Re: [PATCH 13/18] ipu3-cio2: Add functionality allowing software_node connections to sensors on platforms designed for Windows

Laurent Pinchart
2020-11-30T17:11:04Z

Hi Daniel,

Thank you for the patch.

On Mon, Nov 30, 2020 at 01:31:24PM +0000, 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@linux.microsoft.com>
> Signed-off-by: Daniel Scally <djrscally@gmail.com>
> ---
> Changes since RFC v3:
>
> - Removed almost all global variables, dynamically allocated
> the cio2_bridge structure, plus a bunch of associated changes
> like
> - Added a new function to ipu3-cio2-main.c to check for an
> existing fwnode_graph before calling cio2_bridge_init()
> - Prefixed cio2_bridge_ to any variables and functions that
> lacked it
> - Assigned the new fwnode directly to the sensor's ACPI device
> fwnode as secondary. This removes the requirement to delay until
> the I2C devices are instantiated before ipu3-cio2 can probe, but
> it has a side effect, which is that those devices then grab a ref
> to the new software_node. This effectively prevents us from
> unloading the driver, because we can't free the memory that they
> live in whilst the device holds a reference to them. The work
> around at the moment is to _not_ unregister the software_nodes
> when ipu3-cio2 is unloaded; this becomes a one-time 'patch', that
> is simply skipped if the module is reloaded.
> - Moved the sensor's SSDB struct to be a member of cio2_sensor
> - Replaced ints with unsigned ints where appropriate
> - Iterated over all ACPI devices of a matching _HID rather than
> just the first to ensure we handle a device with multiple sensors
> of the same model.
>
> MAINTAINERS | 1 +
> drivers/media/pci/intel/ipu3/Kconfig | 18 ++
> drivers/media/pci/intel/ipu3/Makefile | 1 +
> drivers/media/pci/intel/ipu3/cio2-bridge.c | 260 ++++++++++++++++++
> drivers/media/pci/intel/ipu3/cio2-bridge.h | 108 ++++++++
> drivers/media/pci/intel/ipu3/ipu3-cio2-main.c | 27 ++
> drivers/media/pci/intel/ipu3/ipu3-cio2.h | 6 +
> 7 files changed, 421 insertions(+)
> 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 9702b886d6a4..188559a0a610 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -8927,6 +8927,7 @@ INTEL IPU3 CSI-2 CIO2 DRIVER
> M: Yong Zhi <yong.zhi@intel.com>
> M: Sakari Ailus <sakari.ailus@linux.intel.com>
> M: Bingbu Cao <bingbu.cao@intel.com>
> +M: Dan Scally <djrscally@gmail.com>
> R: Tianshu Qiu <tian.shu.qiu@intel.com>
> L: linux-media@vger.kernel.org
> S: Maintained
> diff --git a/drivers/media/pci/intel/ipu3/Kconfig b/drivers/media/pci/intel/ipu3/Kconfig
> index 82d7f17e6a02..2b3350d042be 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:
> +
> + - Microsoft Surface models (except Surface Pro 3)
> + - The Lenovo Miix line (for example the 510, 520, 710 and 720)
> + - 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 429d516452e4..933777e6ea8a 100644
> --- a/drivers/media/pci/intel/ipu3/Makefile
> +++ b/drivers/media/pci/intel/ipu3/Makefile
> @@ -2,3 +2,4 @@
> obj-$(CONFIG_VIDEO_IPU3_CIO2) += ipu3-cio2.o
>
> ipu3-cio2-y += ipu3-cio2-main.o
> +ipu3-cio2-$(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 000000000000..fd3f8ba07274
> --- /dev/null
> +++ b/drivers/media/pci/intel/ipu3/cio2-bridge.c
> @@ -0,0 +1,260 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Author: Dan Scally <djrscally@gmail.com> */

Could you please add a blank line here ?

> +#include <linux/acpi.h>
> +#include <linux/device.h>
> +#include <linux/i2c.h>

Is this header needed ?

> +#include <linux/kernel.h>
> +#include <linux/module.h>

And this one ?

> +#include <linux/pci.h>
> +#include <linux/property.h>
> +#include <media/v4l2-subdev.h>

And this one ?

> +
> +#include "cio2-bridge.h"
> +
> +/*
> + * Extend this array with ACPI Hardware ID's of devices known to be working.
> + * Do not add a HID for a sensor that is not actually supported.
> + */
> +static const char * const cio2_supported_devices[] = {

Maybe cio2_supported_sensors ?

> + "INT33BE",
> + "OVTI2680",
> +};
> +
> +static int cio2_bridge_read_acpi_buffer(struct acpi_device *adev, char *id,
> + void *data, u32 size)
> +{
> + struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
> + union acpi_object *obj;
> + acpi_status status;
> + int ret;
> +
> + status = acpi_evaluate_object(adev->handle, id, NULL, &buffer);
> + if (ACPI_FAILURE(status))
> + return -ENODEV;
> +
> + obj = buffer.pointer;
> + if (!obj) {
> + dev_err(&adev->dev, "Couldn't locate ACPI buffer\n");
> + return -ENODEV;
> + }
> +
> + if (obj->type != ACPI_TYPE_BUFFER) {
> + dev_err(&adev->dev, "Not an ACPI buffer\n");
> + ret = -ENODEV;
> + goto out_free_buff;
> + }
> +
> + if (obj->buffer.length > size) {
> + dev_err(&adev->dev, "Given buffer is too small\n");
> + ret = -EINVAL;
> + 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 void cio2_bridge_init_property_names(struct cio2_sensor *sensor)
> +{
> + strcpy(sensor->prop_names.clock_frequency, "clock-frequency");
> + strcpy(sensor->prop_names.rotation, "rotation");
> + strcpy(sensor->prop_names.bus_type, "bus-type");
> + strcpy(sensor->prop_names.data_lanes, "data-lanes");
> + strcpy(sensor->prop_names.remote_endpoint, "remote-endpoint");

This is a bit fragile, as there's no len check. How about the following
?
static const struct cio2_property_names prop_names = {
.clock_frequency = "clock-frequency",
.rotation = "rotation",
.bus_type = "bus-type",
.data_lanes = "data-lanes",
.remote_endpoint = "remote-endpoint",
};

static void cio2_bridge_init_property_names(struct cio2_sensor *sensor)
{
sensor->prop_names = prop_names;
}

This shoudl generate a compilation warning if the string is too long.

You could even inline that line in
cio2_bridge_create_fwnode_properties().

> +}
> +
> +static void cio2_bridge_create_fwnode_properties(struct cio2_sensor *sensor)
> +{
> + unsigned int i;
> +
> + cio2_bridge_init_property_names(sensor);
> +
> + for (i = 0; i < 4; i++)
> + sensor->data_lanes[i] = i + 1;

Is there no provision in the SSDB for data lane remapping ?

> +
> + /*
> + * Can't use PROPERTY_ENTRY_REF because it creates a new variable to
> + * point to, which doesn't survive the function.
> + */
> + sensor->local_ref[0] = (struct software_node_ref_args){
> + .node = &sensor->swnodes[SWNODE_CIO2_ENDPOINT]
> + };

I'd remove one tab here. Or just write

sensor->local_ref[0].node = &sensor->swnodes[SWNODE_CIO2_ENDPOINT];

> + sensor->remote_ref[0] = (struct software_node_ref_args){
> + .node = &sensor->swnodes[SWNODE_SENSOR_ENDPOINT]
> + };
> +
> + sensor->dev_properties[0] = PROPERTY_ENTRY_U32(sensor->prop_names.clock_frequency,
> + sensor->ssdb.mclkspeed);
> + sensor->dev_properties[1] = PROPERTY_ENTRY_U8(sensor->prop_names.rotation,
> + sensor->ssdb.degree);
> +
> + sensor->ep_properties[0] = PROPERTY_ENTRY_U32(sensor->prop_names.bus_type, 5);
> + sensor->ep_properties[1] = PROPERTY_ENTRY_U32_ARRAY_LEN(sensor->prop_names.data_lanes,
> + sensor->data_lanes,
> + sensor->ssdb.lanes);
> + sensor->ep_properties[2] = PROPERTY_ENTRY_REF_ARRAY(sensor->prop_names.remote_endpoint,
> + sensor->local_ref);
> +
> + sensor->cio2_properties[0] = PROPERTY_ENTRY_U32_ARRAY_LEN(sensor->prop_names.data_lanes,
> + sensor->data_lanes,
> + sensor->ssdb.lanes);
> + sensor->cio2_properties[1] = PROPERTY_ENTRY_REF_ARRAY(sensor->prop_names.remote_endpoint,
> + sensor->remote_ref);
> +}
> +
> +static void cio2_bridge_init_swnode_names(struct cio2_sensor *sensor)
> +{
> + snprintf(sensor->node_names.remote_port, 6, "port%u", sensor->ssdb.link);
> + strcpy(sensor->node_names.port, "port0");
> + strcpy(sensor->node_names.endpoint, "endpoint0");
> +}
> +
> +static void cio2_bridge_create_connection_swnodes(struct cio2_bridge *bridge,
> + struct cio2_sensor *sensor)
> +{
> + struct software_node *nodes = sensor->swnodes;
> +
> + cio2_bridge_init_swnode_names(sensor);
> +
> + nodes[SWNODE_SENSOR_HID] = NODE_SENSOR(sensor->name,
> + sensor->dev_properties);
> + nodes[SWNODE_SENSOR_PORT] = NODE_PORT(sensor->node_names.port,
> + &nodes[SWNODE_SENSOR_HID]);
> + nodes[SWNODE_SENSOR_ENDPOINT] = NODE_ENDPOINT(sensor->node_names.endpoint,
> + &nodes[SWNODE_SENSOR_PORT],
> + sensor->ep_properties);
> + nodes[SWNODE_CIO2_PORT] = NODE_PORT(sensor->node_names.remote_port,
> + &bridge->cio2_hid_node);
> + nodes[SWNODE_CIO2_ENDPOINT] = NODE_ENDPOINT(sensor->node_names.endpoint,
> + &nodes[SWNODE_CIO2_PORT],
> + sensor->cio2_properties);
> +}
> +
> +static void cio2_bridge_unregister_sensors(struct cio2_bridge *bridge)
> +{
> + struct cio2_sensor *sensor;
> + unsigned int i;
> +
> + for (i = 0; i < bridge->n_sensors; i++) {
> + sensor = &bridge->sensors[i];
> + software_node_unregister_nodes(sensor->swnodes);
> + acpi_dev_put(sensor->adev);
> + }
> +}
> +
> +static int cio2_bridge_connect_sensors(struct cio2_bridge *bridge)
> +{
> + struct fwnode_handle *fwnode;
> + struct cio2_sensor *sensor;
> + struct acpi_device *adev;
> + unsigned int i;
> + int ret = 0;
> +
> + for (i = 0; i < ARRAY_SIZE(cio2_supported_devices); i++) {
> + const char *this_device = cio2_supported_devices[i];

s/this_device/name/ (or sensor_name, ...) ?

> +
> + for_each_acpi_dev_match(adev, this_device, NULL, -1) {
> + if (!adev || !(adev->status.present && adev->status.enabled))

if (!adev || !adev->status.present || !adev->status.enabled))

may be a bit more readable. Does for_each_acpi_dev_match() return NULL
devices though ? If no, you could drop the !adev check. You may also be
able to drop the !present check, as I don't think ACPI allows !present
&& enabled.

> + continue;
> +
> + sensor = &bridge->sensors[bridge->n_sensors];
> + sensor->adev = adev;
> + strscpy(sensor->name, this_device, sizeof(sensor->name));
> +
> + ret = cio2_bridge_read_acpi_buffer(adev, "SSDB",
> + &sensor->ssdb,
> + sizeof(sensor->ssdb));
> + if (ret < 0)
> + goto err_put_adev;
> +
> + if (sensor->ssdb.lanes > 4) {
> + dev_err(&adev->dev,
> + "Number of lanes in SSDB is invalid\n");
> + goto err_put_adev;
> + }
> +
> + cio2_bridge_create_fwnode_properties(sensor);
> + cio2_bridge_create_connection_swnodes(bridge, sensor);
> +
> + ret = software_node_register_nodes(sensor->swnodes);
> + if (ret)
> + goto err_put_adev;
> +
> + fwnode = software_node_fwnode(&sensor->swnodes[SWNODE_SENSOR_HID]);
> + if (!fwnode) {
> + ret = -ENODEV;
> + goto err_free_swnodes;
> + }
> +
> + adev->fwnode.secondary = fwnode;
> +
> + dev_info(&bridge->cio2->dev,
> + "Found supported sensor %s\n",
> + acpi_dev_name(adev));
> +
> + bridge->n_sensors++;

We probably want a check here to avoid overflowing bridge->sensors. The
other option is to make bridge->sensors a struct list_head and allocate
sensors dynamically.

> + }
> + }
> +
> + return ret;
> +
> +err_free_swnodes:
> + software_node_unregister_nodes(sensor->swnodes);
> +err_put_adev:
> + acpi_dev_put(sensor->adev);
> +
> + return ret;
> +}
> +
> +int cio2_bridge_init(struct pci_dev *cio2)
> +{
> + struct device *dev = &cio2->dev;
> + struct fwnode_handle *fwnode;
> + struct cio2_bridge *bridge;
> + int ret;
> +
> + bridge = kzalloc(sizeof(*bridge), GFP_KERNEL);
> + if (!bridge)
> + return -ENOMEM;
> +
> + strscpy(bridge->cio2_node_name, CIO2_HID, sizeof(bridge->cio2_node_name));
> + bridge->cio2_hid_node = (const struct software_node){ bridge->cio2_node_name };

Maybe just

bridge->cio2_hid_node.name = bridge->cio2_node_name;

as the rest is already zeroed by the kzalloc() call ?

> + bridge->cio2 = pci_dev_get(cio2);

As the cio2 pointer is only used to print a message in
cio2_bridge_connect_sensors(), do we need to store it in the bridge
structure, and take a reference to the device ?

> +
> + ret = software_node_register(&bridge->cio2_hid_node);
> + if (ret < 0) {
> + dev_err(dev, "Failed to register the CIO2 HID node\n");
> + goto err_put_cio2;
> + }
> +
> + ret = cio2_bridge_connect_sensors(bridge);
> + if (ret || bridge->n_sensors == 0)
> + goto err_unregister_cio2;
> +
> + dev_info(dev, "Connected %d cameras\n", bridge->n_sensors);
> +
> + fwnode = software_node_fwnode(&bridge->cio2_hid_node);
> + if (!fwnode) {
> + dev_err(dev, "Error getting fwnode from cio2 software_node\n");
> + ret = -ENODEV;
> + goto err_unregister_sensors;

Can this happen ?

> + }
> +
> + set_secondary_fwnode(dev, fwnode);
> +
> + return 0;
> +
> +err_unregister_sensors:
> + cio2_bridge_unregister_sensors(bridge);
> +err_unregister_cio2:
> + software_node_unregister(&bridge->cio2_hid_node);
> +err_put_cio2:
> + pci_dev_put(bridge->cio2);
> +
> + kfree(bridge);
> + return ret;
> +}
> diff --git a/drivers/media/pci/intel/ipu3/cio2-bridge.h b/drivers/media/pci/intel/ipu3/cio2-bridge.h
> new file mode 100644
> index 000000000000..96f5c8a12be0
> --- /dev/null
> +++ b/drivers/media/pci/intel/ipu3/cio2-bridge.h

This file is only included by cio2-bridge.c, so you could inline it
there. Up to you.

> @@ -0,0 +1,108 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/* Author: Dan Scally <djrscally@gmail.com> */
> +#ifndef __CIO2_BRIDGE_H
> +#define __CIO2_BRIDGE_H
> +
> +#include <linux/property.h>
> +
> +#define CIO2_HID "INT343E"
> +#define CIO2_NUM_PORTS 4

There are a few rogue spaces before '4'.

> +
> +#define NODE_SENSOR(_HID, _PROPS) \
> + ((const struct software_node) { \
> + .name = _HID, \
> + .properties = _PROPS, \
> + })
> +
> +#define NODE_PORT(_PORT, _SENSOR_NODE) \
> + ((const struct software_node) { \
> + _PORT, \
> + _SENSOR_NODE, \
> + })
> +
> +#define NODE_ENDPOINT(_EP, _PORT, _PROPS) \
> + ((const struct software_node) { \
> + _EP, \
> + _PORT, \
> + _PROPS, \
> + })
> +
> +enum cio2_sensor_swnodes {
> + SWNODE_SENSOR_HID,
> + SWNODE_SENSOR_PORT,
> + SWNODE_SENSOR_ENDPOINT,
> + SWNODE_CIO2_PORT,
> + SWNODE_CIO2_ENDPOINT,
> + NR_OF_SENSOR_SWNODES
> +};
> +
> +/* Data representation as it is in ACPI SSDB buffer */
> +struct cio2_sensor_ssdb {
> + 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__;
> +
> +struct cio2_property_names {
> + char clock_frequency[16];
> + char rotation[9];
> + char bus_type[9];
> + char data_lanes[11];
> + char remote_endpoint[16];
> +};
> +
> +struct cio2_node_names {
> + char port[6];
> + char endpoint[10];
> + char remote_port[6];
> +};
> +
> +struct cio2_sensor {
> + char name[ACPI_ID_LEN];
> + struct acpi_device *adev;
> +
> + struct software_node swnodes[6];
> + struct cio2_node_names node_names;
> +
> + u32 data_lanes[4];
> + struct cio2_sensor_ssdb ssdb;
> + struct cio2_property_names prop_names;
> + struct property_entry ep_properties[4];
> + struct property_entry dev_properties[3];
> + struct property_entry cio2_properties[3];
> + struct software_node_ref_args local_ref[1];
> + struct software_node_ref_args remote_ref[1];
> +};
> +
> +struct cio2_bridge {
> + struct pci_dev *cio2;
> + char cio2_node_name[ACPI_ID_LEN];
> + struct software_node cio2_hid_node;
> + unsigned int n_sensors;
> + struct cio2_sensor sensors[CIO2_NUM_PORTS];
> +};
> +
> +#endif
> diff --git a/drivers/media/pci/intel/ipu3/ipu3-cio2-main.c b/drivers/media/pci/intel/ipu3/ipu3-cio2-main.c
> index 36e354ecf71e..0d69b593e9f0 100644
> --- a/drivers/media/pci/intel/ipu3/ipu3-cio2-main.c
> +++ b/drivers/media/pci/intel/ipu3/ipu3-cio2-main.c
> @@ -1702,6 +1702,22 @@ static void cio2_queues_exit(struct cio2_device *cio2)
> cio2_queue_exit(cio2, &cio2->queue[i]);
> }
>
> +static bool cio2_check_fwnode_graph(struct fwnode_handle *fwnode)
> +{
> + struct fwnode_handle *endpoint;
> +
> + if (IS_ERR_OR_NULL(fwnode))
> + return false;
> +
> + endpoint = fwnode_graph_get_next_endpoint(fwnode, NULL);
> + if (endpoint) {
> + fwnode_handle_put(endpoint);
> + return true;
> + }
> +
> + return cio2_check_fwnode_graph(fwnode->secondary);

If we have a fwnode->secondary and this check fails there's something
seriously wrong, I wonder if we should print an error message.

Overall this is nice. I think the next version will get my ack :-)

> +}
> +
> /**************** PCI interface ****************/
>
> static int cio2_pci_probe(struct pci_dev *pci_dev,
> @@ -1715,6 +1731,17 @@ static int cio2_pci_probe(struct pci_dev *pci_dev,
> return -ENOMEM;
> cio2->pci_dev = pci_dev;
>
> + /*
> + * 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.
> + */
> + if (!cio2_check_fwnode_graph(dev_fwnode(&pci_dev->dev))) {
> + r = cio2_bridge_init(pci_dev);
> + if (r)
> + return r;
> + }
> +
> r = pcim_enable_device(pci_dev);
> if (r) {
> dev_err(&pci_dev->dev, "failed to enable device (%d)\n", r);
> diff --git a/drivers/media/pci/intel/ipu3/ipu3-cio2.h b/drivers/media/pci/intel/ipu3/ipu3-cio2.h
> index ccf0b85ae36f..520a27c9cdad 100644
> --- a/drivers/media/pci/intel/ipu3/ipu3-cio2.h
> +++ b/drivers/media/pci/intel/ipu3/ipu3-cio2.h
> @@ -437,4 +437,10 @@ static inline struct cio2_queue *vb2q_to_cio2_queue(struct vb2_queue *vq)
> return container_of(vq, struct cio2_queue, vbq);
> }
>
> +#if IS_ENABLED(CONFIG_CIO2_BRIDGE)
> +int cio2_bridge_init(struct pci_dev *cio2);
> +#else
> +int cio2_bridge_init(struct pci_dev *cio2) { return 0; }
> +#endif
> +
> #endif

--
Regards,

Laurent Pinchart