons <sjoerd.simons@collabora.com>,
        Martyn Welch <martyn.welch@collabora.com>
Subject: Re: [PATCH v8 05/10] drm: imx: Add i.MX 6 MIPI DSI host platform
 driver
In-Reply-To: <26ac2e23-f678-0c12-9a0d-d09fcb236e44@collabora.com>
References: <20200427081952.3536741-1-adrian.ratiu@collabora.com>
 <20200427081952.3536741-6-adrian.ratiu@collabora.com>
 <26ac2e23-f678-0c12-9a0d-d09fcb236e44@collabora.com>
Date:   Mon, 27 Apr 2020 21:26:26 +0300
Message-ID: <87sggoiy3x.fsf@collabora.com>
MIME-Version: 1.0
Content-Type: text/plain; format=flowed
Sender: linux-kernel-owner@vger.kernel.org
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Hi Enric,

Thank you very much for your review, comments below.

I'll leave this a bit more on review before resending with your 
suggested fixes.

On Mon, 27 Apr 2020, Enric Balletbo i Serra 
<enric.balletbo@collabora.com> wrote:
> 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@freescale.com> 
>>  Cc: Fabio Estevam <festevam@gmail.com> Cc: Enric Balletbo 
>> Serra <eballetbo@gmail.com> Reviewed-by: Emil Velikov 
>> <emil.velikov@collabora.com> Tested-by: Adrian Pop 
>> <pop.adrian61@gmail.com> Tested-by: Arnaud Ferraris 
>> <arnaud.ferraris@collabora.com> Signed-off-by: Sjoerd Simons 
>> <sjoerd.simons@collabora.com> Signed-off-by: Martyn Welch 
>> <martyn.welch@collabora.com> Signed-off-by: Adrian Ratiu 
>> <adrian.ratiu@collabora.com> --- 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? 
>

According to the imx6 ref manual, 27Mhz is the maximum value of 
the D-PHY TX refclk used to drive the display in high-speed mode 
(in low power modes this clock is disabled). It's range is [6,27] 
Mhz.

The manual-provided tables and examples for operating the 
controller always assumes the ref clk is set to 27Mhz which allows 
a maximum of
1Ghz pll and 125 Mhz byte clocks achieving 1000 lane mbps.

This driver does the same thing as the imx manual if you look at 
the definition of `dptdin_map` above which is used to compute the 
maximum lane speed for the specific mode clock.

In theory I guess power consumption can be lowered by using a 
less-than max value for the refclk, but I've never seen this done 
in practice and is very application specific... Of course, if this 
is a real power-save gain and people care about it, optimized 
tables can be added later :)

If refclk is not set to 27Mhz, in the worst case, the 
configuration done in imx_mipi_dsi_phy_init() and 
imx_mipi_dsi_get_lane_mbps() based on the values provided in 
`dptdin_map` won't be able to drive the display.

So I guess the best course of action is to drop this warn and make 
it an error in the platform driver bind() when enabling the clock, 
right?

>> + +	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. 
>

Yes, I will do this and all the other suggestions you made 
below. Thanks!

BTW I also noticed the below prints are wrong, will also fix them.
 
>> +		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@nxp.com>");
>> +MODULE_AUTHOR("Adrian Ratiu <adrian.ratiu@collabora.com>");
>> +MODULE_LICENSE("GPL");
>>