Re: [RFC PATCH v3 9/9] ipu3-cio2: Add functionality allowing software_node connections to sensors on platforms designed for Windows

[Dan Scally]

On 24/10/2020 02:24, Laurent Pinchart wrote:
> Hi Daniel,
>
> Thank you for the patch.
Thank you for reviewing it - very helpful comments
>
> On Mon, Oct 19, 2020 at 11:59:03PM +0100, Daniel Scally wrote:
>> Currently on platforms designed for Windows, connections between CIO2 and
>> sensors are not properly defined in DSDT. This patch extends the ipu3-cio2
>> driver to compensate by building software_node connections, parsing the
>> connection properties from the sensor's SSDB buffer.
>>
>> Suggested-by: Jordan Hand <jorhand@xxxxxxxxxxxxxxxxxxx>
>> Signed-off-by: Daniel Scally <djrscally@xxxxxxxxx>
>> ---
>> Changes in v3:
>> 	- Rather than overwriting the device's primary fwnode, we now
>> 	simply assign a secondary. Some of the preceding patches alter the
>> 	existing driver code and v4l2 framework to allow for that.
>> 	- Rather than reprobe() the sensor after connecting the devices in
>> 	cio2-bridge we create the software_nodes right away. In this case,
>> 	sensor drivers will have to defer probing until they detect that a
>> 	fwnode graph is connecting them to the CIO2 device.
>> 	- Error paths in connect_supported_devices() moved outside the
>> 	loop
>> 	- Replaced pr_*() with dev_*() throughout
>> 	- Moved creation of software_node / property_entry arrays to stack
>> 	- A lot of formatting changes.
>>
>>  MAINTAINERS                                   |   1 +
>>  drivers/media/pci/intel/ipu3/Kconfig          |  18 +
>>  drivers/media/pci/intel/ipu3/Makefile         |   3 +-
>>  drivers/media/pci/intel/ipu3/cio2-bridge.c    | 327 ++++++++++++++++++
>>  drivers/media/pci/intel/ipu3/cio2-bridge.h    |  94 +++++
>>  drivers/media/pci/intel/ipu3/ipu3-cio2-main.c |  21 ++
>>  drivers/media/pci/intel/ipu3/ipu3-cio2.h      |   9 +
>>  7 files changed, 472 insertions(+), 1 deletion(-)
>>  create mode 100644 drivers/media/pci/intel/ipu3/cio2-bridge.c
>>  create mode 100644 drivers/media/pci/intel/ipu3/cio2-bridge.h
>>
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index 5d768d5ad..4c9c646c7 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -8848,6 +8848,7 @@ INTEL IPU3 CSI-2 CIO2 DRIVER
>>  M:	Yong Zhi <yong.zhi@xxxxxxxxx>
>>  M:	Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
>>  M:	Bingbu Cao <bingbu.cao@xxxxxxxxx>
>> +M:	Dan Scally <djrscally@xxxxxxxxx>
>>  R:	Tianshu Qiu <tian.shu.qiu@xxxxxxxxx>
>>  L:	linux-media@xxxxxxxxxxxxxxx
>>  S:	Maintained
>> diff --git a/drivers/media/pci/intel/ipu3/Kconfig b/drivers/media/pci/intel/ipu3/Kconfig
>> index 82d7f17e6..d14cbceae 100644
>> --- a/drivers/media/pci/intel/ipu3/Kconfig
>> +++ b/drivers/media/pci/intel/ipu3/Kconfig
>> @@ -16,3 +16,21 @@ config VIDEO_IPU3_CIO2
>>  	  Say Y or M here if you have a Skylake/Kaby Lake SoC with MIPI CSI-2
>>  	  connected camera.
>>  	  The module will be called ipu3-cio2.
>> +
>> +config CIO2_BRIDGE
>> +	bool "IPU3 CIO2 Sensors Bridge"
>> +	depends on VIDEO_IPU3_CIO2
>> +	help
>> +	  This extension provides an API for the ipu3-cio2 driver to create
>> +	  connections to cameras that are hidden in SSDB buffer in ACPI. It
>> +	  can be used to enable support for cameras in detachable / hybrid
>> +	  devices that ship with Windows.
>> +
>> +	  Say Y here if your device is a detachable / hybrid laptop that comes
>> +	  with Windows installed by the OEM, for example:
>> +
>> +	  	- Some Microsoft Surface models
>> +		- The Lenovo Miix line
>> +		- Dell 7285
>> +
>> +	  If in doubt, say N here.
>> diff --git a/drivers/media/pci/intel/ipu3/Makefile b/drivers/media/pci/intel/ipu3/Makefile
>> index b4e3266d9..933777e6e 100644
>> --- a/drivers/media/pci/intel/ipu3/Makefile
>> +++ b/drivers/media/pci/intel/ipu3/Makefile
>> @@ -1,4 +1,5 @@
>>  # SPDX-License-Identifier: GPL-2.0-only
>>  obj-$(CONFIG_VIDEO_IPU3_CIO2) += ipu3-cio2.o
>>  
>> -ipu3-cio2-y += ipu3-cio2-main.o
>> \ No newline at end of file
>> +ipu3-cio2-y += ipu3-cio2-main.o
>> +ipu3-cio2-$(CONFIG_CIO2_BRIDGE) += cio2-bridge.o
>> diff --git a/drivers/media/pci/intel/ipu3/cio2-bridge.c b/drivers/media/pci/intel/ipu3/cio2-bridge.c
>> new file mode 100644
>> index 000000000..bbe072f04
>> --- /dev/null
>> +++ b/drivers/media/pci/intel/ipu3/cio2-bridge.c
>> @@ -0,0 +1,327 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +// Author: Dan Scally <djrscally@xxxxxxxxx>
>> +#include <linux/acpi.h>
>> +#include <linux/device.h>
>> +#include <linux/fwnode.h>
>> +#include <linux/i2c.h>
>> +#include <linux/kernel.h>
>> +#include <linux/module.h>
>> +#include <linux/pci.h>
>> +#include <linux/property.h>
>> +#include <media/v4l2-subdev.h>
>> +
>> +#include "cio2-bridge.h"
>> +
>> +/*
>> + * Extend this array with ACPI Hardware ID's of devices known to be
>> + * working
>> + */
>> +static const char * const supported_devices[] = {
>> +	"INT33BE",
>> +	"OVTI2680",
>> +};
>> +
>> +static struct software_node cio2_hid_node = { CIO2_HID };
>> +
>> +static struct cio2_bridge bridge;
> While there shouldn't be more than one CIO2 instance, we try to develop
> drivers in a way that avoids global per-device variables. Could all this
> be allocated dynamically, with the pointer returned by
> cio2_bridge_build() and stored in the cio2_device structure ?
Yes, ok, I'll make that change.
>> +
>> +static const char * const port_names[] = {
>> +	"port0", "port1", "port2", "port3"
>> +};
>> +
>> +static const struct property_entry remote_endpoints[] = {
>> +	PROPERTY_ENTRY_REF("remote-endpoint", /* Sensor 0, Sensor Property */
>> +			   &bridge.sensors[0].swnodes[SWNODE_CIO2_ENDPOINT]),
>> +	PROPERTY_ENTRY_REF("remote-endpoint", /* Sensor 0, CIO2 Property */
>> +			   &bridge.sensors[0].swnodes[SWNODE_SENSOR_ENDPOINT]),
>> +	PROPERTY_ENTRY_REF("remote-endpoint",
>> +			   &bridge.sensors[1].swnodes[SWNODE_CIO2_ENDPOINT]),
>> +	PROPERTY_ENTRY_REF("remote-endpoint",
>> +			   &bridge.sensors[1].swnodes[SWNODE_SENSOR_ENDPOINT]),
>> +	PROPERTY_ENTRY_REF("remote-endpoint",
>> +			   &bridge.sensors[2].swnodes[SWNODE_CIO2_ENDPOINT]),
>> +	PROPERTY_ENTRY_REF("remote-endpoint",
>> +			   &bridge.sensors[2].swnodes[SWNODE_SENSOR_ENDPOINT]),
>> +	PROPERTY_ENTRY_REF("remote-endpoint",
>> +			   &bridge.sensors[3].swnodes[SWNODE_CIO2_ENDPOINT]),
>> +	PROPERTY_ENTRY_REF("remote-endpoint",
>> +			   &bridge.sensors[3].swnodes[SWNODE_SENSOR_ENDPOINT]),
>> +};
> For the same reason, I would move this to the sensor structure (with two
> property_entry per sensor). That will simplify the code below, avoiding
> indexing this array with bridge.n_sensors * 2.
I had some trouble with that which is why I ended up doing things this
way; I'll revisit it and see if I can resolve that.
>> +
>> +static int read_acpi_block(struct device *dev, char *id, void *data, u32 size)
> To avoid potential future namespace classes, I'd advise naming the
> functions with a cio2_bridge_ prefix, even the static ones.
>
> And maybe cio2_bridge_read_acpi_buffer(), as this function reads a
> buffer ?
Ack to both; and to the similar comments re: variable naming below.
>> +{
>> +	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
>> +	struct acpi_handle *handle;
>> +	union acpi_object *obj;
>> +	acpi_status status;
>> +	int ret;
>> +
>> +	handle = ACPI_HANDLE(dev);
>> +
>> +	status = acpi_evaluate_object(handle, id, NULL, &buffer);
>> +	if (ACPI_FAILURE(status))
>> +		return -ENODEV;
>> +
>> +	obj = buffer.pointer;
>> +	if (!obj) {
>> +		dev_err(dev, "Couldn't locate ACPI buffer\n");
>> +		return -ENODEV;
>> +	}
>> +
>> +	if (obj->type != ACPI_TYPE_BUFFER) {
>> +		dev_err(dev, "Couldn't read ACPI buffer\n");
>> +		ret = -ENODEV;
>> +		goto out_free_buff;
>> +	}
>> +
>> +	if (obj->buffer.length > size) {
>> +		dev_err(dev, "Given buffer is too small\n");
>> +		ret = -ENODEV;
>> +		goto out_free_buff;
>> +	}
>> +
>> +	memcpy(data, obj->buffer.pointer, obj->buffer.length);
>> +	ret = obj->buffer.length;
>> +
>> +out_free_buff:
>> +	kfree(buffer.pointer);
>> +	return ret;
>> +}
>> +
>> +static int get_acpi_ssdb_sensor_data(struct device *dev,
>> +				     struct sensor_bios_data *sensor)
>> +{
>> +	struct sensor_bios_data_packed sensor_data;
>> +	int ret;
>> +
>> +	ret = read_acpi_block(dev, "SSDB", &sensor_data, sizeof(sensor_data));
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	sensor->link = sensor_data.link;
>> +	sensor->lanes = sensor_data.lanes;
>> +	sensor->mclkspeed = sensor_data.mclkspeed;
>> +	sensor->degree = sensor_data.degree;
> How about storing a sensor_bios_data_packed inside sensor_bios_data ?
> That will avoid copying fields individually, with manual addition of
> extra fields as they become useful. Usage of the sensor_bios_data
> structure would turn from sensor->degree to sensor->ssdb.degree, which
> is slightly longer, but I think more maintainable.
Inside the struct sensor you mean (confusingly, the variable named
sensor here is _not_ of type struct sensor, which I acknowledge is plain
silly)? If so, agreed, I'll change it to that. That's also consistent
with what I'm doing with the equivalent struct for the PMIC's CLDB in
the regulator work so that makes sense anyway.
>> +
>> +	return 0;
>> +}
>> +
>> +static int create_fwnode_properties(struct sensor *sensor,
>> +				    struct sensor_bios_data *ssdb)
>> +{
>> +	struct property_entry *cio2_properties = sensor->cio2_properties;
>> +	struct property_entry *dev_properties = sensor->dev_properties;
>> +	struct property_entry *ep_properties = sensor->ep_properties;
>> +	int i;
> i never takes negative values, you can make it an unsigned int. Same for
> other occurrences below.
>
>> +
>> +	/* device fwnode properties */
>> +	memset(dev_properties, 0, sizeof(struct property_entry) * 3);
> I would memset() bridge to 0 in one go and avoid individual memsets. And
> if you allocate it with kzalloc() it will be initialized to 0.
Yep ok, I'll initialize the whole thing with kzalloc at the start then
>
>> +
>> +	dev_properties[0] = PROPERTY_ENTRY_U32("clock-frequency",
>> +					       ssdb->mclkspeed);
>> +	dev_properties[1] = PROPERTY_ENTRY_U8("rotation", ssdb->degree);
>> +
>> +	/* endpoint fwnode properties */
>> +	memset(ep_properties, 0, sizeof(struct property_entry) * 4);
>> +
>> +	sensor->data_lanes = kmalloc_array(ssdb->lanes, sizeof(u32),
>> +					   GFP_KERNEL);
> Given that there can't be more than 4 data lanes, how about turning
> data_lanes into an array with 4 entries, to avoid the dynamic allocation
> ? You will have to validate ssdb->lanes in connect_supported_devices(),
> to make sure not to overflow the array. This and the next function can
> then be turned into void functions.
OK - is that generally better then (I.E. avoiding dynamic allocation),
or just when the "wasted" memory is so small?
>
>> +
>> +	if (!sensor->data_lanes)
>> +		return -ENOMEM;
>> +
>> +	for (i = 0; i < ssdb->lanes; i++)
>> +		sensor->data_lanes[i] = i + 1;
>> +
>> +	ep_properties[0] = PROPERTY_ENTRY_U32("bus-type", 5);
>> +	ep_properties[1] = PROPERTY_ENTRY_U32_ARRAY_LEN("data-lanes",
>> +							sensor->data_lanes,
>> +							ssdb->lanes);
>> +	ep_properties[2] = remote_endpoints[(bridge.n_sensors * 2) + ENDPOINT_SENSOR];
>> +
>> +	/* cio2 endpoint props */
>> +	memset(cio2_properties, 0, sizeof(struct property_entry) * 3);
>> +
>> +	cio2_properties[0] = PROPERTY_ENTRY_U32_ARRAY_LEN("data-lanes",
>> +							  sensor->data_lanes,
>> +							  ssdb->lanes);
>> +	cio2_properties[1] = remote_endpoints[(bridge.n_sensors * 2) + ENDPOINT_CIO2];
>> +
>> +	return 0;
>> +}
>> +
>> +static int create_connection_swnodes(struct sensor *sensor,
>> +				     struct sensor_bios_data *ssdb)
>> +{
>> +	struct software_node *nodes = sensor->swnodes;
>> +
>> +	memset(nodes, 0, sizeof(struct software_node) * 6);
>> +
>> +	nodes[SWNODE_SENSOR_HID] = NODE_SENSOR(sensor->name,
>> +					       sensor->dev_properties);
>> +	nodes[SWNODE_SENSOR_PORT] = NODE_PORT("port0",
>> +					      &nodes[SWNODE_SENSOR_HID]);
>> +	nodes[SWNODE_SENSOR_ENDPOINT] = NODE_ENDPOINT("endpoint0",
>> +						      &nodes[SWNODE_SENSOR_PORT],
>> +						      sensor->ep_properties);
>> +	nodes[SWNODE_CIO2_PORT] = NODE_PORT(port_names[ssdb->link],
>> +					    &cio2_hid_node);
>> +	nodes[SWNODE_CIO2_ENDPOINT] = NODE_ENDPOINT("endpoint0",
>> +						    &nodes[SWNODE_CIO2_PORT],
>> +						    sensor->cio2_properties);
>> +
>> +	return 0;
>> +}
>> +
>> +static void cio2_bridge_unregister_sensors(void)
>> +{
>> +	struct sensor *sensor;
>> +	int i;
>> +
>> +	for (i = 0; i < bridge.n_sensors; i++) {
>> +		sensor = &bridge.sensors[i];
>> +
>> +		software_node_unregister_nodes_reverse(sensor->swnodes);
>> +
>> +		kfree(sensor->data_lanes);
>> +
>> +		put_device(sensor->dev);
>> +		acpi_dev_put(sensor->adev);
>> +	}
>> +}
>> +
>> +static int connect_supported_devices(struct pci_dev *cio2)
>> +{
>> +	struct sensor_bios_data ssdb;
>> +	struct fwnode_handle *fwnode;
>> +	struct acpi_device *adev;
>> +	struct sensor *sensor;
>> +	struct device *dev;
>> +	int i, ret;
>> +
>> +	ret = 0;
> You can initialize ret to 0 when declaring the variable.
Is that ok on the same like as i's declaration, or should I split them?
>
>> +	for (i = 0; i < ARRAY_SIZE(supported_devices); i++) {
>> +		adev = acpi_dev_get_first_match_dev(supported_devices[i], NULL, -1);
> What if there are multiple sensor of the same model ?

Hmm, yeah, that would be a bit of a pickle. I guess the newer
smartphones have multiple sensors on the back, which I presume are the
same model. So that will probably crop up at some point. How about
instead I use bus_for_each_dev() and in the applied function check if
the _HID is in the supported list?

>
>> +		if (!adev)
>> +			continue;
>> +
> Does acpi_dev_get_first_match_dev() skip disabled devices (as reported
> by _STA) ?
Yes.
>> +		dev = bus_find_device_by_acpi_dev(&i2c_bus_type, adev);
>> +		if (!dev) {
>> +			ret = -EPROBE_DEFER;
>> +			goto err_rollback;
>> +		}
>> +
>> +		sensor = &bridge.sensors[bridge.n_sensors];
>> +		sensor->dev = dev;
>> +		sensor->adev = adev;
>> +
>> +		snprintf(sensor->name, ACPI_ID_LEN, "%s",
>> +			 supported_devices[i]);
> How about strlcpy() ?
Sure
>> +
>> +		ret = get_acpi_ssdb_sensor_data(dev, &ssdb);
>> +		if (ret)
>> +			goto err_free_dev;
>> +
>> +		ret = create_fwnode_properties(sensor, &ssdb);
>> +		if (ret)
>> +			goto err_free_dev;
>> +
>> +		ret = create_connection_swnodes(sensor, &ssdb);
>> +		if (ret)
>> +			goto err_free_dev;
>> +
>> +		ret = software_node_register_nodes(sensor->swnodes);
>> +		if (ret)
>> +			goto err_free_dev;
>> +
>> +		fwnode = software_node_fwnode(&sensor->swnodes[SWNODE_SENSOR_HID]);
>> +		if (!fwnode) {
>> +			ret = -ENODEV;
>> +			goto err_free_swnodes;
>> +		}
>> +
>> +		set_secondary_fwnode(dev, fwnode);
> I wonder if we could avoid depending on the I2C device being created by
> getting the fwnode from adev, and setting ->secondary manually. adev
> would need to be passed to get_acpi_ssdb_sensor_data() instead of dev.
Let me try that; I initially wanted to do
set_secondary_fwnode(&adev->dev, fwnode) to avoid depending on the I2C
dev being created but it turns out &adev->dev isn't the same pointer. I
shall try it and see.
>
>> +
>> +		dev_info(&cio2->dev, "Found supported device %s\n",
>> +			 supported_devices[i]);
>> +
>> +		bridge.n_sensors++;
>> +		continue;
>> +	}
>> +
>> +	return ret;
>> +
>> +err_free_swnodes:
>> +	software_node_unregister_nodes_reverse(sensor->swnodes);
>> +err_free_dev:
>> +	put_device(dev);
>> +err_rollback:
>> +	acpi_dev_put(adev);
> I think you'll leak sensor->data_lanes here. It won't be a problem if
> you don't allocate it manually, as proposed above. I however wonder if
> error handling couldn't be simplified by increasing bridge.n_sensors
> earlier, and skipping cleanup in cio2_bridge_unregister_sensors() for
> the fields that haven't been initialized (for instance kfree() is a
> no-op on NULL pointers, so that's already handled).
Errrr the only sticky bit there is the desire _not_ to unwind all the
sensors if it managed to successfully connect one of them; if I'm just
calling cio2_bridge_unregister_sensors() on any error then a failure for
one sensor will result in no working cameras, where this way at least
one of them might be available.
>
>> +
>> +	/*
>> +	 * If an iteration of this loop results in -EPROBE_DEFER then
>> +	 * we need to roll back any sensors that were successfully
>> +	 * registered. Any other error and we'll skip that step, as
>> +	 * it seems better to have one successfully connected sensor.
>> +	 */
>> +
>> +	if (ret == -EPROBE_DEFER)
>> +		cio2_bridge_unregister_sensors();
>> +
>> +	return ret;
>> +}
>> +
>> +int cio2_bridge_build(struct pci_dev *cio2)
>> +{
>> +	struct fwnode_handle *fwnode;
>> +	int ret;
>> +
>> +	pci_dev_get(cio2);
>> +
>> +	ret = software_node_register(&cio2_hid_node);
>> +	if (ret < 0) {
>> +		dev_err(&cio2->dev, "Failed to register the CIO2 HID node\n");
>> +		goto err_put_cio2;
>> +	}
>> +
>> +	ret = connect_supported_devices(cio2);
>> +	if (ret == -EPROBE_DEFER)
>> +		goto err_unregister_cio2;
>> +
>> +	if (bridge.n_sensors == 0) {
>> +		ret = -EPROBE_DEFER;
>> +		goto err_unregister_cio2;
>> +	}
>> +
>> +	dev_info(&cio2->dev, "Connected %d cameras\n", bridge.n_sensors);
>> +
>> +	fwnode = software_node_fwnode(&cio2_hid_node);
>> +	if (!fwnode) {
>> +		dev_err(&cio2->dev,
>> +			"Error getting fwnode from cio2 software_node\n");
>> +		ret = -ENODEV;
>> +		goto err_unregister_sensors;
>> +	}
>> +
>> +	set_secondary_fwnode(&cio2->dev, fwnode);
>> +
>> +	return 0;
>> +
>> +err_unregister_sensors:
>> +	cio2_bridge_unregister_sensors();
>> +err_unregister_cio2:
>> +	software_node_unregister(&cio2_hid_node);
>> +err_put_cio2:
>> +	pci_dev_put(cio2);
>> +
>> +	return ret;
>> +}
>> +
>> +void cio2_bridge_burn(struct pci_dev *cio2)
> Interesting function name :-) I like the creativity, but I think
> consistency with the rest of the kernel code should unfortunately be
> favoured.

Heh yep - already changed to _init/_clean per Andy's comments. Couldn't
resist the pun!

>> +	struct sensor sensors[MAX_CONNECTED_DEVICES];
>> +};
>> +
>> +/* Data representation as it is in ACPI SSDB buffer */
>> +struct sensor_bios_data_packed {
> Similarly as above, I'd use a cio2_ prefix, and I think you can drop the
> _packed suffix. How about naming it cio2_sensor_ssdb_data (or even just
> cio2_sensor_ssdb) to make it clearer that it contains the SSDB data ?
Already done (well, sensor_ssdb currently) to keep consistent with
struct pmic_cldb that was introduced. I'll add the cio2 prefix.
>
>> +	u8 version;
>> +	u8 sku;
>> +	u8 guid_csi2[16];
>> +	u8 devfunction;
>> +	u8 bus;
>> +	u32 dphylinkenfuses;
>> +	u32 clockdiv;
>> +	u8 link;
>> +	u8 lanes;
>> +	u32 csiparams[10];
>> +	u32 maxlanespeed;
>> +	u8 sensorcalibfileidx;
>> +	u8 sensorcalibfileidxInMBZ[3];
>> +	u8 romtype;
>> +	u8 vcmtype;
>> +	u8 platforminfo;
>> +	u8 platformsubinfo;
>> +	u8 flash;
>> +	u8 privacyled;
>> +	u8 degree;
>> +	u8 mipilinkdefined;
>> +	u32 mclkspeed;
>> +	u8 controllogicid;
>> +	u8 reserved1[3];
>> +	u8 mclkport;
>> +	u8 reserved2[13];
>> +} __packed__;
>> +
>> +/* Fields needed by bridge driver */
>> +struct sensor_bios_data {
> And cio2_sensor_data ?
Ack
>
>> +	struct device *dev;
>> +	u8 link;
>> +	u8 lanes;
>> +	u8 degree;
>> +	u32 mclkspeed;
>> +};
>> +
>> +#endif
>> diff --git a/drivers/media/pci/intel/ipu3/ipu3-cio2-main.c b/drivers/media/pci/intel/ipu3/ipu3-cio2-main.c
>> index f68ef0f6b..827457110 100644
>> --- a/drivers/media/pci/intel/ipu3/ipu3-cio2-main.c
>> +++ b/drivers/media/pci/intel/ipu3/ipu3-cio2-main.c
>> @@ -1715,9 +1715,27 @@ static void cio2_queues_exit(struct cio2_device *cio2)
>>  static int cio2_pci_probe(struct pci_dev *pci_dev,
>>  			  const struct pci_device_id *id)
>>  {
>> +	struct fwnode_handle *endpoint;
>>  	struct cio2_device *cio2;
>>  	int r;
>>  
>> +	/*
>> +	 * On some platforms no connections to sensors are defined in firmware,
>> +	 * if the device has no endpoints then we can try to build those as
>> +	 * software_nodes parsed from SSDB.
>> +	 *
>> +	 * This may EPROBE_DEFER if supported devices are found defined in ACPI
>> +	 * but not yet ready for use (either not attached to the i2c bus yet,
>> +	 * or not done probing themselves).
> Why do we need for the I2C devices to be probed, isn't it enough to have
> them created ?
Ooops  - a relic of the prior version that I missed out when cleaning up
- I'll fix that
> No need for an extra indentation level, neither here, not below.
> NO need for this blank line.
Both fixed - thanks very much