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Date:   Fri, 28 Aug 2020 21:58:44 +0200
From:   Sam Ravnborg <sam@ravnborg.org>
To:     Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Cc:     devicetree@vger.kernel.org, dri-devel@lists.freedesktop.org,
        linux-arm-msm@vger.kernel.org, Rob Herring <robh+dt@kernel.org>,
        Daniel Vetter <daniel@ffwll.ch>,
        David Airlie <airlied@linux.ie>,
        Andrzej Hajda <a.hajda@samsung.com>,
        Neil Armstrong <narmstrong@baylibre.com>,
        Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
        Jonas Karlman <jonas@kwiboo.se>,
        Jernej Skrabec <jernej.skrabec@siol.net>,
        Vinod Koul <vkoul@kernel.org>
Subject: Re: [PATCH v2 2/3] drm: bridge: add support for lontium LT9611UXC
 bridge
Message-ID: <20200828195844.GB668578@ravnborg.org>
References: <20200828154906.1662611-1-dmitry.baryshkov@linaro.org>
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Hi Dmitry

On Fri, Aug 28, 2020 at 06:49:05PM +0300, Dmitry Baryshkov wrote:
> Add support for Lontium LT9611UXC HDMI bridge. Lontium LT9611UXC is a
> DSI to HDMI bridge which supports two DSI ports and I2S port as an input
> and HDMI port as output. Despite name being similar to LT9611, these
> devices are different enough to warrant separate driver.
> 
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

I have browsed the driver - most looks good but the way modes are
handled looks fishy.

The code either relies on edid or modes returned by a panel-timings
node. The panel-timings node seems to be used to override the edid info.
We do not need this in any other bridge driver today - and thus it is
questionaable if this driver needs it. If it is needed then please
document the rationale behind it - in the source code.
The binding does not exaplin anything about a panel-timings node.

If the panel-timins stuff is not needed, then remember to drop include
files that are no logner used.

And then there is mode_valid which uses a set of modes obtained from
a static list which also looks strange.

The last part can also be found in lontium-lt9611.c but that does
not make it correct.

Please see other bridge drivers.

The extra patch that makes connector creation optinal should be
merged with the first patch - there is no gain to split it in two.

There was also a few style issues, see comments in the following.

Looks forward to see a new revision.

	Sam



> ---
>  drivers/gpu/drm/bridge/Kconfig             |  13 +
>  drivers/gpu/drm/bridge/Makefile            |   1 +
>  drivers/gpu/drm/bridge/lontium-lt9611uxc.c | 774 +++++++++++++++++++++
>  3 files changed, 788 insertions(+)
>  create mode 100644 drivers/gpu/drm/bridge/lontium-lt9611uxc.c
> 
> diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
> index 3e11af4e9f63..8343fb054652 100644
> --- a/drivers/gpu/drm/bridge/Kconfig
> +++ b/drivers/gpu/drm/bridge/Kconfig
> @@ -61,6 +61,19 @@ config DRM_LONTIUM_LT9611
>  	  HDMI signals
>  	  Please say Y if you have such hardware.
>  
> +config DRM_LONTIUM_LT9611UXC
> +	tristate "Lontium LT9611UXC DSI/HDMI bridge"
> +	select SND_SOC_HDMI_CODEC if SND_SOC
> +	depends on OF
> +	select DRM_PANEL_BRIDGE
> +	select DRM_KMS_HELPER
> +	select REGMAP_I2C
> +	help
> +	  Driver for Lontium LT9611UXC DSI to HDMI bridge
> +	  chip driver that converts dual DSI and I2S to
> +	  HDMI signals
> +	  Please say Y if you have such hardware.
> +
>  config DRM_LVDS_CODEC
>  	tristate "Transparent LVDS encoders and decoders support"
>  	depends on OF
> diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
> index c589a6a7cbe1..306850a5899b 100644
> --- a/drivers/gpu/drm/bridge/Makefile
> +++ b/drivers/gpu/drm/bridge/Makefile
> @@ -3,6 +3,7 @@ obj-$(CONFIG_DRM_CDNS_DSI) += cdns-dsi.o
>  obj-$(CONFIG_DRM_CHRONTEL_CH7033) += chrontel-ch7033.o
>  obj-$(CONFIG_DRM_DISPLAY_CONNECTOR) += display-connector.o
>  obj-$(CONFIG_DRM_LONTIUM_LT9611) += lontium-lt9611.o
> +obj-$(CONFIG_DRM_LONTIUM_LT9611UXC) += lontium-lt9611uxc.o
>  obj-$(CONFIG_DRM_LVDS_CODEC) += lvds-codec.o
>  obj-$(CONFIG_DRM_MEGACHIPS_STDPXXXX_GE_B850V3_FW) += megachips-stdpxxxx-ge-b850v3-fw.o
>  obj-$(CONFIG_DRM_NXP_PTN3460) += nxp-ptn3460.o
> diff --git a/drivers/gpu/drm/bridge/lontium-lt9611uxc.c b/drivers/gpu/drm/bridge/lontium-lt9611uxc.c
> new file mode 100644
> index 000000000000..77c5aa5c6ad7
> --- /dev/null
> +++ b/drivers/gpu/drm/bridge/lontium-lt9611uxc.c
> @@ -0,0 +1,774 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2018, The Linux Foundation. All rights reserved.
> + * Copyright (c) 2019-2020. Linaro Limited.
> + */
> +
> +#include <linux/gpio/consumer.h>
> +#include <linux/interrupt.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/of_graph.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +#include <linux/regulator/consumer.h>
> +
> +#include <sound/hdmi-codec.h>
> +
> +#include <video/display_timing.h>
> +#include <video/of_display_timing.h>
> +#include <video/videomode.h>
> +
> +#include <drm/drm_probe_helper.h>
> +#include <drm/drm_atomic_helper.h>
> +#include <drm/drm_bridge.h>
> +#include <drm/drm_mipi_dsi.h>
> +#include <drm/drm_print.h>
Sort this block

> +
> +#define EDID_BLOCK_SIZE	128
> +#define EDID_NUM_BLOCKS	2
> +
> +struct lt9611uxc {
> +	struct device *dev;
> +	struct drm_bridge bridge;
> +
> +	struct regmap *regmap;
> +	/* Protects all accesses to registers by stopping the on-chip MCU */
> +	struct mutex ocm_lock;
> +
> +	struct device_node *dsi0_node;
> +	struct device_node *dsi1_node;
> +	struct mipi_dsi_device *dsi0;
> +	struct mipi_dsi_device *dsi1;
> +	struct platform_device *audio_pdev;
> +
> +	struct gpio_desc *reset_gpio;
> +	struct gpio_desc *enable_gpio;
> +
> +	bool sleep;
> +
> +	struct regulator_bulk_data supplies[2];
> +
> +	struct i2c_client *client;
> +
> +	bool hpd_supported;
> +	struct display_timings *timings;
> +	u8 edid_buf[EDID_BLOCK_SIZE * EDID_NUM_BLOCKS];
> +};
> +
> +#define LT9611_PAGE_CONTROL	0xff
> +
> +static const struct regmap_range_cfg lt9611uxc_ranges[] = {
> +	{
> +		.name = "register_range",
> +		.range_min =  0,
> +		.range_max = 0xd0ff,
> +		.selector_reg = LT9611_PAGE_CONTROL,
> +		.selector_mask = 0xff,
> +		.selector_shift = 0,
> +		.window_start = 0,
> +		.window_len = 0x100,
> +	},
> +};
> +
> +static const struct regmap_config lt9611uxc_regmap_config = {
> +	.reg_bits = 8,
> +	.val_bits = 8,
> +	.max_register = 0xffff,
> +	.ranges = lt9611uxc_ranges,
> +	.num_ranges = ARRAY_SIZE(lt9611uxc_ranges),
> +};
> +
> +struct lt9611uxc_mode {
> +	u16 hdisplay;
> +	u16 vdisplay;
> +	u8 vrefresh;
> +	u8 lanes;
> +	u8 intfs;
> +};
> +
> +static struct lt9611uxc_mode lt9611uxc_modes[] = {
> +	{ 3840, 2160, 60, 4, 2 }, /* 3840x2160 24bit 60Hz 4Lane 2ports */
> +	{ 3840, 2160, 30, 4, 2 }, /* 3840x2160 24bit 30Hz 4Lane 2ports */
> +	{ 1920, 1080, 60, 4, 1 }, /* 1080P 24bit 60Hz 4lane 1port */
> +	{ 1920, 1080, 30, 3, 1 }, /* 1080P 24bit 30Hz 3lane 1port */
> +	{ 1920, 1080, 24, 3, 1 },
> +	{ 1024, 768, 60, 4, 1},
> +	{ 800, 600, 60, 4, 1},
> +	{ 720, 480, 60, 4, 1 },
> +	{ 720, 576, 50, 2, 1 },
> +	{ 640, 480, 60, 2, 1 },
> +};
> +
> +static struct lt9611uxc *bridge_to_lt9611uxc(struct drm_bridge *bridge)
> +{
> +	return container_of(bridge, struct lt9611uxc, bridge);
> +}
> +
> +static void lt9611uxc_lock(struct lt9611uxc *lt9611uxc)
> +{
> +	mutex_lock(&lt9611uxc->ocm_lock);
> +	regmap_write(lt9611uxc->regmap, 0x80ee, 0x01);
> +}
> +
> +static void lt9611uxc_unlock(struct lt9611uxc *lt9611uxc)
> +{
> +	regmap_write(lt9611uxc->regmap, 0x80ee, 0x00);
> +	msleep(50);
> +	mutex_unlock(&lt9611uxc->ocm_lock);
> +}
If you have the data sheet then please use symbolic names for registers.

> +
> +static irqreturn_t lt9611uxc_irq_thread_handler(int irq, void *dev_id)
> +{
> +	struct lt9611uxc *lt9611uxc = dev_id;
> +	unsigned int irq_status = 0;
> +	unsigned int hpd_status = 0;
> +
> +	lt9611uxc_lock(lt9611uxc);
> +
> +	regmap_read(lt9611uxc->regmap, 0xb022, &irq_status);
> +	if (irq_status) {
> +		regmap_write(lt9611uxc->regmap, 0xb022, 0);
> +		regmap_read(lt9611uxc->regmap, 0xb023, &hpd_status);
hpd_status is read, but the read value is never used.
> +	}
> +
> +	lt9611uxc_unlock(lt9611uxc);
> +
> +	if (irq_status & 0x3 && lt9611uxc->bridge.dev)
> +		drm_kms_helper_hotplug_event(lt9611uxc->bridge.dev);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static void lt9611uxc_reset(struct lt9611uxc *lt9611uxc)
> +{
> +	gpiod_set_value_cansleep(lt9611uxc->reset_gpio, 1);
> +	msleep(20);
> +
> +	gpiod_set_value_cansleep(lt9611uxc->reset_gpio, 0);
> +	msleep(20);
> +
> +	gpiod_set_value_cansleep(lt9611uxc->reset_gpio, 1);
> +	msleep(180);
> +
> +	lt9611uxc->sleep = false;
> +}
> +
> +static void lt9611uxc_assert_5v(struct lt9611uxc *lt9611uxc)
> +{
> +	if (!lt9611uxc->enable_gpio)
> +		return;
> +
> +	gpiod_set_value_cansleep(lt9611uxc->enable_gpio, 1);
> +	msleep(20);
> +}
> +
> +static int lt9611uxc_regulator_init(struct lt9611uxc *lt9611uxc)
> +{
> +	int ret;
> +
> +	lt9611uxc->supplies[0].supply = "vdd";
> +	lt9611uxc->supplies[1].supply = "vcc";
> +
> +	ret = devm_regulator_bulk_get(lt9611uxc->dev, 2, lt9611uxc->supplies);
> +	if (ret < 0)
> +		return ret;
> +
> +	return regulator_set_load(lt9611uxc->supplies[0].consumer, 200000);
> +}
> +
> +static int lt9611uxc_regulator_enable(struct lt9611uxc *lt9611uxc)
> +{
> +	int ret;
> +
> +	ret = regulator_enable(lt9611uxc->supplies[0].consumer);
> +	if (ret < 0)
> +		return ret;
> +
> +	usleep_range(1000, 10000); /* 50000 according to dtsi */
> +
> +	ret = regulator_enable(lt9611uxc->supplies[1].consumer);
> +	if (ret < 0) {
> +		regulator_disable(lt9611uxc->supplies[0].consumer);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static struct lt9611uxc_mode *lt9611uxc_find_mode(const struct drm_display_mode *mode)
> +{
> +	int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(lt9611uxc_modes); i++) {
> +		if (lt9611uxc_modes[i].hdisplay == mode->hdisplay &&
> +		    lt9611uxc_modes[i].vdisplay == mode->vdisplay &&
> +		    lt9611uxc_modes[i].vrefresh == drm_mode_vrefresh(mode)) {
> +			return &lt9611uxc_modes[i];
> +		}
> +	}
> +
> +	return NULL;
> +}
> +
> +static struct mipi_dsi_device *lt9611uxc_attach_dsi(struct lt9611uxc *lt9611uxc,
> +						    struct device_node *dsi_node)
> +{
> +	const struct mipi_dsi_device_info info = { "lt9611uxc", 0, NULL };
> +	struct mipi_dsi_device *dsi;
> +	struct mipi_dsi_host *host;
> +	int ret;
> +
> +	host = of_find_mipi_dsi_host_by_node(dsi_node);
> +	if (!host) {
> +		dev_err(lt9611uxc->dev, "failed to find dsi host\n");
> +		return ERR_PTR(-EPROBE_DEFER);
> +	}
> +
> +	dsi = mipi_dsi_device_register_full(host, &info);
> +	if (IS_ERR(dsi)) {
> +		dev_err(lt9611uxc->dev, "failed to create dsi device\n");
> +		return dsi;
> +	}
> +
> +	dsi->lanes = 4;
> +	dsi->format = MIPI_DSI_FMT_RGB888;
> +	dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_SYNC_PULSE |
> +			  MIPI_DSI_MODE_VIDEO_HSE;
> +
> +	ret = mipi_dsi_attach(dsi);
> +	if (ret < 0) {
> +		dev_err(lt9611uxc->dev, "failed to attach dsi to host\n");
> +		mipi_dsi_device_unregister(dsi);
> +		return ERR_PTR(ret);
> +	}
> +
> +	return dsi;
> +}
> +
> +static void lt9611uxc_bridge_detach(struct drm_bridge *bridge)
> +{
> +	struct lt9611uxc *lt9611uxc = bridge_to_lt9611uxc(bridge);
> +
> +	if (lt9611uxc->dsi1) {
> +		mipi_dsi_detach(lt9611uxc->dsi1);
> +		mipi_dsi_device_unregister(lt9611uxc->dsi1);
> +	}
> +
> +	mipi_dsi_detach(lt9611uxc->dsi0);
> +	mipi_dsi_device_unregister(lt9611uxc->dsi0);
Hmm, is detach is called twice then thi will fail as the poiters are not
set back to NULL. But I think this is fine - so ignore.

> +}
> +
> +static int lt9611uxc_bridge_attach(struct drm_bridge *bridge,
> +				   enum drm_bridge_attach_flags flags)
> +{
> +	struct lt9611uxc *lt9611uxc = bridge_to_lt9611uxc(bridge);
> +	int ret;
> +
> +	if (!(flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR)) {
> +		dev_err(lt9611uxc->dev, "This bridge driver does not support providing connector!");
> +		return -EINVAL;
> +	}
> +
> +	/* Attach primary DSI */
> +	lt9611uxc->dsi0 = lt9611uxc_attach_dsi(lt9611uxc, lt9611uxc->dsi0_node);
> +	if (IS_ERR(lt9611uxc->dsi0))
> +		return PTR_ERR(lt9611uxc->dsi0);
> +
> +	/* Attach secondary DSI, if specified */
> +	if (lt9611uxc->dsi1_node) {
> +		lt9611uxc->dsi1 = lt9611uxc_attach_dsi(lt9611uxc, lt9611uxc->dsi1_node);
> +		if (IS_ERR(lt9611uxc->dsi1)) {
> +			ret = PTR_ERR(lt9611uxc->dsi1);
> +			goto err_unregister_dsi0;
> +		}
> +	}
> +
> +	return 0;
> +
> +err_unregister_dsi0:
> +	mipi_dsi_detach(lt9611uxc->dsi0);
> +	mipi_dsi_device_unregister(lt9611uxc->dsi0);
> +
> +	return ret;
> +}
> +
> +static enum drm_mode_status
> +lt9611uxc_bridge_mode_valid(struct drm_bridge *bridge,
> +			    const struct drm_display_info *info,
> +			    const struct drm_display_mode *mode)
> +{
> +	struct lt9611uxc_mode *lt9611uxc_mode;
> +
> +	lt9611uxc_mode = lt9611uxc_find_mode(mode);
> +
> +	return lt9611uxc_mode ? MODE_OK : MODE_BAD;
> +}
> +
> +static void lt9611uxc_bridge_post_disable(struct drm_bridge *bridge)
> +{
> +	struct lt9611uxc *lt9611uxc = bridge_to_lt9611uxc(bridge);
> +
> +	lt9611uxc_lock(lt9611uxc);
> +	regmap_update_bits(lt9611uxc->regmap, 0xb024, 0x1, 0x1);
> +	lt9611uxc->sleep = true;
> +	lt9611uxc_unlock(lt9611uxc);
> +}
> +
> +static void lt9611uxc_video_setup(struct lt9611uxc *lt9611uxc,
> +				  const struct drm_display_mode *mode)
> +{
> +	u32 h_total, hactive, hsync_len, hfront_porch;
> +	u32 v_total, vactive, vsync_len, vfront_porch;
> +
> +	h_total = mode->htotal;
> +	v_total = mode->vtotal;
> +
> +	hactive = mode->hdisplay;
> +	hsync_len = mode->hsync_end - mode->hsync_start;
> +	hfront_porch = mode->hsync_start - mode->hdisplay;
> +
> +	vactive = mode->vdisplay;
> +	vsync_len = mode->vsync_end - mode->vsync_start;
> +	vfront_porch = mode->vsync_start - mode->vdisplay;
> +
> +	regmap_write(lt9611uxc->regmap, 0xd00d, (u8)(v_total / 256));
> +	regmap_write(lt9611uxc->regmap, 0xd00e, (u8)(v_total % 256));
> +
> +	regmap_write(lt9611uxc->regmap, 0xd00f, (u8)(vactive / 256));
> +	regmap_write(lt9611uxc->regmap, 0xd010, (u8)(vactive % 256));
> +
> +	regmap_write(lt9611uxc->regmap, 0xd011, (u8)(h_total / 256));
> +	regmap_write(lt9611uxc->regmap, 0xd012, (u8)(h_total % 256));
> +
> +	regmap_write(lt9611uxc->regmap, 0xd013, (u8)(hactive / 256));
> +	regmap_write(lt9611uxc->regmap, 0xd014, (u8)(hactive % 256));
> +
> +	regmap_write(lt9611uxc->regmap, 0xd015, (u8)(vsync_len % 256));
> +
> +	regmap_update_bits(lt9611uxc->regmap, 0xd016, 0xf, (u8)(hsync_len / 256));
> +	regmap_write(lt9611uxc->regmap, 0xd017, (u8)(hsync_len % 256));
> +
> +	regmap_update_bits(lt9611uxc->regmap, 0xd018, 0xf, (u8)(vfront_porch / 256));
> +	regmap_write(lt9611uxc->regmap, 0xd019, (u8)(vfront_porch % 256));
> +
> +	regmap_update_bits(lt9611uxc->regmap, 0xd01a, 0xf, (u8)(hfront_porch / 256));
> +	regmap_write(lt9611uxc->regmap, 0xd01b, (u8)(hfront_porch % 256));
> +}
> +
> +static void lt9611uxc_bridge_mode_set(struct drm_bridge *bridge,
> +				      const struct drm_display_mode *mode,
> +				      const struct drm_display_mode *adj_mode)
> +{
> +	struct lt9611uxc *lt9611uxc = bridge_to_lt9611uxc(bridge);
> +
> +	if (lt9611uxc->sleep)
> +		lt9611uxc_reset(lt9611uxc);
> +
> +	lt9611uxc_lock(lt9611uxc);
> +	lt9611uxc_video_setup(lt9611uxc, mode);
> +	lt9611uxc_unlock(lt9611uxc);
> +}
> +
> +static enum drm_connector_status lt9611uxc_bridge_detect(struct drm_bridge *bridge)
> +{
> +	struct lt9611uxc *lt9611uxc = bridge_to_lt9611uxc(bridge);
> +	unsigned int reg_val = 0;
> +	int ret;
> +	int connected = 1;
> +
> +	if (lt9611uxc->hpd_supported) {
> +		lt9611uxc_lock(lt9611uxc);
> +		ret = regmap_read(lt9611uxc->regmap, 0xb023, &reg_val);
Would it be better to save this value in the irq function?
We read the same register here.

> +		lt9611uxc_unlock(lt9611uxc);
> +
> +		if (ret)
> +			dev_err(lt9611uxc->dev, "failed to read hpd status: %d\n", ret);
So if failed to read status it is considered connected. Hmm..

> +		else
> +			connected  = reg_val & BIT(1);
> +	}
> +
> +	return connected ?  connector_status_connected :
> +				connector_status_disconnected;
> +}
> +
> +static int lt9611uxc_bridge_get_modes(struct drm_bridge *bridge,
> +				      struct drm_connector *connector)
> +{
> +	struct lt9611uxc *lt9611uxc = bridge_to_lt9611uxc(bridge);
> +	struct display_timings *timings = lt9611uxc->timings;
> +	int i;
> +
> +	for (i = 0; i < timings->num_timings; i++) {
> +		struct drm_display_mode *mode = drm_mode_create(bridge->dev);
> +		struct videomode vm;
> +
> +		if (videomode_from_timings(timings, &vm, i))
> +			break;
> +
> +		drm_display_mode_from_videomode(&vm, mode);
> +
> +		mode->type = DRM_MODE_TYPE_DRIVER;
> +
> +		if (timings->native_mode == i)
> +			mode->type |= DRM_MODE_TYPE_PREFERRED;
> +
> +		drm_mode_set_name(mode);
> +		drm_mode_probed_add(connector, mode);
> +	}
> +
> +	return i;
> +}
> +
> +static int lt9611uxc_read_edid(struct lt9611uxc *lt9611uxc)
> +{
> +	int ret = 0;
> +	int i;
> +
> +	/* memset to clear old buffer, if any */
> +	memset(lt9611uxc->edid_buf, 0, sizeof(lt9611uxc->edid_buf));
> +
> +	lt9611uxc_lock(lt9611uxc);
> +
> +	regmap_write(lt9611uxc->regmap, 0xb00b, 0x10);
> +
> +#define EDID_SEG 16
> +	for (i = 0; i < 2 * EDID_BLOCK_SIZE; i += EDID_SEG) {
> +		regmap_write(lt9611uxc->regmap, 0xb00a, i);
> +		ret = regmap_noinc_read(lt9611uxc->regmap, 0xb0b0,
> +					&lt9611uxc->edid_buf[i], EDID_SEG);
> +		if (ret < 0)
> +			break;
> +	}
> +
> +	lt9611uxc_unlock(lt9611uxc);
> +	return ret;
> +}
> +
> +static int lt9611uxc_get_edid_block(void *data, u8 *buf, unsigned int block, size_t len)
> +{
> +	struct lt9611uxc *lt9611uxc = data;
> +	int ret;
> +
> +	if (len > EDID_BLOCK_SIZE)
> +		return -EINVAL;
> +
> +	if (block >= EDID_NUM_BLOCKS)
> +		return -EINVAL;
> +
> +	if (block == 0) {
> +		ret = lt9611uxc_read_edid(lt9611uxc);
> +		if (ret) {
> +			dev_err(lt9611uxc->dev, "edid read failed\n");
> +			return ret;
> +		}
> +	}
> +
> +	memcpy(buf, lt9611uxc->edid_buf + block * EDID_BLOCK_SIZE, len);
> +	return 0;
> +};
> +
> +static struct edid *lt9611uxc_bridge_get_edid(struct drm_bridge *bridge,
> +					      struct drm_connector *connector)
> +{
> +	struct lt9611uxc *lt9611uxc = bridge_to_lt9611uxc(bridge);
> +
> +	return drm_do_get_edid(connector, lt9611uxc_get_edid_block, lt9611uxc);
> +}
> +
> +static const struct drm_bridge_funcs lt9611uxc_bridge_funcs = {
> +	.attach = lt9611uxc_bridge_attach,
> +	.detach = lt9611uxc_bridge_detach,
> +	.mode_valid = lt9611uxc_bridge_mode_valid,
> +	.post_disable = lt9611uxc_bridge_post_disable,
> +	.mode_set = lt9611uxc_bridge_mode_set,
> +	.detect = lt9611uxc_bridge_detect,
> +	.get_modes = lt9611uxc_bridge_get_modes,
> +	.get_edid = lt9611uxc_bridge_get_edid,
> +};
> +
> +static int lt9611uxc_parse_dt(struct device *dev,
> +			      struct lt9611uxc *lt9611uxc)
> +{
> +	lt9611uxc->timings = of_get_display_timings(dev->of_node);
> +	if (!lt9611uxc->timings)
> +		dev_info(dev, "no display timings provided\n");
> +
> +	lt9611uxc->dsi0_node = of_graph_get_remote_node(dev->of_node, 0, -1);
> +	if (!lt9611uxc->dsi0_node) {
> +		dev_err(lt9611uxc->dev, "failed to get remote node for primary dsi\n");
> +		return -ENODEV;
> +	}
> +
> +	lt9611uxc->dsi1_node = of_graph_get_remote_node(dev->of_node, 1, -1);
> +
> +	return 0;
> +}
> +
> +static int lt9611uxc_gpio_init(struct lt9611uxc *lt9611uxc)
> +{
> +	struct device *dev = lt9611uxc->dev;
> +
> +	lt9611uxc->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
> +	if (IS_ERR(lt9611uxc->reset_gpio)) {
> +		dev_err(dev, "failed to acquire reset gpio\n");
> +		return PTR_ERR(lt9611uxc->reset_gpio);
> +	}
> +
> +	lt9611uxc->enable_gpio = devm_gpiod_get_optional(dev, "enable", GPIOD_OUT_LOW);
> +	if (IS_ERR(lt9611uxc->enable_gpio)) {
> +		dev_err(dev, "failed to acquire enable gpio\n");
> +		return PTR_ERR(lt9611uxc->enable_gpio);
> +	}
> +
> +	return 0;
> +}
> +
> +static int lt9611uxc_read_device_rev(struct lt9611uxc *lt9611uxc)
> +{
> +	unsigned int rev0, rev1, rev2;
> +	int ret;
> +
> +	lt9611uxc_lock(lt9611uxc);
> +
> +	ret = regmap_read(lt9611uxc->regmap, 0x8100, &rev0);
> +	ret |= regmap_read(lt9611uxc->regmap, 0x8101, &rev1);
> +	ret |= regmap_read(lt9611uxc->regmap, 0x8102, &rev2);
> +	if (ret)
> +		dev_err(lt9611uxc->dev, "failed to read revision: %d\n", ret);
> +	else
> +		dev_info(lt9611uxc->dev, "LT9611 revision: 0x%02x.%02x.%02x\n", rev0, rev1, rev2);
> +
> +	lt9611uxc_unlock(lt9611uxc);
> +
> +	return ret;
> +}
> +
> +static int lt9611uxc_read_version(struct lt9611uxc *lt9611uxc)
> +{
> +	unsigned int rev;
> +	int ret;
> +
> +	lt9611uxc_lock(lt9611uxc);
> +
> +	ret = regmap_read(lt9611uxc->regmap, 0xb021, &rev);
> +	if (ret)
> +		dev_err(lt9611uxc->dev, "failed to read revision: %d\n", ret);
> +	else
> +		dev_info(lt9611uxc->dev, "LT9611 version: 0x%02x\n", rev);
> +
> +	lt9611uxc_unlock(lt9611uxc);
> +
> +	return ret < 0 ? ret : rev;
> +}
> +
> +static int lt9611uxc_hdmi_hw_params(struct device *dev, void *data,
> +				    struct hdmi_codec_daifmt *fmt,
> +				    struct hdmi_codec_params *hparms)
> +{
> +	/*
> +	 * LT9611UXC will automatically detect rate and sample size, so no need
> +	 * to setup anything here.
> +	 */
> +	return 0;
> +}
> +
> +static void lt9611uxc_audio_shutdown(struct device *dev, void *data)
> +{
> +}
> +
> +static int lt9611uxc_hdmi_i2s_get_dai_id(struct snd_soc_component *component,
> +					 struct device_node *endpoint)
> +{
> +	struct of_endpoint of_ep;
> +	int ret;
> +
> +	ret = of_graph_parse_endpoint(endpoint, &of_ep);
> +	if (ret < 0)
> +		return ret;
> +
> +	/*
> +	 * HDMI sound should be located as reg = <2>
> +	 * Then, it is sound port 0
> +	 */
> +	if (of_ep.port == 2)
> +		return 0;
> +
> +	return -EINVAL;
> +}
> +
> +static const struct hdmi_codec_ops lt9611uxc_codec_ops = {
> +	.hw_params	= lt9611uxc_hdmi_hw_params,
> +	.audio_shutdown = lt9611uxc_audio_shutdown,
> +	.get_dai_id	= lt9611uxc_hdmi_i2s_get_dai_id,
> +};
Is an audio_startup() operation missing here?

> +
> +static int lt9611uxc_audio_init(struct device *dev, struct lt9611uxc *lt9611uxc)
> +{
> +	struct hdmi_codec_pdata codec_data = {
> +		.ops = &lt9611uxc_codec_ops,
> +		.max_i2s_channels = 2,
> +		.i2s = 1,
> +		.data = lt9611uxc,
> +	};
> +
> +	lt9611uxc->audio_pdev =
> +		platform_device_register_data(dev, HDMI_CODEC_DRV_NAME,
> +					      PLATFORM_DEVID_AUTO,
> +					      &codec_data, sizeof(codec_data));
> +
> +	return PTR_ERR_OR_ZERO(lt9611uxc->audio_pdev);
> +}
> +
> +static void lt9611uxc_audio_exit(struct lt9611uxc *lt9611uxc)
> +{
> +	if (lt9611uxc->audio_pdev) {
> +		platform_device_unregister(lt9611uxc->audio_pdev);
> +		lt9611uxc->audio_pdev = NULL;
> +	}
> +}
> +
> +static int lt9611uxc_probe(struct i2c_client *client,
> +			   const struct i2c_device_id *id)
> +{
> +	struct lt9611uxc *lt9611uxc;
> +	struct device *dev = &client->dev;
> +	int ret;
> +
> +	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
> +		dev_err(dev, "device doesn't support I2C\n");
> +		return -ENODEV;
> +	}
> +
> +	lt9611uxc = devm_kzalloc(dev, sizeof(*lt9611uxc), GFP_KERNEL);
> +	if (!lt9611uxc)
> +		return -ENOMEM;
> +
> +	lt9611uxc->dev = &client->dev;
> +	lt9611uxc->client = client;
> +	mutex_init(&lt9611uxc->ocm_lock);
> +
> +	lt9611uxc->regmap = devm_regmap_init_i2c(client, &lt9611uxc_regmap_config);
> +	if (IS_ERR(lt9611uxc->regmap)) {
> +		dev_err(lt9611uxc->dev, "regmap i2c init failed\n");
> +		return PTR_ERR(lt9611uxc->regmap);
> +	}
> +
> +	ret = lt9611uxc_parse_dt(&client->dev, lt9611uxc);
> +	if (ret) {
> +		dev_err(dev, "failed to parse device tree\n");
> +		return ret;
> +	}
> +
> +	ret = lt9611uxc_gpio_init(lt9611uxc);
> +	if (ret < 0)
> +		goto err_of_put;
> +
> +	ret = lt9611uxc_regulator_init(lt9611uxc);
> +	if (ret < 0)
> +		goto err_of_put;
> +
> +	lt9611uxc_assert_5v(lt9611uxc);
> +
> +	ret = lt9611uxc_regulator_enable(lt9611uxc);
> +	if (ret)
> +		goto err_of_put;
> +
> +	lt9611uxc_reset(lt9611uxc);
> +
> +	ret = lt9611uxc_read_device_rev(lt9611uxc);
> +	if (ret) {
> +		dev_err(dev, "failed to read chip rev\n");
> +		goto err_disable_regulators;
> +	}
> +
> +	ret = lt9611uxc_read_version(lt9611uxc);
> +	if (ret < 0) {
> +		dev_err(dev, "failed to read FW version\n");
> +		goto err_disable_regulators;
> +	} else if (ret == 0) {
> +		dev_err(dev, "FW version 0, FW update not supported\n");
> +		ret = -EOPNOTSUPP;
> +		goto err_disable_regulators;
> +	} else if (ret < 0x40) {
> +		dev_info(dev, "FW version 0x%x, HPD not supported\n", ret);
> +	} else {
> +		lt9611uxc->hpd_supported = true;
> +	}
> +
> +	ret = devm_request_threaded_irq(dev, client->irq, NULL,
> +					lt9611uxc_irq_thread_handler,
> +					IRQF_ONESHOT, "lt9611uxc", lt9611uxc);
> +	if (ret) {
> +		dev_err(dev, "failed to request irq\n");
> +		goto err_disable_regulators;
> +	}
> +
> +	i2c_set_clientdata(client, lt9611uxc);
> +
> +	lt9611uxc->bridge.funcs = &lt9611uxc_bridge_funcs;
> +	lt9611uxc->bridge.of_node = client->dev.of_node;
> +	lt9611uxc->bridge.ops = DRM_BRIDGE_OP_DETECT;
> +	if (lt9611uxc->timings)
> +		lt9611uxc->bridge.ops |= DRM_BRIDGE_OP_MODES;
> +	else
> +		lt9611uxc->bridge.ops |= DRM_BRIDGE_OP_EDID;
> +	if (lt9611uxc->hpd_supported)
> +		lt9611uxc->bridge.ops |= DRM_BRIDGE_OP_HPD;
> +	lt9611uxc->bridge.type = DRM_MODE_CONNECTOR_HDMIA;
> +
> +	drm_bridge_add(&lt9611uxc->bridge);
> +
> +	return lt9611uxc_audio_init(dev, lt9611uxc);
> +
> +err_disable_regulators:
> +	regulator_bulk_disable(ARRAY_SIZE(lt9611uxc->supplies), lt9611uxc->supplies);
> +
> +err_of_put:
> +	of_node_put(lt9611uxc->dsi1_node);
> +	of_node_put(lt9611uxc->dsi0_node);
> +
> +	return ret;
> +}
> +
> +static int lt9611uxc_remove(struct i2c_client *client)
> +{
> +	struct lt9611uxc *lt9611uxc = i2c_get_clientdata(client);
> +
> +	disable_irq(client->irq);
> +	lt9611uxc_audio_exit(lt9611uxc);
> +	drm_bridge_remove(&lt9611uxc->bridge);
> +
> +	mutex_destroy(&lt9611uxc->ocm_lock);
> +
> +	regulator_bulk_disable(ARRAY_SIZE(lt9611uxc->supplies), lt9611uxc->supplies);
> +
> +	of_node_put(lt9611uxc->dsi1_node);
> +	of_node_put(lt9611uxc->dsi0_node);
> +
> +	return 0;
> +}
> +
> +static struct i2c_device_id lt9611uxc_id[] = {
> +	{ "lontium,lt9611uxc", 0 },
> +	{}
> +};
> +
> +static const struct of_device_id lt9611uxc_match_table[] = {
> +	{ .compatible = "lontium,lt9611uxc" },
> +	{ }
	{ /* sentinel */ },
> +};
> +MODULE_DEVICE_TABLE(of, lt9611uxc_match_table);
> +
> +static struct i2c_driver lt9611uxc_driver = {
> +	.driver = {
> +		.name = "lt9611uxc",
> +		.of_match_table = lt9611uxc_match_table,
> +	},
> +	.probe = lt9611uxc_probe,
> +	.remove = lt9611uxc_remove,
> +	.id_table = lt9611uxc_id,
> +};
> +module_i2c_driver(lt9611uxc_driver);
> +
> +MODULE_LICENSE("GPL v2");
> -- 
> 2.28.0

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Date: Fri, 28 Aug 2020 21:58:44 +0200
From: Sam Ravnborg <sam@ravnborg.org>
To: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Subject: Re: [PATCH v2 2/3] drm: bridge: add support for lontium LT9611UXC
 bridge
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Hi Dmitry

On Fri, Aug 28, 2020 at 06:49:05PM +0300, Dmitry Baryshkov wrote:
> Add support for Lontium LT9611UXC HDMI bridge. Lontium LT9611UXC is a
> DSI to HDMI bridge which supports two DSI ports and I2S port as an input
> and HDMI port as output. Despite name being similar to LT9611, these
> devices are different enough to warrant separate driver.
> 
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

I have browsed the driver - most looks good but the way modes are
handled looks fishy.

The code either relies on edid or modes returned by a panel-timings
node. The panel-timings node seems to be used to override the edid info.
We do not need this in any other bridge driver today - and thus it is
questionaable if this driver needs it. If it is needed then please
document the rationale behind it - in the source code.
The binding does not exaplin anything about a panel-timings node.

If the panel-timins stuff is not needed, then remember to drop include
files that are no logner used.

And then there is mode_valid which uses a set of modes obtained from
a static list which also looks strange.

The last part can also be found in lontium-lt9611.c but that does
not make it correct.

Please see other bridge drivers.

The extra patch that makes connector creation optinal should be
merged with the first patch - there is no gain to split it in two.

There was also a few style issues, see comments in the following.

Looks forward to see a new revision.

	Sam



> ---
>  drivers/gpu/drm/bridge/Kconfig             |  13 +
>  drivers/gpu/drm/bridge/Makefile            |   1 +
>  drivers/gpu/drm/bridge/lontium-lt9611uxc.c | 774 +++++++++++++++++++++
>  3 files changed, 788 insertions(+)
>  create mode 100644 drivers/gpu/drm/bridge/lontium-lt9611uxc.c
> 
> diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
> index 3e11af4e9f63..8343fb054652 100644
> --- a/drivers/gpu/drm/bridge/Kconfig
> +++ b/drivers/gpu/drm/bridge/Kconfig
> @@ -61,6 +61,19 @@ config DRM_LONTIUM_LT9611
>  	  HDMI signals
>  	  Please say Y if you have such hardware.
>  
> +config DRM_LONTIUM_LT9611UXC
> +	tristate "Lontium LT9611UXC DSI/HDMI bridge"
> +	select SND_SOC_HDMI_CODEC if SND_SOC
> +	depends on OF
> +	select DRM_PANEL_BRIDGE
> +	select DRM_KMS_HELPER
> +	select REGMAP_I2C
> +	help
> +	  Driver for Lontium LT9611UXC DSI to HDMI bridge
> +	  chip driver that converts dual DSI and I2S to
> +	  HDMI signals
> +	  Please say Y if you have such hardware.
> +
>  config DRM_LVDS_CODEC
>  	tristate "Transparent LVDS encoders and decoders support"
>  	depends on OF
> diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
> index c589a6a7cbe1..306850a5899b 100644
> --- a/drivers/gpu/drm/bridge/Makefile
> +++ b/drivers/gpu/drm/bridge/Makefile
> @@ -3,6 +3,7 @@ obj-$(CONFIG_DRM_CDNS_DSI) += cdns-dsi.o
>  obj-$(CONFIG_DRM_CHRONTEL_CH7033) += chrontel-ch7033.o
>  obj-$(CONFIG_DRM_DISPLAY_CONNECTOR) += display-connector.o
>  obj-$(CONFIG_DRM_LONTIUM_LT9611) += lontium-lt9611.o
> +obj-$(CONFIG_DRM_LONTIUM_LT9611UXC) += lontium-lt9611uxc.o
>  obj-$(CONFIG_DRM_LVDS_CODEC) += lvds-codec.o
>  obj-$(CONFIG_DRM_MEGACHIPS_STDPXXXX_GE_B850V3_FW) += megachips-stdpxxxx-ge-b850v3-fw.o
>  obj-$(CONFIG_DRM_NXP_PTN3460) += nxp-ptn3460.o
> diff --git a/drivers/gpu/drm/bridge/lontium-lt9611uxc.c b/drivers/gpu/drm/bridge/lontium-lt9611uxc.c
> new file mode 100644
> index 000000000000..77c5aa5c6ad7
> --- /dev/null
> +++ b/drivers/gpu/drm/bridge/lontium-lt9611uxc.c
> @@ -0,0 +1,774 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2018, The Linux Foundation. All rights reserved.
> + * Copyright (c) 2019-2020. Linaro Limited.
> + */
> +
> +#include <linux/gpio/consumer.h>
> +#include <linux/interrupt.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/of_graph.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +#include <linux/regulator/consumer.h>
> +
> +#include <sound/hdmi-codec.h>
> +
> +#include <video/display_timing.h>
> +#include <video/of_display_timing.h>
> +#include <video/videomode.h>
> +
> +#include <drm/drm_probe_helper.h>
> +#include <drm/drm_atomic_helper.h>
> +#include <drm/drm_bridge.h>
> +#include <drm/drm_mipi_dsi.h>
> +#include <drm/drm_print.h>
Sort this block

> +
> +#define EDID_BLOCK_SIZE	128
> +#define EDID_NUM_BLOCKS	2
> +
> +struct lt9611uxc {
> +	struct device *dev;
> +	struct drm_bridge bridge;
> +
> +	struct regmap *regmap;
> +	/* Protects all accesses to registers by stopping the on-chip MCU */
> +	struct mutex ocm_lock;
> +
> +	struct device_node *dsi0_node;
> +	struct device_node *dsi1_node;
> +	struct mipi_dsi_device *dsi0;
> +	struct mipi_dsi_device *dsi1;
> +	struct platform_device *audio_pdev;
> +
> +	struct gpio_desc *reset_gpio;
> +	struct gpio_desc *enable_gpio;
> +
> +	bool sleep;
> +
> +	struct regulator_bulk_data supplies[2];
> +
> +	struct i2c_client *client;
> +
> +	bool hpd_supported;
> +	struct display_timings *timings;
> +	u8 edid_buf[EDID_BLOCK_SIZE * EDID_NUM_BLOCKS];
> +};
> +
> +#define LT9611_PAGE_CONTROL	0xff
> +
> +static const struct regmap_range_cfg lt9611uxc_ranges[] = {
> +	{
> +		.name = "register_range",
> +		.range_min =  0,
> +		.range_max = 0xd0ff,
> +		.selector_reg = LT9611_PAGE_CONTROL,
> +		.selector_mask = 0xff,
> +		.selector_shift = 0,
> +		.window_start = 0,
> +		.window_len = 0x100,
> +	},
> +};
> +
> +static const struct regmap_config lt9611uxc_regmap_config = {
> +	.reg_bits = 8,
> +	.val_bits = 8,
> +	.max_register = 0xffff,
> +	.ranges = lt9611uxc_ranges,
> +	.num_ranges = ARRAY_SIZE(lt9611uxc_ranges),
> +};
> +
> +struct lt9611uxc_mode {
> +	u16 hdisplay;
> +	u16 vdisplay;
> +	u8 vrefresh;
> +	u8 lanes;
> +	u8 intfs;
> +};
> +
> +static struct lt9611uxc_mode lt9611uxc_modes[] = {
> +	{ 3840, 2160, 60, 4, 2 }, /* 3840x2160 24bit 60Hz 4Lane 2ports */
> +	{ 3840, 2160, 30, 4, 2 }, /* 3840x2160 24bit 30Hz 4Lane 2ports */
> +	{ 1920, 1080, 60, 4, 1 }, /* 1080P 24bit 60Hz 4lane 1port */
> +	{ 1920, 1080, 30, 3, 1 }, /* 1080P 24bit 30Hz 3lane 1port */
> +	{ 1920, 1080, 24, 3, 1 },
> +	{ 1024, 768, 60, 4, 1},
> +	{ 800, 600, 60, 4, 1},
> +	{ 720, 480, 60, 4, 1 },
> +	{ 720, 576, 50, 2, 1 },
> +	{ 640, 480, 60, 2, 1 },
> +};
> +
> +static struct lt9611uxc *bridge_to_lt9611uxc(struct drm_bridge *bridge)
> +{
> +	return container_of(bridge, struct lt9611uxc, bridge);
> +}
> +
> +static void lt9611uxc_lock(struct lt9611uxc *lt9611uxc)
> +{
> +	mutex_lock(&lt9611uxc->ocm_lock);
> +	regmap_write(lt9611uxc->regmap, 0x80ee, 0x01);
> +}
> +
> +static void lt9611uxc_unlock(struct lt9611uxc *lt9611uxc)
> +{
> +	regmap_write(lt9611uxc->regmap, 0x80ee, 0x00);
> +	msleep(50);
> +	mutex_unlock(&lt9611uxc->ocm_lock);
> +}
If you have the data sheet then please use symbolic names for registers.

> +
> +static irqreturn_t lt9611uxc_irq_thread_handler(int irq, void *dev_id)
> +{
> +	struct lt9611uxc *lt9611uxc = dev_id;
> +	unsigned int irq_status = 0;
> +	unsigned int hpd_status = 0;
> +
> +	lt9611uxc_lock(lt9611uxc);
> +
> +	regmap_read(lt9611uxc->regmap, 0xb022, &irq_status);
> +	if (irq_status) {
> +		regmap_write(lt9611uxc->regmap, 0xb022, 0);
> +		regmap_read(lt9611uxc->regmap, 0xb023, &hpd_status);
hpd_status is read, but the read value is never used.
> +	}
> +
> +	lt9611uxc_unlock(lt9611uxc);
> +
> +	if (irq_status & 0x3 && lt9611uxc->bridge.dev)
> +		drm_kms_helper_hotplug_event(lt9611uxc->bridge.dev);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static void lt9611uxc_reset(struct lt9611uxc *lt9611uxc)
> +{
> +	gpiod_set_value_cansleep(lt9611uxc->reset_gpio, 1);
> +	msleep(20);
> +
> +	gpiod_set_value_cansleep(lt9611uxc->reset_gpio, 0);
> +	msleep(20);
> +
> +	gpiod_set_value_cansleep(lt9611uxc->reset_gpio, 1);
> +	msleep(180);
> +
> +	lt9611uxc->sleep = false;
> +}
> +
> +static void lt9611uxc_assert_5v(struct lt9611uxc *lt9611uxc)
> +{
> +	if (!lt9611uxc->enable_gpio)
> +		return;
> +
> +	gpiod_set_value_cansleep(lt9611uxc->enable_gpio, 1);
> +	msleep(20);
> +}
> +
> +static int lt9611uxc_regulator_init(struct lt9611uxc *lt9611uxc)
> +{
> +	int ret;
> +
> +	lt9611uxc->supplies[0].supply = "vdd";
> +	lt9611uxc->supplies[1].supply = "vcc";
> +
> +	ret = devm_regulator_bulk_get(lt9611uxc->dev, 2, lt9611uxc->supplies);
> +	if (ret < 0)
> +		return ret;
> +
> +	return regulator_set_load(lt9611uxc->supplies[0].consumer, 200000);
> +}
> +
> +static int lt9611uxc_regulator_enable(struct lt9611uxc *lt9611uxc)
> +{
> +	int ret;
> +
> +	ret = regulator_enable(lt9611uxc->supplies[0].consumer);
> +	if (ret < 0)
> +		return ret;
> +
> +	usleep_range(1000, 10000); /* 50000 according to dtsi */
> +
> +	ret = regulator_enable(lt9611uxc->supplies[1].consumer);
> +	if (ret < 0) {
> +		regulator_disable(lt9611uxc->supplies[0].consumer);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static struct lt9611uxc_mode *lt9611uxc_find_mode(const struct drm_display_mode *mode)
> +{
> +	int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(lt9611uxc_modes); i++) {
> +		if (lt9611uxc_modes[i].hdisplay == mode->hdisplay &&
> +		    lt9611uxc_modes[i].vdisplay == mode->vdisplay &&
> +		    lt9611uxc_modes[i].vrefresh == drm_mode_vrefresh(mode)) {
> +			return &lt9611uxc_modes[i];
> +		}
> +	}
> +
> +	return NULL;
> +}
> +
> +static struct mipi_dsi_device *lt9611uxc_attach_dsi(struct lt9611uxc *lt9611uxc,
> +						    struct device_node *dsi_node)
> +{
> +	const struct mipi_dsi_device_info info = { "lt9611uxc", 0, NULL };
> +	struct mipi_dsi_device *dsi;
> +	struct mipi_dsi_host *host;
> +	int ret;
> +
> +	host = of_find_mipi_dsi_host_by_node(dsi_node);
> +	if (!host) {
> +		dev_err(lt9611uxc->dev, "failed to find dsi host\n");
> +		return ERR_PTR(-EPROBE_DEFER);
> +	}
> +
> +	dsi = mipi_dsi_device_register_full(host, &info);
> +	if (IS_ERR(dsi)) {
> +		dev_err(lt9611uxc->dev, "failed to create dsi device\n");
> +		return dsi;
> +	}
> +
> +	dsi->lanes = 4;
> +	dsi->format = MIPI_DSI_FMT_RGB888;
> +	dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_SYNC_PULSE |
> +			  MIPI_DSI_MODE_VIDEO_HSE;
> +
> +	ret = mipi_dsi_attach(dsi);
> +	if (ret < 0) {
> +		dev_err(lt9611uxc->dev, "failed to attach dsi to host\n");
> +		mipi_dsi_device_unregister(dsi);
> +		return ERR_PTR(ret);
> +	}
> +
> +	return dsi;
> +}
> +
> +static void lt9611uxc_bridge_detach(struct drm_bridge *bridge)
> +{
> +	struct lt9611uxc *lt9611uxc = bridge_to_lt9611uxc(bridge);
> +
> +	if (lt9611uxc->dsi1) {
> +		mipi_dsi_detach(lt9611uxc->dsi1);
> +		mipi_dsi_device_unregister(lt9611uxc->dsi1);
> +	}
> +
> +	mipi_dsi_detach(lt9611uxc->dsi0);
> +	mipi_dsi_device_unregister(lt9611uxc->dsi0);
Hmm, is detach is called twice then thi will fail as the poiters are not
set back to NULL. But I think this is fine - so ignore.

> +}
> +
> +static int lt9611uxc_bridge_attach(struct drm_bridge *bridge,
> +				   enum drm_bridge_attach_flags flags)
> +{
> +	struct lt9611uxc *lt9611uxc = bridge_to_lt9611uxc(bridge);
> +	int ret;
> +
> +	if (!(flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR)) {
> +		dev_err(lt9611uxc->dev, "This bridge driver does not support providing connector!");
> +		return -EINVAL;
> +	}
> +
> +	/* Attach primary DSI */
> +	lt9611uxc->dsi0 = lt9611uxc_attach_dsi(lt9611uxc, lt9611uxc->dsi0_node);
> +	if (IS_ERR(lt9611uxc->dsi0))
> +		return PTR_ERR(lt9611uxc->dsi0);
> +
> +	/* Attach secondary DSI, if specified */
> +	if (lt9611uxc->dsi1_node) {
> +		lt9611uxc->dsi1 = lt9611uxc_attach_dsi(lt9611uxc, lt9611uxc->dsi1_node);
> +		if (IS_ERR(lt9611uxc->dsi1)) {
> +			ret = PTR_ERR(lt9611uxc->dsi1);
> +			goto err_unregister_dsi0;
> +		}
> +	}
> +
> +	return 0;
> +
> +err_unregister_dsi0:
> +	mipi_dsi_detach(lt9611uxc->dsi0);
> +	mipi_dsi_device_unregister(lt9611uxc->dsi0);
> +
> +	return ret;
> +}
> +
> +static enum drm_mode_status
> +lt9611uxc_bridge_mode_valid(struct drm_bridge *bridge,
> +			    const struct drm_display_info *info,
> +			    const struct drm_display_mode *mode)
> +{
> +	struct lt9611uxc_mode *lt9611uxc_mode;
> +
> +	lt9611uxc_mode = lt9611uxc_find_mode(mode);
> +
> +	return lt9611uxc_mode ? MODE_OK : MODE_BAD;
> +}
> +
> +static void lt9611uxc_bridge_post_disable(struct drm_bridge *bridge)
> +{
> +	struct lt9611uxc *lt9611uxc = bridge_to_lt9611uxc(bridge);
> +
> +	lt9611uxc_lock(lt9611uxc);
> +	regmap_update_bits(lt9611uxc->regmap, 0xb024, 0x1, 0x1);
> +	lt9611uxc->sleep = true;
> +	lt9611uxc_unlock(lt9611uxc);
> +}
> +
> +static void lt9611uxc_video_setup(struct lt9611uxc *lt9611uxc,
> +				  const struct drm_display_mode *mode)
> +{
> +	u32 h_total, hactive, hsync_len, hfront_porch;
> +	u32 v_total, vactive, vsync_len, vfront_porch;
> +
> +	h_total = mode->htotal;
> +	v_total = mode->vtotal;
> +
> +	hactive = mode->hdisplay;
> +	hsync_len = mode->hsync_end - mode->hsync_start;
> +	hfront_porch = mode->hsync_start - mode->hdisplay;
> +
> +	vactive = mode->vdisplay;
> +	vsync_len = mode->vsync_end - mode->vsync_start;
> +	vfront_porch = mode->vsync_start - mode->vdisplay;
> +
> +	regmap_write(lt9611uxc->regmap, 0xd00d, (u8)(v_total / 256));
> +	regmap_write(lt9611uxc->regmap, 0xd00e, (u8)(v_total % 256));
> +
> +	regmap_write(lt9611uxc->regmap, 0xd00f, (u8)(vactive / 256));
> +	regmap_write(lt9611uxc->regmap, 0xd010, (u8)(vactive % 256));
> +
> +	regmap_write(lt9611uxc->regmap, 0xd011, (u8)(h_total / 256));
> +	regmap_write(lt9611uxc->regmap, 0xd012, (u8)(h_total % 256));
> +
> +	regmap_write(lt9611uxc->regmap, 0xd013, (u8)(hactive / 256));
> +	regmap_write(lt9611uxc->regmap, 0xd014, (u8)(hactive % 256));
> +
> +	regmap_write(lt9611uxc->regmap, 0xd015, (u8)(vsync_len % 256));
> +
> +	regmap_update_bits(lt9611uxc->regmap, 0xd016, 0xf, (u8)(hsync_len / 256));
> +	regmap_write(lt9611uxc->regmap, 0xd017, (u8)(hsync_len % 256));
> +
> +	regmap_update_bits(lt9611uxc->regmap, 0xd018, 0xf, (u8)(vfront_porch / 256));
> +	regmap_write(lt9611uxc->regmap, 0xd019, (u8)(vfront_porch % 256));
> +
> +	regmap_update_bits(lt9611uxc->regmap, 0xd01a, 0xf, (u8)(hfront_porch / 256));
> +	regmap_write(lt9611uxc->regmap, 0xd01b, (u8)(hfront_porch % 256));
> +}
> +
> +static void lt9611uxc_bridge_mode_set(struct drm_bridge *bridge,
> +				      const struct drm_display_mode *mode,
> +				      const struct drm_display_mode *adj_mode)
> +{
> +	struct lt9611uxc *lt9611uxc = bridge_to_lt9611uxc(bridge);
> +
> +	if (lt9611uxc->sleep)
> +		lt9611uxc_reset(lt9611uxc);
> +
> +	lt9611uxc_lock(lt9611uxc);
> +	lt9611uxc_video_setup(lt9611uxc, mode);
> +	lt9611uxc_unlock(lt9611uxc);
> +}
> +
> +static enum drm_connector_status lt9611uxc_bridge_detect(struct drm_bridge *bridge)
> +{
> +	struct lt9611uxc *lt9611uxc = bridge_to_lt9611uxc(bridge);
> +	unsigned int reg_val = 0;
> +	int ret;
> +	int connected = 1;
> +
> +	if (lt9611uxc->hpd_supported) {
> +		lt9611uxc_lock(lt9611uxc);
> +		ret = regmap_read(lt9611uxc->regmap, 0xb023, &reg_val);
Would it be better to save this value in the irq function?
We read the same register here.

> +		lt9611uxc_unlock(lt9611uxc);
> +
> +		if (ret)
> +			dev_err(lt9611uxc->dev, "failed to read hpd status: %d\n", ret);
So if failed to read status it is considered connected. Hmm..

> +		else
> +			connected  = reg_val & BIT(1);
> +	}
> +
> +	return connected ?  connector_status_connected :
> +				connector_status_disconnected;
> +}
> +
> +static int lt9611uxc_bridge_get_modes(struct drm_bridge *bridge,
> +				      struct drm_connector *connector)
> +{
> +	struct lt9611uxc *lt9611uxc = bridge_to_lt9611uxc(bridge);
> +	struct display_timings *timings = lt9611uxc->timings;
> +	int i;
> +
> +	for (i = 0; i < timings->num_timings; i++) {
> +		struct drm_display_mode *mode = drm_mode_create(bridge->dev);
> +		struct videomode vm;
> +
> +		if (videomode_from_timings(timings, &vm, i))
> +			break;
> +
> +		drm_display_mode_from_videomode(&vm, mode);
> +
> +		mode->type = DRM_MODE_TYPE_DRIVER;
> +
> +		if (timings->native_mode == i)
> +			mode->type |= DRM_MODE_TYPE_PREFERRED;
> +
> +		drm_mode_set_name(mode);
> +		drm_mode_probed_add(connector, mode);
> +	}
> +
> +	return i;
> +}
> +
> +static int lt9611uxc_read_edid(struct lt9611uxc *lt9611uxc)
> +{
> +	int ret = 0;
> +	int i;
> +
> +	/* memset to clear old buffer, if any */
> +	memset(lt9611uxc->edid_buf, 0, sizeof(lt9611uxc->edid_buf));
> +
> +	lt9611uxc_lock(lt9611uxc);
> +
> +	regmap_write(lt9611uxc->regmap, 0xb00b, 0x10);
> +
> +#define EDID_SEG 16
> +	for (i = 0; i < 2 * EDID_BLOCK_SIZE; i += EDID_SEG) {
> +		regmap_write(lt9611uxc->regmap, 0xb00a, i);
> +		ret = regmap_noinc_read(lt9611uxc->regmap, 0xb0b0,
> +					&lt9611uxc->edid_buf[i], EDID_SEG);
> +		if (ret < 0)
> +			break;
> +	}
> +
> +	lt9611uxc_unlock(lt9611uxc);
> +	return ret;
> +}
> +
> +static int lt9611uxc_get_edid_block(void *data, u8 *buf, unsigned int block, size_t len)
> +{
> +	struct lt9611uxc *lt9611uxc = data;
> +	int ret;
> +
> +	if (len > EDID_BLOCK_SIZE)
> +		return -EINVAL;
> +
> +	if (block >= EDID_NUM_BLOCKS)
> +		return -EINVAL;
> +
> +	if (block == 0) {
> +		ret = lt9611uxc_read_edid(lt9611uxc);
> +		if (ret) {
> +			dev_err(lt9611uxc->dev, "edid read failed\n");
> +			return ret;
> +		}
> +	}
> +
> +	memcpy(buf, lt9611uxc->edid_buf + block * EDID_BLOCK_SIZE, len);
> +	return 0;
> +};
> +
> +static struct edid *lt9611uxc_bridge_get_edid(struct drm_bridge *bridge,
> +					      struct drm_connector *connector)
> +{
> +	struct lt9611uxc *lt9611uxc = bridge_to_lt9611uxc(bridge);
> +
> +	return drm_do_get_edid(connector, lt9611uxc_get_edid_block, lt9611uxc);
> +}
> +
> +static const struct drm_bridge_funcs lt9611uxc_bridge_funcs = {
> +	.attach = lt9611uxc_bridge_attach,
> +	.detach = lt9611uxc_bridge_detach,
> +	.mode_valid = lt9611uxc_bridge_mode_valid,
> +	.post_disable = lt9611uxc_bridge_post_disable,
> +	.mode_set = lt9611uxc_bridge_mode_set,
> +	.detect = lt9611uxc_bridge_detect,
> +	.get_modes = lt9611uxc_bridge_get_modes,
> +	.get_edid = lt9611uxc_bridge_get_edid,
> +};
> +
> +static int lt9611uxc_parse_dt(struct device *dev,
> +			      struct lt9611uxc *lt9611uxc)
> +{
> +	lt9611uxc->timings = of_get_display_timings(dev->of_node);
> +	if (!lt9611uxc->timings)
> +		dev_info(dev, "no display timings provided\n");
> +
> +	lt9611uxc->dsi0_node = of_graph_get_remote_node(dev->of_node, 0, -1);
> +	if (!lt9611uxc->dsi0_node) {
> +		dev_err(lt9611uxc->dev, "failed to get remote node for primary dsi\n");
> +		return -ENODEV;
> +	}
> +
> +	lt9611uxc->dsi1_node = of_graph_get_remote_node(dev->of_node, 1, -1);
> +
> +	return 0;
> +}
> +
> +static int lt9611uxc_gpio_init(struct lt9611uxc *lt9611uxc)
> +{
> +	struct device *dev = lt9611uxc->dev;
> +
> +	lt9611uxc->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
> +	if (IS_ERR(lt9611uxc->reset_gpio)) {
> +		dev_err(dev, "failed to acquire reset gpio\n");
> +		return PTR_ERR(lt9611uxc->reset_gpio);
> +	}
> +
> +	lt9611uxc->enable_gpio = devm_gpiod_get_optional(dev, "enable", GPIOD_OUT_LOW);
> +	if (IS_ERR(lt9611uxc->enable_gpio)) {
> +		dev_err(dev, "failed to acquire enable gpio\n");
> +		return PTR_ERR(lt9611uxc->enable_gpio);
> +	}
> +
> +	return 0;
> +}
> +
> +static int lt9611uxc_read_device_rev(struct lt9611uxc *lt9611uxc)
> +{
> +	unsigned int rev0, rev1, rev2;
> +	int ret;
> +
> +	lt9611uxc_lock(lt9611uxc);
> +
> +	ret = regmap_read(lt9611uxc->regmap, 0x8100, &rev0);
> +	ret |= regmap_read(lt9611uxc->regmap, 0x8101, &rev1);
> +	ret |= regmap_read(lt9611uxc->regmap, 0x8102, &rev2);
> +	if (ret)
> +		dev_err(lt9611uxc->dev, "failed to read revision: %d\n", ret);
> +	else
> +		dev_info(lt9611uxc->dev, "LT9611 revision: 0x%02x.%02x.%02x\n", rev0, rev1, rev2);
> +
> +	lt9611uxc_unlock(lt9611uxc);
> +
> +	return ret;
> +}
> +
> +static int lt9611uxc_read_version(struct lt9611uxc *lt9611uxc)
> +{
> +	unsigned int rev;
> +	int ret;
> +
> +	lt9611uxc_lock(lt9611uxc);
> +
> +	ret = regmap_read(lt9611uxc->regmap, 0xb021, &rev);
> +	if (ret)
> +		dev_err(lt9611uxc->dev, "failed to read revision: %d\n", ret);
> +	else
> +		dev_info(lt9611uxc->dev, "LT9611 version: 0x%02x\n", rev);
> +
> +	lt9611uxc_unlock(lt9611uxc);
> +
> +	return ret < 0 ? ret : rev;
> +}
> +
> +static int lt9611uxc_hdmi_hw_params(struct device *dev, void *data,
> +				    struct hdmi_codec_daifmt *fmt,
> +				    struct hdmi_codec_params *hparms)
> +{
> +	/*
> +	 * LT9611UXC will automatically detect rate and sample size, so no need
> +	 * to setup anything here.
> +	 */
> +	return 0;
> +}
> +
> +static void lt9611uxc_audio_shutdown(struct device *dev, void *data)
> +{
> +}
> +
> +static int lt9611uxc_hdmi_i2s_get_dai_id(struct snd_soc_component *component,
> +					 struct device_node *endpoint)
> +{
> +	struct of_endpoint of_ep;
> +	int ret;
> +
> +	ret = of_graph_parse_endpoint(endpoint, &of_ep);
> +	if (ret < 0)
> +		return ret;
> +
> +	/*
> +	 * HDMI sound should be located as reg = <2>
> +	 * Then, it is sound port 0
> +	 */
> +	if (of_ep.port == 2)
> +		return 0;
> +
> +	return -EINVAL;
> +}
> +
> +static const struct hdmi_codec_ops lt9611uxc_codec_ops = {
> +	.hw_params	= lt9611uxc_hdmi_hw_params,
> +	.audio_shutdown = lt9611uxc_audio_shutdown,
> +	.get_dai_id	= lt9611uxc_hdmi_i2s_get_dai_id,
> +};
Is an audio_startup() operation missing here?

> +
> +static int lt9611uxc_audio_init(struct device *dev, struct lt9611uxc *lt9611uxc)
> +{
> +	struct hdmi_codec_pdata codec_data = {
> +		.ops = &lt9611uxc_codec_ops,
> +		.max_i2s_channels = 2,
> +		.i2s = 1,
> +		.data = lt9611uxc,
> +	};
> +
> +	lt9611uxc->audio_pdev =
> +		platform_device_register_data(dev, HDMI_CODEC_DRV_NAME,
> +					      PLATFORM_DEVID_AUTO,
> +					      &codec_data, sizeof(codec_data));
> +
> +	return PTR_ERR_OR_ZERO(lt9611uxc->audio_pdev);
> +}
> +
> +static void lt9611uxc_audio_exit(struct lt9611uxc *lt9611uxc)
> +{
> +	if (lt9611uxc->audio_pdev) {
> +		platform_device_unregister(lt9611uxc->audio_pdev);
> +		lt9611uxc->audio_pdev = NULL;
> +	}
> +}
> +
> +static int lt9611uxc_probe(struct i2c_client *client,
> +			   const struct i2c_device_id *id)
> +{
> +	struct lt9611uxc *lt9611uxc;
> +	struct device *dev = &client->dev;
> +	int ret;
> +
> +	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
> +		dev_err(dev, "device doesn't support I2C\n");
> +		return -ENODEV;
> +	}
> +
> +	lt9611uxc = devm_kzalloc(dev, sizeof(*lt9611uxc), GFP_KERNEL);
> +	if (!lt9611uxc)
> +		return -ENOMEM;
> +
> +	lt9611uxc->dev = &client->dev;
> +	lt9611uxc->client = client;
> +	mutex_init(&lt9611uxc->ocm_lock);
> +
> +	lt9611uxc->regmap = devm_regmap_init_i2c(client, &lt9611uxc_regmap_config);
> +	if (IS_ERR(lt9611uxc->regmap)) {
> +		dev_err(lt9611uxc->dev, "regmap i2c init failed\n");
> +		return PTR_ERR(lt9611uxc->regmap);
> +	}
> +
> +	ret = lt9611uxc_parse_dt(&client->dev, lt9611uxc);
> +	if (ret) {
> +		dev_err(dev, "failed to parse device tree\n");
> +		return ret;
> +	}
> +
> +	ret = lt9611uxc_gpio_init(lt9611uxc);
> +	if (ret < 0)
> +		goto err_of_put;
> +
> +	ret = lt9611uxc_regulator_init(lt9611uxc);
> +	if (ret < 0)
> +		goto err_of_put;
> +
> +	lt9611uxc_assert_5v(lt9611uxc);
> +
> +	ret = lt9611uxc_regulator_enable(lt9611uxc);
> +	if (ret)
> +		goto err_of_put;
> +
> +	lt9611uxc_reset(lt9611uxc);
> +
> +	ret = lt9611uxc_read_device_rev(lt9611uxc);
> +	if (ret) {
> +		dev_err(dev, "failed to read chip rev\n");
> +		goto err_disable_regulators;
> +	}
> +
> +	ret = lt9611uxc_read_version(lt9611uxc);
> +	if (ret < 0) {
> +		dev_err(dev, "failed to read FW version\n");
> +		goto err_disable_regulators;
> +	} else if (ret == 0) {
> +		dev_err(dev, "FW version 0, FW update not supported\n");
> +		ret = -EOPNOTSUPP;
> +		goto err_disable_regulators;
> +	} else if (ret < 0x40) {
> +		dev_info(dev, "FW version 0x%x, HPD not supported\n", ret);
> +	} else {
> +		lt9611uxc->hpd_supported = true;
> +	}
> +
> +	ret = devm_request_threaded_irq(dev, client->irq, NULL,
> +					lt9611uxc_irq_thread_handler,
> +					IRQF_ONESHOT, "lt9611uxc", lt9611uxc);
> +	if (ret) {
> +		dev_err(dev, "failed to request irq\n");
> +		goto err_disable_regulators;
> +	}
> +
> +	i2c_set_clientdata(client, lt9611uxc);
> +
> +	lt9611uxc->bridge.funcs = &lt9611uxc_bridge_funcs;
> +	lt9611uxc->bridge.of_node = client->dev.of_node;
> +	lt9611uxc->bridge.ops = DRM_BRIDGE_OP_DETECT;
> +	if (lt9611uxc->timings)
> +		lt9611uxc->bridge.ops |= DRM_BRIDGE_OP_MODES;
> +	else
> +		lt9611uxc->bridge.ops |= DRM_BRIDGE_OP_EDID;
> +	if (lt9611uxc->hpd_supported)
> +		lt9611uxc->bridge.ops |= DRM_BRIDGE_OP_HPD;
> +	lt9611uxc->bridge.type = DRM_MODE_CONNECTOR_HDMIA;
> +
> +	drm_bridge_add(&lt9611uxc->bridge);
> +
> +	return lt9611uxc_audio_init(dev, lt9611uxc);
> +
> +err_disable_regulators:
> +	regulator_bulk_disable(ARRAY_SIZE(lt9611uxc->supplies), lt9611uxc->supplies);
> +
> +err_of_put:
> +	of_node_put(lt9611uxc->dsi1_node);
> +	of_node_put(lt9611uxc->dsi0_node);
> +
> +	return ret;
> +}
> +
> +static int lt9611uxc_remove(struct i2c_client *client)
> +{
> +	struct lt9611uxc *lt9611uxc = i2c_get_clientdata(client);
> +
> +	disable_irq(client->irq);
> +	lt9611uxc_audio_exit(lt9611uxc);
> +	drm_bridge_remove(&lt9611uxc->bridge);
> +
> +	mutex_destroy(&lt9611uxc->ocm_lock);
> +
> +	regulator_bulk_disable(ARRAY_SIZE(lt9611uxc->supplies), lt9611uxc->supplies);
> +
> +	of_node_put(lt9611uxc->dsi1_node);
> +	of_node_put(lt9611uxc->dsi0_node);
> +
> +	return 0;
> +}
> +
> +static struct i2c_device_id lt9611uxc_id[] = {
> +	{ "lontium,lt9611uxc", 0 },
> +	{}
> +};
> +
> +static const struct of_device_id lt9611uxc_match_table[] = {
> +	{ .compatible = "lontium,lt9611uxc" },
> +	{ }
	{ /* sentinel */ },
> +};
> +MODULE_DEVICE_TABLE(of, lt9611uxc_match_table);
> +
> +static struct i2c_driver lt9611uxc_driver = {
> +	.driver = {
> +		.name = "lt9611uxc",
> +		.of_match_table = lt9611uxc_match_table,
> +	},
> +	.probe = lt9611uxc_probe,
> +	.remove = lt9611uxc_remove,
> +	.id_table = lt9611uxc_id,
> +};
> +module_i2c_driver(lt9611uxc_driver);
> +
> +MODULE_LICENSE("GPL v2");
> -- 
> 2.28.0
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