[PATCH v3 0/8] ACPI _CRS CSI-2 and MIPI DisCo for Imaging support

[PATCH v3 0/8] ACPI _CRS CSI-2 and MIPI DisCo for Imaging support

[Sakari Ailus]

Hello all,

Here's an implementation of ACPI 6.4 _CRS CSI-2 resource descriptor and
MIPI DisCo for Imaging 1.0 [1]. What the two basically provide is an
officially sanctioned way to describe CSI-2 connected cameras to operating
system software, something DT based systems have enjoyed for quite some
time already.

The implementation digs the information from ACPI tables (_CRS descriptors
and data + property extensions) and constructs software nodes that are
compatible with Documentation/firmware-guide/acpi/dsd/graph.rst and
Documentation/devicetree/bindings/media/video-interface-devices.yaml . No
specific driver changes are needed.

These patches are on the testing branch of the linux-acpi tree where they
depend on the patch constifying the ACPI pathname argument for
acpi_get_handle() (commit 91fdb91ccca2b48572a1ccf1d382fd599e3e1237).

[1] https://www.mipi.org/specifications/mipi-disco-imaging

since v2:

- Unwrap a few lines.

- Copy CSI-2 resource source string using strscpy() instead of memcpy() in
  scan_check_crs_csi2_instance.

- Fix GRAPH_PORT_NAME() sanity check bug introduced in v2.

- Fix snprintf() return value check for port node name in
  get_mipi_port_handle().

- Fix mipi-img-lane-polarities reading.

- Cast bit value to bool instead of using ... ? 1U : 0U.

- Get primary fwnode using acpi_fwnode_handle().

- Don't use MIPI_IMG_PREFIX in the array of renamed properties.

- Use tabs for indenting drivers/acpi/property.c authors.

- Add a comment on assigning ACPI device's secondary fwnode and assign
  ACPI device's secondary fwnode straight to NULL when unassigning it.

since v1:

- Update copyright notices.

- Include linux/types.h instead of linux/kernel.h in drivers/acpi/mipi.c.

- Use SWNODE_GRAPH_PORT_NAME_FMT instead of plain "port@%u" in
  GRAPH_PORT_NAME macro.

- Make the condition in NEXT_PROPERTY() macro easier to read.

- Unwrap lines to make them moderately longer than 80 characters.

- Use * BITS_PER_TYPE(u8) instead of << 3 to convert bytes to bits in
  init_port_csi2_common().

- Test ACPI framework call success using ACPI_SUCCESS() instead of
  comparing with AE_OK. Likewise for ACPI_FAILURE and != AE_OK.

- Use newly added SOFTWARE_NODE() macro to construct the root software
  node.

- Use str_has_prefix() to test for a string prefix instead of memcmp().

- Add pr_fmt() macro to drivers/acpi/property.c.

- Move logical or operators to the end of the line in
  acpi_properties_prepare().

- Improve bad node type error in acpi_parse_string_ref().

Sakari Ailus (8):
  ACPI: property: Parse data node string references in properties
  ACPI: property: Parse _CRS CSI-2 descriptor
  device property: Add SOFTWARE_NODE() macro for defining software nodes
  ACPI: property: Generate camera swnodes for ACPI and DisCo for Imaging
  ACPI: property: Dig "rotation" property for devices with CSI2 _CRS
  ACPI: property: Rename parsed MIPI DisCo for Imaging properties
  ACPI: property: Skip MIPI property table without "mipi-img" prefix
  ACPI: property: Document _CRS CSI-2 and DisCo for Imaging support

 drivers/acpi/Makefile    |   2 +-
 drivers/acpi/internal.h  |   9 +
 drivers/acpi/mipi.c      | 768 +++++++++++++++++++++++++++++++++++++++
 drivers/acpi/property.c  | 132 +++++--
 drivers/acpi/scan.c      |  35 +-
 include/acpi/acpi_bus.h  |  61 ++++
 include/linux/property.h |   7 +
 7 files changed, 983 insertions(+), 31 deletions(-)
 create mode 100644 drivers/acpi/mipi.c

-- 
2.30.2

[PATCH v3 1/8] ACPI: property: Parse data node string references in properties

[Sakari Ailus]

Add support for parsing property references using strings, besides
reference objects that were previously supported. This allows also
referencing data nodes which was not possible with reference objects.

Also add pr_fmt() macro to prefix printouts.

While at it, update copyright.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
---
 drivers/acpi/property.c | 110 ++++++++++++++++++++++++++++++++++------
 1 file changed, 94 insertions(+), 16 deletions(-)

diff --git a/drivers/acpi/property.c b/drivers/acpi/property.c
index b8d9eb9a433ed..2b69b25c405c5 100644
--- a/drivers/acpi/property.c
+++ b/drivers/acpi/property.c
@@ -2,14 +2,17 @@
 /*
  * ACPI device specific properties support.
  *
- * Copyright (C) 2014, Intel Corporation
+ * Copyright (C) 2014--2023, Intel Corporation
  * All rights reserved.
  *
  * Authors: Mika Westerberg <mika.westerberg@linux.intel.com>
- *          Darren Hart <dvhart@linux.intel.com>
- *          Rafael J. Wysocki <rafael.j.wysocki@intel.com>
+ *	    Darren Hart <dvhart@linux.intel.com>
+ *	    Rafael J. Wysocki <rafael.j.wysocki@intel.com>
+ *	    Sakari Ailus <sakari.ailus@linux.intel.com>
  */
 
+#define pr_fmt(fmt) "ACPI: " fmt
+
 #include <linux/acpi.h>
 #include <linux/device.h>
 #include <linux/export.h>
@@ -795,7 +798,8 @@ acpi_fwnode_get_named_child_node(const struct fwnode_handle *fwnode,
 static int acpi_get_ref_args(struct fwnode_reference_args *args,
 			     struct fwnode_handle *ref_fwnode,
 			     const union acpi_object **element,
-			     const union acpi_object *end, size_t num_args)
+			     const union acpi_object *end, size_t num_args,
+			     bool subnode_string)
 {
 	u32 nargs = 0, i;
 
@@ -803,13 +807,16 @@ static int acpi_get_ref_args(struct fwnode_reference_args *args,
 	 * Find the referred data extension node under the
 	 * referred device node.
 	 */
-	for (; *element < end && (*element)->type == ACPI_TYPE_STRING;
-	     (*element)++) {
-		const char *child_name = (*element)->string.pointer;
-
-		ref_fwnode = acpi_fwnode_get_named_child_node(ref_fwnode, child_name);
-		if (!ref_fwnode)
-			return -EINVAL;
+	if (subnode_string) {
+		for (; *element < end && (*element)->type == ACPI_TYPE_STRING;
+		     (*element)++) {
+			const char *child_name = (*element)->string.pointer;
+
+			ref_fwnode = acpi_fwnode_get_named_child_node(ref_fwnode,
+								      child_name);
+			if (!ref_fwnode)
+				return -EINVAL;
+		}
 	}
 
 	/*
@@ -820,7 +827,8 @@ static int acpi_get_ref_args(struct fwnode_reference_args *args,
 	for (i = 0; (*element) + i < end && i < num_args; i++) {
 		acpi_object_type type = (*element)[i].type;
 
-		if (type == ACPI_TYPE_LOCAL_REFERENCE)
+		if (type == ACPI_TYPE_LOCAL_REFERENCE ||
+		    (!subnode_string && type == ACPI_TYPE_STRING))
 			break;
 
 		if (type == ACPI_TYPE_INTEGER)
@@ -844,6 +852,43 @@ static int acpi_get_ref_args(struct fwnode_reference_args *args,
 	return 0;
 }
 
+static struct fwnode_handle *
+acpi_parse_string_ref(const struct fwnode_handle *fwnode, const char *refstring)
+{
+	acpi_handle scope, handle;
+	struct acpi_data_node *dn;
+	struct acpi_device *device;
+	acpi_status status;
+
+	if (is_acpi_device_node(fwnode)) {
+		scope = to_acpi_device_node(fwnode)->handle;
+	} else if (is_acpi_data_node(fwnode)) {
+		scope = to_acpi_data_node(fwnode)->handle;
+	} else {
+		pr_err("bad node type for node %pfw\n", fwnode);
+		return ERR_PTR(-EINVAL);
+	}
+
+	status = acpi_get_handle(scope, refstring, &handle);
+	if (ACPI_FAILURE(status)) {
+		acpi_handle_debug(scope, "can't get handle for %s", refstring);
+		return ERR_PTR(-EINVAL);
+	}
+
+	device = acpi_fetch_acpi_dev(handle);
+	if (device)
+		return acpi_fwnode_handle(device);
+
+	status = acpi_get_data_full(handle, acpi_nondev_subnode_tag,
+				    (void **)&dn, NULL);
+	if (ACPI_FAILURE(status) || !dn) {
+		acpi_handle_debug(handle, "can't find subnode");
+		return ERR_PTR(-EINVAL);
+	}
+
+	return &dn->fwnode;
+}
+
 /**
  * __acpi_node_get_property_reference - returns handle to the referenced object
  * @fwnode: Firmware node to get the property from
@@ -886,6 +931,7 @@ int __acpi_node_get_property_reference(const struct fwnode_handle *fwnode,
 	const union acpi_object *element, *end;
 	const union acpi_object *obj;
 	const struct acpi_device_data *data;
+	struct fwnode_handle *ref_fwnode;
 	struct acpi_device *device;
 	int ret, idx = 0;
 
@@ -909,16 +955,29 @@ int __acpi_node_get_property_reference(const struct fwnode_handle *fwnode,
 
 		args->fwnode = acpi_fwnode_handle(device);
 		args->nargs = 0;
+		return 0;
+	case ACPI_TYPE_STRING:
+		if (index)
+			return -ENOENT;
+
+		ref_fwnode = acpi_parse_string_ref(fwnode, obj->string.pointer);
+		if (IS_ERR(ref_fwnode))
+			return PTR_ERR(ref_fwnode);
+
+		args->fwnode = ref_fwnode;
+		args->nargs = 0;
+
 		return 0;
 	case ACPI_TYPE_PACKAGE:
 		/*
 		 * If it is not a single reference, then it is a package of
-		 * references followed by number of ints as follows:
+		 * references, followed by number of ints as follows:
 		 *
 		 *  Package () { REF, INT, REF, INT, INT }
 		 *
-		 * The index argument is then used to determine which reference
-		 * the caller wants (along with the arguments).
+		 * Here, REF may be either a local reference or a string. The
+		 * index argument is then used to determine which reference the
+		 * caller wants (along with the arguments).
 		 */
 		break;
 	default:
@@ -942,7 +1001,26 @@ int __acpi_node_get_property_reference(const struct fwnode_handle *fwnode,
 
 			ret = acpi_get_ref_args(idx == index ? args : NULL,
 						acpi_fwnode_handle(device),
-						&element, end, num_args);
+						&element, end, num_args, true);
+			if (ret < 0)
+				return ret;
+
+			if (idx == index)
+				return 0;
+
+			break;
+		case ACPI_TYPE_STRING:
+			ref_fwnode =
+				acpi_parse_string_ref(fwnode,
+						      element->string.pointer);
+			if (IS_ERR(ref_fwnode))
+				return PTR_ERR(ref_fwnode);
+
+			element++;
+
+			ret = acpi_get_ref_args(idx == index ? args : NULL,
+						ref_fwnode, &element, end,
+						num_args, false);
 			if (ret < 0)
 				return ret;
 
-- 
2.30.2

[PATCH v3 2/8] ACPI: property: Parse _CRS CSI-2 descriptor

[Sakari Ailus]

Parse newly added ACPI _CRS CSI-2 descriptor for CSI-2 and camera
configuration. For now, only figure out where the descriptor is present in
order to allow adding information from it to related devices.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
---
 drivers/acpi/Makefile   |   2 +-
 drivers/acpi/internal.h |   7 +
 drivers/acpi/mipi.c     | 320 ++++++++++++++++++++++++++++++++++++++++
 drivers/acpi/scan.c     |  16 +-
 include/acpi/acpi_bus.h |  11 ++
 5 files changed, 351 insertions(+), 5 deletions(-)
 create mode 100644 drivers/acpi/mipi.c

diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
index a5b649e71ab1b..a98fa1bc15548 100644
--- a/drivers/acpi/Makefile
+++ b/drivers/acpi/Makefile
@@ -37,7 +37,7 @@ acpi-$(CONFIG_ACPI_SLEEP)	+= proc.o
 # ACPI Bus and Device Drivers
 #
 acpi-y				+= bus.o glue.o
-acpi-y				+= scan.o
+acpi-y				+= scan.o mipi.o
 acpi-y				+= resource.o
 acpi-y				+= acpi_processor.o
 acpi-y				+= processor_core.o
diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
index ec584442fb298..1ec4aa92bf17a 100644
--- a/drivers/acpi/internal.h
+++ b/drivers/acpi/internal.h
@@ -282,4 +282,11 @@ void acpi_init_lpit(void);
 static inline void acpi_init_lpit(void) { }
 #endif
 
+/*--------------------------------------------------------------------------
+				ACPI and MIPI DisCo for Imaging conversion
+  -------------------------------------------------------------------------- */
+
+void acpi_crs_csi2_swnodes_del_free(void);
+void acpi_bus_scan_crs_csi2(acpi_handle handle);
+
 #endif /* _ACPI_INTERNAL_H_ */
diff --git a/drivers/acpi/mipi.c b/drivers/acpi/mipi.c
new file mode 100644
index 0000000000000..269a6965d56e6
--- /dev/null
+++ b/drivers/acpi/mipi.c
@@ -0,0 +1,320 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * MIPI DisCo for Imaging support.
+ *
+ * Copyright (C) 2023 Intel Corporation
+ */
+
+#include <linux/acpi.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/overflow.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/sort.h>
+#include <linux/string.h>
+
+#include "internal.h"
+
+struct crs_csi2_swnodes {
+	struct list_head list;
+	acpi_handle handle;
+	struct acpi_device_software_nodes *ads;
+};
+
+static LIST_HEAD(crs_csi2_swnodes);
+
+static void crs_csi2_swnode_del_free(struct crs_csi2_swnodes *swnodes)
+{
+	list_del(&swnodes->list);
+	kfree(swnodes);
+}
+
+void acpi_crs_csi2_swnodes_del_free(void)
+{
+	struct crs_csi2_swnodes *swnodes, *swnodes_tmp;
+
+	list_for_each_entry_safe(swnodes, swnodes_tmp, &crs_csi2_swnodes, list)
+		crs_csi2_swnode_del_free(swnodes);
+}
+
+struct crs_csi2_instance {
+	struct list_head list;
+	struct acpi_resource_csi2_serialbus csi2;
+	acpi_handle remote_handle;
+	char remote_name[];
+};
+
+struct crs_csi2 {
+	struct list_head list;
+	acpi_handle handle;
+	struct list_head buses;
+};
+
+struct scan_check_crs_csi2_context {
+	struct list_head res_list;
+	acpi_handle handle;
+};
+
+static acpi_status scan_check_crs_csi2_instance(struct acpi_resource *res,
+						void *context)
+{
+	struct scan_check_crs_csi2_context *inst_context = context;
+	struct acpi_resource_csi2_serialbus *csi2;
+	struct crs_csi2_instance *inst;
+	acpi_handle remote_handle;
+	acpi_status status;
+
+	if (res->type != ACPI_RESOURCE_TYPE_SERIAL_BUS)
+		return AE_OK;
+
+	csi2 = &res->data.csi2_serial_bus;
+
+	if (csi2->type != ACPI_RESOURCE_SERIAL_TYPE_CSI2)
+		return AE_OK;
+
+	if (!csi2->resource_source.string_length) {
+		acpi_handle_debug(inst_context->handle,
+				  "invalid resource source string length\n");
+		return AE_OK;
+	}
+
+	status = acpi_get_handle(NULL, csi2->resource_source.string_ptr,
+				 &remote_handle);
+	if (status != AE_OK) {
+		acpi_handle_warn(inst_context->handle,
+				 "cannot get handle for %s\n",
+				 csi2->resource_source.string_ptr);
+		return AE_OK;
+	}
+
+	inst = kmalloc(struct_size(inst, remote_name,
+				   csi2->resource_source.string_length),
+		       GFP_KERNEL);
+	if (!inst)
+		return AE_OK;
+
+	inst->csi2 = *csi2;
+	strscpy(inst->remote_name, csi2->resource_source.string_ptr,
+		csi2->resource_source.string_length);
+	inst->csi2.resource_source.string_ptr = inst->remote_name;
+	inst->remote_handle = remote_handle;
+
+	list_add(&inst->list, &inst_context->res_list);
+
+	return AE_OK;
+}
+
+static acpi_status scan_check_crs_csi2(acpi_handle handle, u32 nesting_level,
+				       void *context, void **ret)
+{
+	struct scan_check_crs_csi2_context inst_context = {
+		.handle = handle,
+		.res_list = LIST_HEAD_INIT(inst_context.res_list),
+	};
+	struct list_head *list = context;
+	struct crs_csi2 *csi2;
+
+	INIT_LIST_HEAD(&inst_context.res_list);
+
+	acpi_walk_resources(handle, METHOD_NAME__CRS,
+			    scan_check_crs_csi2_instance, &inst_context);
+
+	if (list_empty(&inst_context.res_list))
+		return AE_OK;
+
+	csi2 = kmalloc(sizeof(*csi2), GFP_KERNEL);
+	if (!csi2)
+		return AE_OK;
+
+	csi2->handle = handle;
+	list_replace(&inst_context.res_list, &csi2->buses);
+	list_add(&csi2->list, list);
+
+	return AE_OK;
+}
+
+struct acpi_handle_ref {
+	acpi_handle handle;
+	unsigned int count;
+};
+
+#define NO_CSI2_PORT (~1U)
+
+static int crs_handle_cmp(const void *__a, const void *__b)
+{
+	const struct acpi_handle_ref *a = __a, *b = __b;
+
+	return a->handle < b->handle ? -1 : a->handle > b->handle;
+}
+
+static void crs_csi2_release(struct list_head *crs_csi2_handles)
+{
+	struct crs_csi2 *csi2, *csi2_tmp;
+
+	list_for_each_entry_safe(csi2, csi2_tmp, crs_csi2_handles, list) {
+		struct crs_csi2_instance *inst, *inst_tmp;
+
+		list_for_each_entry_safe(inst, inst_tmp, &csi2->buses, list) {
+			list_del(&inst->list);
+			kfree(inst);
+		}
+
+		list_del(&csi2->list);
+		kfree(csi2);
+	}
+}
+
+/**
+ * acpi_bus_scan_crs_csi2 - Scan a device and its child devices for _CRS CSI-2
+ *
+ * @handle: ACPI handle to scan
+ *
+ * This function does a number of things:
+ *
+ * 1. Scan an ACPI device and its children for _CRS CSI-2 instances. The
+ *    instances are stored for later use.
+ *
+ * 2. Count how many references to other devices _CRS CSI-2 instances have in
+ *    total.
+ *
+ * 3. Count the number of references to other devices for each _CRS CSI-2
+ *    instance.
+ *
+ * 4. Allocate memory for swnodes each ACPI device requires later on, and
+ *    generate a list of such allocations.
+ *
+ * Note that struct acpi_device isn't available yet at this time.
+ *
+ * acpi_scan_lock in scan.c must be held when calling this function.
+ */
+void acpi_bus_scan_crs_csi2(acpi_handle handle)
+{
+	struct acpi_handle_ref *handle_refs;
+	struct acpi_handle_ref *this = NULL;
+	LIST_HEAD(crs_csi2_handles);
+	unsigned int handle_count = 0, this_count;
+	unsigned int curr = 0;
+	struct crs_csi2 *csi2;
+
+	/* Collect the devices that have a _CRS CSI-2 resource */
+	acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, ACPI_UINT32_MAX,
+			    scan_check_crs_csi2, NULL, &crs_csi2_handles, NULL);
+
+	/*
+	 * Figure out how much temporary storage we need for counting
+	 * connections in each device.
+	 */
+	list_for_each_entry(csi2, &crs_csi2_handles, list) {
+		struct crs_csi2_instance *inst;
+
+		handle_count++;
+
+		list_for_each_entry(inst, &csi2->buses, list)
+			handle_count++;
+	}
+
+	/* No handles? Bail out here. */
+	if (!handle_count)
+		return;
+
+	handle_refs = kcalloc(handle_count + 1, sizeof(*handle_refs),
+			      GFP_KERNEL);
+	if (!handle_refs) {
+		acpi_handle_debug(handle, "no memory for %u handle refs\n",
+				  handle_count + 1);
+		return;
+	}
+
+	/* Associate handles to the number of references. */
+	list_for_each_entry(csi2, &crs_csi2_handles, list) {
+		struct crs_csi2_instance *inst;
+		struct acpi_handle_ref *handle_ref;
+
+		handle_ref = &handle_refs[curr++];
+		handle_ref->handle = csi2->handle;
+
+		list_for_each_entry(inst, &csi2->buses, list) {
+			handle_refs[curr].handle = inst->remote_handle;
+			handle_refs[curr].count = 1;
+			handle_ref->count++;
+			curr++;
+		}
+	}
+
+	handle_refs[curr].handle = NULL;
+
+	sort(handle_refs, handle_count, sizeof(*handle_refs), crs_handle_cmp,
+	     NULL);
+
+	/*
+	 * Finally count references in each handle, allocate space for device
+	 * specific ports, properties and fill the _CRS CSI2 descriptor
+	 * originated data.
+	 */
+	this = handle_refs;
+	this_count = this->count;
+	for (curr = 1; curr < handle_count + 1; curr++) {
+		struct acpi_device_software_nodes *ads;
+		struct crs_csi2_swnodes *swnodes;
+		size_t alloc_size;
+		void *end;
+
+		if (this->handle == handle_refs[curr].handle) {
+			this_count += handle_refs[curr].count;
+			continue;
+		}
+
+		/*
+		 * Allocate memory for ports, node pointers (number of nodes +
+		 * 1 (guardian), nodes (root + number of ports * 2 (for for
+		 * every port there is an endpoint)).
+		 */
+		if (check_mul_overflow(sizeof(*ads->ports) +
+				       sizeof(*ads->nodes) * 2 +
+				       sizeof(*ads->nodeptrs) * 2,
+				       (size_t)this_count, &alloc_size) ||
+		    check_add_overflow(sizeof(*ads) + sizeof(*ads->nodes) +
+				       sizeof(*ads->nodeptrs) * 2,
+				       alloc_size, &alloc_size)) {
+			acpi_handle_warn(handle, "too many handles (%u)",
+					 this_count);
+			continue;
+		}
+
+		swnodes = kzalloc(sizeof(*swnodes), GFP_KERNEL);
+		ads = kzalloc(alloc_size, GFP_KERNEL);
+		ads->ports = (void *)(ads + 1);
+		ads->nodes = (void *)(ads->ports + this_count);
+		ads->nodeptrs = (void *)(ads->nodes +
+					 this_count * 2 + 1);
+		end = ads->nodeptrs + this_count * 2 + 2;
+		if (!swnodes || !ads ||
+		    WARN_ON((void *)ads + alloc_size != end)) {
+			kfree(swnodes);
+			kfree(ads);
+			acpi_handle_debug(handle,
+					  "cannot allocate for %u swnodes\n",
+					  this_count);
+		} else {
+			unsigned int i;
+
+			ads->num_ports = this_count;
+			for (i = 0; i < this_count * 2 + 1; i++)
+				ads->nodeptrs[i] = &ads->nodes[i];
+			ads->nodeptrs[i] = NULL;
+			for (i = 0; i < this_count; i++)
+				ads->ports[i].port_nr = NO_CSI2_PORT;
+			swnodes->handle = this->handle;
+			swnodes->ads = ads;
+			list_add(&swnodes->list, &crs_csi2_swnodes);
+		}
+
+		this = &handle_refs[curr];
+		this_count = this->count;
+	}
+
+	kfree(handle_refs);
+
+	crs_csi2_release(&crs_csi2_handles);
+}
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 0c6f06abe3f47..50de874b8f208 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -2423,9 +2423,12 @@ EXPORT_SYMBOL_GPL(acpi_dev_get_next_consumer_dev);
 int acpi_bus_scan(acpi_handle handle)
 {
 	struct acpi_device *device = NULL;
+	int ret = 0;
 
 	acpi_bus_scan_second_pass = false;
 
+	acpi_bus_scan_crs_csi2(handle);
+
 	/* Pass 1: Avoid enumerating devices with missing dependencies. */
 
 	if (ACPI_SUCCESS(acpi_bus_check_add(handle, true, &device)))
@@ -2433,13 +2436,15 @@ int acpi_bus_scan(acpi_handle handle)
 				    acpi_bus_check_add_1, NULL, NULL,
 				    (void **)&device);
 
-	if (!device)
-		return -ENODEV;
+	if (!device) {
+		ret = -ENODEV;
+		goto out_release;
+	}
 
 	acpi_bus_attach(device, (void *)true);
 
 	if (!acpi_bus_scan_second_pass)
-		return 0;
+		goto out_release;
 
 	/* Pass 2: Enumerate all of the remaining devices. */
 
@@ -2452,7 +2457,10 @@ int acpi_bus_scan(acpi_handle handle)
 
 	acpi_bus_attach(device, NULL);
 
-	return 0;
+out_release:
+	acpi_crs_csi2_swnodes_del_free();
+
+	return ret;
 }
 EXPORT_SYMBOL(acpi_bus_scan);
 
diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index e44be31115a67..a05fe22c1175c 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -360,6 +360,17 @@ struct acpi_device_data {
 
 struct acpi_gpio_mapping;
 
+struct acpi_device_software_node_port {
+	unsigned int port_nr;
+};
+
+struct acpi_device_software_nodes {
+	struct acpi_device_software_node_port *ports;
+	struct software_node *nodes;
+	const struct software_node **nodeptrs;
+	unsigned int num_ports;
+};
+
 /* Device */
 struct acpi_device {
 	u32 pld_crc;
-- 
2.30.2

[PATCH v3 3/8] device property: Add SOFTWARE_NODE() macro for defining software nodes

[Sakari Ailus]

Add SOFTWARE_NODE() macro in order to make defining software nodes look
nicer. This is analogous to different PROPERTY_ENTRY_*() macros for
defining properties.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
---
 include/linux/property.h | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/include/linux/property.h b/include/linux/property.h
index 37179e3abad5c..6745a86bc9b97 100644
--- a/include/linux/property.h
+++ b/include/linux/property.h
@@ -477,6 +477,13 @@ struct software_node {
 	const struct property_entry *properties;
 };
 
+#define SOFTWARE_NODE(_name_, _properties_, _parent_)	\
+	(struct software_node) {			\
+		.name = _name_,				\
+		.properties = _properties_,		\
+		.parent = _parent_,			\
+	}
+
 bool is_software_node(const struct fwnode_handle *fwnode);
 const struct software_node *
 to_software_node(const struct fwnode_handle *fwnode);
-- 
2.30.2

[PATCH v3 4/8] ACPI: property: Generate camera swnodes for ACPI and DisCo for Imaging

[Sakari Ailus]

Generate software nodes for information parsed from ACPI _CRS for CSI-2 as
well as MIPI DisCo for Imaging spec. The software nodes are compliant with
existing ACPI or DT definitions and are parsed by relevant drivers without
changes.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
---
 drivers/acpi/internal.h |   1 +
 drivers/acpi/mipi.c     | 353 ++++++++++++++++++++++++++++++++++++++++
 drivers/acpi/scan.c     |  19 +++
 include/acpi/acpi_bus.h |  49 ++++++
 4 files changed, 422 insertions(+)

diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
index 1ec4aa92bf17a..fac87404e294c 100644
--- a/drivers/acpi/internal.h
+++ b/drivers/acpi/internal.h
@@ -288,5 +288,6 @@ static inline void acpi_init_lpit(void) { }
 
 void acpi_crs_csi2_swnodes_del_free(void);
 void acpi_bus_scan_crs_csi2(acpi_handle handle);
+void acpi_init_swnodes(struct acpi_device *device);
 
 #endif /* _ACPI_INTERNAL_H_ */
diff --git a/drivers/acpi/mipi.c b/drivers/acpi/mipi.c
index 269a6965d56e6..5dbdf33a13831 100644
--- a/drivers/acpi/mipi.c
+++ b/drivers/acpi/mipi.c
@@ -14,6 +14,8 @@
 #include <linux/sort.h>
 #include <linux/string.h>
 
+#include <media/v4l2-fwnode.h>
+
 #include "internal.h"
 
 struct crs_csi2_swnodes {
@@ -24,6 +26,17 @@ struct crs_csi2_swnodes {
 
 static LIST_HEAD(crs_csi2_swnodes);
 
+static struct acpi_device_software_nodes *crs_csi2_swnode_get(acpi_handle handle)
+{
+	struct crs_csi2_swnodes *swnodes;
+
+	list_for_each_entry(swnodes, &crs_csi2_swnodes, list)
+		if (swnodes->handle == handle)
+			return swnodes->ads;
+
+	return NULL;
+}
+
 static void crs_csi2_swnode_del_free(struct crs_csi2_swnodes *swnodes)
 {
 	list_del(&swnodes->list);
@@ -141,6 +154,32 @@ struct acpi_handle_ref {
 
 #define NO_CSI2_PORT (~1U)
 
+static unsigned int next_csi2_port_index(struct acpi_device_software_nodes *ads,
+					 unsigned int port_nr)
+{
+	unsigned int i;
+
+	for (i = 0; i < ads->num_ports; i++) {
+		struct acpi_device_software_node_port *port = &ads->ports[i];
+
+		if (port->port_nr == port_nr)
+			return i;
+
+		if (port->port_nr != NO_CSI2_PORT)
+			continue;
+
+		port->port_nr = port_nr;
+
+		return i;
+	}
+
+	return NO_CSI2_PORT;
+}
+
+#define GRAPH_PORT_NAME(var, num)					    \
+	(snprintf((var), sizeof(var), SWNODE_GRAPH_PORT_NAME_FMT, (num)) >= \
+	 sizeof(var))
+
 static int crs_handle_cmp(const void *__a, const void *__b)
 {
 	const struct acpi_handle_ref *a = __a, *b = __b;
@@ -165,6 +204,9 @@ static void crs_csi2_release(struct list_head *crs_csi2_handles)
 	}
 }
 
+#define ACPI_CRS_CSI2_PHY_TYPE_C	0
+#define ACPI_CRS_CSI2_PHY_TYPE_D	1
+
 /**
  * acpi_bus_scan_crs_csi2 - Scan a device and its child devices for _CRS CSI-2
  *
@@ -184,6 +226,8 @@ static void crs_csi2_release(struct list_head *crs_csi2_handles)
  * 4. Allocate memory for swnodes each ACPI device requires later on, and
  *    generate a list of such allocations.
  *
+ * 5. Set up properties for software nodes.
+ *
  * Note that struct acpi_device isn't available yet at this time.
  *
  * acpi_scan_lock in scan.c must be held when calling this function.
@@ -314,7 +358,316 @@ void acpi_bus_scan_crs_csi2(acpi_handle handle)
 		this_count = this->count;
 	}
 
+	/*
+	 * Allocate and set up necessary software nodes for each device and set
+	 * up properties from _CRS CSI2 descriptor.
+	 */
+	list_for_each_entry(csi2, &crs_csi2_handles, list) {
+		struct acpi_device_software_nodes *local_swnodes;
+		struct crs_csi2_instance *inst;
+
+		local_swnodes = crs_csi2_swnode_get(csi2->handle);
+		if (WARN_ON_ONCE(!local_swnodes))
+			continue;
+
+		list_for_each_entry(inst, &csi2->buses, list) {
+			struct acpi_device_software_nodes *remote_swnodes;
+			struct acpi_device_software_node_port *local_port;
+			struct acpi_device_software_node_port *remote_port;
+			struct software_node *local_node, *remote_node;
+			unsigned int local_index, remote_index;
+			unsigned int bus_type;
+
+			remote_swnodes = crs_csi2_swnode_get(inst->remote_handle);
+			if (WARN_ON_ONCE(!remote_swnodes))
+				continue;
+
+			local_index = next_csi2_port_index(local_swnodes, inst->csi2.local_port_instance);
+			remote_index = next_csi2_port_index(remote_swnodes, inst->csi2.resource_source.index);
+
+			if (WARN_ON_ONCE(local_index >= local_swnodes->num_ports) ||
+			    WARN_ON_ONCE(remote_index >= remote_swnodes->num_ports))
+				goto out_free;
+
+			switch (inst->csi2.phy_type) {
+			case ACPI_CRS_CSI2_PHY_TYPE_C:
+				bus_type = V4L2_FWNODE_BUS_TYPE_CSI2_CPHY;
+				break;
+			case ACPI_CRS_CSI2_PHY_TYPE_D:
+				bus_type = V4L2_FWNODE_BUS_TYPE_CSI2_DPHY;
+				break;
+			default:
+				acpi_handle_info(handle,
+						 "ignoring CSI-2 PHY type %u\n",
+						 inst->csi2.phy_type);
+				continue;
+			}
+
+			local_port = &local_swnodes->ports[local_index];
+			local_node = &local_swnodes->nodes[ACPI_DEVICE_SWNODE_EP(local_index)];
+			local_port->remote_ep_ref[0] = SOFTWARE_NODE_REFERENCE(local_node);
+			local_port->crs_csi2_local = true;
+
+			remote_port = &remote_swnodes->ports[remote_index];
+			remote_node = &remote_swnodes->nodes[ACPI_DEVICE_SWNODE_EP(remote_index)];
+			remote_port->remote_ep_ref[0] = SOFTWARE_NODE_REFERENCE(remote_node);
+
+			local_port->ep_props[ACPI_DEVICE_SWNODE_EP_REMOTE_EP] =
+				PROPERTY_ENTRY_REF_ARRAY("remote-endpoint",
+							 remote_port->remote_ep_ref);
+			local_port->ep_props[ACPI_DEVICE_SWNODE_EP_BUS_TYPE] =
+				PROPERTY_ENTRY_U32("bus-type", bus_type);
+			local_port->ep_props[ACPI_DEVICE_SWNODE_EP_REG] =
+				PROPERTY_ENTRY_U32("reg", 0);
+			local_port->port_props[ACPI_DEVICE_SWNODE_PRT_REG] =
+				PROPERTY_ENTRY_U32("reg", inst->csi2.local_port_instance);
+			if (GRAPH_PORT_NAME(local_port->port_name,
+					    inst->csi2.local_port_instance))
+				acpi_handle_warn(handle,
+						 "name for local port %u too long",
+						 inst->csi2.local_port_instance);
+
+			remote_port->ep_props[ACPI_DEVICE_SWNODE_EP_REMOTE_EP] =
+				PROPERTY_ENTRY_REF_ARRAY("remote-endpoint", local_port->remote_ep_ref);
+			remote_port->ep_props[ACPI_DEVICE_SWNODE_EP_BUS_TYPE] =
+				PROPERTY_ENTRY_U32("bus-type", bus_type);
+			remote_port->ep_props[ACPI_DEVICE_SWNODE_EP_REG] =
+				PROPERTY_ENTRY_U32("reg", 0);
+			remote_port->port_props[ACPI_DEVICE_SWNODE_PRT_REG] =
+				PROPERTY_ENTRY_U32("reg",
+						   inst->csi2.resource_source.index);
+			if (GRAPH_PORT_NAME(remote_port->port_name,
+					    inst->csi2.resource_source.index))
+				acpi_handle_warn(handle,
+						 "name for remote port %u too long",
+						 inst->csi2.resource_source.index);
+		}
+	}
+
+out_free:
 	kfree(handle_refs);
 
 	crs_csi2_release(&crs_csi2_handles);
 }
+
+/*
+ * Get the index of the next property in the property array, with a given
+ * maximum values.
+ */
+#define NEXT_PROPERTY(index, max)				\
+	(WARN_ON(++(index) >= ACPI_DEVICE_SWNODE_##max) ?	\
+	 ACPI_DEVICE_SWNODE_##max : (index) - 1)
+
+static struct fwnode_handle *get_mipi_port_handle(struct acpi_device *device,
+						  unsigned int port)
+{
+	static const char mipi_port_prefix[] = "mipi-img-port-";
+	char mipi_port_name[sizeof(mipi_port_prefix) + 2];
+
+	if (snprintf(mipi_port_name, sizeof(mipi_port_name), "%s%u",
+		     mipi_port_prefix, port) >= sizeof(mipi_port_name)) {
+		acpi_handle_info(acpi_device_handle(device),
+				 "mipi port name too long for port %u\n", port);
+		return NULL;
+	}
+
+	return fwnode_get_named_child_node(acpi_fwnode_handle(device),
+					   mipi_port_name);
+}
+
+static void init_port_csi2_common(struct acpi_device *device,
+				  struct fwnode_handle *mipi_port_fwnode,
+				  unsigned int *ep_prop_index,
+				  unsigned int port_nr)
+{
+	unsigned int port_index = next_csi2_port_index(device->swnodes, port_nr);
+	struct acpi_device_software_nodes *ads = device->swnodes;
+	struct acpi_device_software_node_port *port = &ads->ports[port_index];
+	unsigned int num_lanes = 0;
+	union {
+		u32 val;
+		/* Data lanes + the clock lane */
+		u8 val8[BITS_TO_BYTES(ARRAY_SIZE(port->data_lanes) + 1)];
+	} u;
+	int ret;
+
+	*ep_prop_index = ACPI_DEVICE_SWNODE_EP_CLOCK_LANES;
+
+	if (GRAPH_PORT_NAME(port->port_name, port_nr))
+		return;
+
+	ads->nodes[ACPI_DEVICE_SWNODE_PRT(port_index)] =
+		SOFTWARE_NODE(port->port_name, port->port_props,
+			      &ads->nodes[ACPI_DEVICE_SWNODE_ROOT]);
+
+	ret = fwnode_property_read_u8(mipi_port_fwnode, "mipi-img-clock-lane", u.val8);
+	if (!ret) {
+		port->ep_props[NEXT_PROPERTY(*ep_prop_index, EP_CLOCK_LANES)] =
+			PROPERTY_ENTRY_U32("clock-lanes", *u.val8);
+	}
+	ret = fwnode_property_count_u8(mipi_port_fwnode, "mipi-img-data-lanes");
+	if (ret > 0) {
+		num_lanes = ret;
+
+		if (num_lanes > ARRAY_SIZE(port->data_lanes)) {
+			acpi_handle_warn(acpi_device_handle(device),
+					 "too many data lanes (%u)\n",
+					 num_lanes);
+			num_lanes = ARRAY_SIZE(port->data_lanes);
+		}
+
+		ret = fwnode_property_read_u8_array(mipi_port_fwnode, "mipi-img-data-lanes",
+						    u.val8, num_lanes);
+		if (!ret) {
+			unsigned int i;
+
+			for (i = 0; i < num_lanes; i++)
+				port->data_lanes[i] = u.val8[i];
+
+			port->ep_props[NEXT_PROPERTY(*ep_prop_index, EP_DATA_LANES)] =
+				PROPERTY_ENTRY_U32_ARRAY_LEN("data-lanes", port->data_lanes,
+							     num_lanes);
+		}
+	}
+
+	ret = fwnode_property_count_u8(mipi_port_fwnode, "mipi-img-lane-polarities");
+	if (ret > 0) {
+		unsigned int bytes = min_t(unsigned int, ret, sizeof(u.val8));
+
+		fwnode_property_read_u8_array(mipi_port_fwnode,
+					      "mipi-img-lane-polarities",
+					      u.val8, bytes);
+
+		/* Total number of lanes here is clock lane + data lanes */
+		if (bytes * BITS_PER_TYPE(u8) >= 1 + num_lanes) {
+			unsigned int i;
+
+			/* Move polarity bits to the lane polarity u32 array */
+			for (i = 0; i < 1 + num_lanes; i++)
+				port->lane_polarities[i] =
+					(bool)(u.val8[i >> 3] & (1 << (i & 7)));
+
+			port->ep_props[NEXT_PROPERTY(*ep_prop_index, EP_LANE_POLARITIES)] =
+				PROPERTY_ENTRY_U32_ARRAY_LEN("lane-polarities",
+							     port->lane_polarities,
+							     1 + num_lanes);
+		} else {
+			acpi_handle_warn(acpi_device_handle(device),
+					 "too few lane polarity bytes (%u)\n",
+					 bytes);
+		}
+	}
+
+	ads->nodes[ACPI_DEVICE_SWNODE_EP(port_index)] =
+		SOFTWARE_NODE("endpoint@0", ads->ports[port_index].ep_props,
+			      &ads->nodes[ACPI_DEVICE_SWNODE_PRT(port_index)]);
+}
+
+static void init_port_csi2_local(struct acpi_device *device,
+				 unsigned int port_nr)
+{
+	unsigned int port_index = next_csi2_port_index(device->swnodes, port_nr);
+	struct fwnode_handle *mipi_port_fwnode =
+		get_mipi_port_handle(device, port_nr);
+	struct acpi_device_software_node_port *port =
+		&device->swnodes->ports[port_index];
+	unsigned int ep_prop_index;
+	int ret;
+
+	init_port_csi2_common(device, mipi_port_fwnode, &ep_prop_index, port_nr);
+
+	ret = fwnode_property_count_u64(mipi_port_fwnode, "mipi-img-link-frequencies");
+	if (ret > 0) {
+		unsigned int num_link_freqs = ret;
+
+		if (num_link_freqs > ARRAY_SIZE(port->link_frequencies)) {
+			acpi_handle_info(acpi_device_handle(device),
+					 "too many link frequencies %u\n",
+					 num_link_freqs);
+			num_link_freqs = ARRAY_SIZE(port->link_frequencies);
+		}
+
+		ret = fwnode_property_read_u64_array(mipi_port_fwnode,
+						     "mipi-img-link-frequencies",
+						     port->link_frequencies,
+						     num_link_freqs);
+		if (!ret)
+			port->ep_props[NEXT_PROPERTY(ep_prop_index, EP_LINK_FREQUENCIES)] =
+				PROPERTY_ENTRY_U64_ARRAY_LEN("link-frequencies",
+							     port->link_frequencies,
+							     num_link_freqs);
+		else
+			acpi_handle_info(acpi_device_handle(device),
+					 "can't get link frequencies (%d)\n",
+					 ret);
+	}
+
+	fwnode_handle_put(mipi_port_fwnode);
+}
+
+static void init_port_csi2_remote(struct acpi_device *device,
+				  unsigned int port_nr)
+{
+	struct fwnode_handle *mipi_port_fwnode = get_mipi_port_handle(device, port_nr);
+	unsigned int ep_prop_index;
+
+	init_port_csi2_common(device, mipi_port_fwnode, &ep_prop_index, port_nr);
+
+	fwnode_handle_put(mipi_port_fwnode);
+}
+
+/**
+ * acpi_init_swnodes - Set up software nodes for properties gathered elsewhere
+ *
+ * @device: ACPI device for which the software nodes are initialised
+ *
+ * Initialise and register software nodes for properties for which the data is
+ * gathered elsewhere, e.g. _CRS CSI-2 descriptors. The process itself takes
+ * place before this function is called.
+ *
+ * acpi_scan_lock in scan.c must be held when calling this function.
+ */
+void acpi_init_swnodes(struct acpi_device *device)
+{
+	struct acpi_device_software_nodes *ads;
+	struct acpi_buffer buffer = { .length = ACPI_ALLOCATE_BUFFER };
+	struct fwnode_handle *primary;
+	unsigned int i;
+	int ret;
+
+	device->swnodes = ads = crs_csi2_swnode_get(device->handle);
+	if (!ads)
+		return;
+
+	if (ACPI_FAILURE(acpi_get_name(device->handle, ACPI_FULL_PATHNAME, &buffer))) {
+		acpi_handle_warn(acpi_device_handle(device), "cannot get path name\n");
+		return;
+	}
+
+	ads->nodes[ACPI_DEVICE_SWNODE_ROOT] =
+		SOFTWARE_NODE(buffer.pointer, ads->dev_props, NULL);
+
+	for (i = 0; i < ads->num_ports; i++) {
+		struct acpi_device_software_node_port *port = &ads->ports[i];
+
+		if (port->crs_csi2_local)
+			init_port_csi2_local(device, port->port_nr);
+		else
+			init_port_csi2_remote(device, port->port_nr);
+	}
+
+	ret = software_node_register_node_group(ads->nodeptrs);
+	if (ret < 0) {
+		acpi_handle_warn(acpi_device_handle(device),
+				 "cannot register software nodes (%d)!\n", ret);
+		device->swnodes = NULL;
+		return;
+	}
+
+	/*
+	 * Note we can't use set_secondary_fwnode() here as the device's
+	 * primary fwnode hasn't been set yet.
+	 */
+	primary = acpi_fwnode_handle(device);
+	primary->secondary = software_node_fwnode(ads->nodes);
+}
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 50de874b8f208..9cc30c9c87080 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -449,10 +449,28 @@ static void acpi_free_power_resources_lists(struct acpi_device *device)
 	}
 }
 
+static void acpi_free_swnodes(struct acpi_device *device)
+{
+	struct acpi_device_software_nodes *ads = device->swnodes;
+	struct fwnode_handle *primary;
+
+	if (!ads)
+		return;
+
+	software_node_unregister_node_group(ads->nodeptrs);
+	primary = acpi_fwnode_handle(device);
+	primary->secondary = NULL;
+	kfree(ads->nodes[ACPI_DEVICE_SWNODE_ROOT].name);
+	kfree(ads);
+
+	device->swnodes = NULL;
+}
+
 static void acpi_device_release(struct device *dev)
 {
 	struct acpi_device *acpi_dev = to_acpi_device(dev);
 
+	acpi_free_swnodes(acpi_dev);
 	acpi_free_properties(acpi_dev);
 	acpi_free_pnp_ids(&acpi_dev->pnp);
 	acpi_free_power_resources_lists(acpi_dev);
@@ -1771,6 +1789,7 @@ void acpi_init_device_object(struct acpi_device *device, acpi_handle handle,
 	acpi_device_get_busid(device);
 	acpi_set_pnp_ids(handle, &device->pnp, type);
 	acpi_init_properties(device);
+	acpi_init_swnodes(device);
 	acpi_bus_get_flags(device);
 	device->flags.match_driver = false;
 	device->flags.initialized = true;
diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index a05fe22c1175c..9a7729e96d14c 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -360,8 +360,54 @@ struct acpi_device_data {
 
 struct acpi_gpio_mapping;
 
+enum acpi_device_swnode_dev_props {
+	ACPI_DEVICE_SWNODE_DEV_NUM_OF,
+	ACPI_DEVICE_SWNODE_DEV_NUM_ENTRIES
+};
+
+enum acpi_device_swnode_port_props {
+	ACPI_DEVICE_SWNODE_PRT_REG,
+	ACPI_DEVICE_SWNODE_PRT_NUM_OF,
+	ACPI_DEVICE_SWNODE_PRT_NUM_ENTRIES
+};
+
+enum acpi_device_swnode_ep_props {
+	ACPI_DEVICE_SWNODE_EP_REMOTE_EP,
+	ACPI_DEVICE_SWNODE_EP_BUS_TYPE,
+	ACPI_DEVICE_SWNODE_EP_REG,
+	ACPI_DEVICE_SWNODE_EP_CLOCK_LANES,
+	ACPI_DEVICE_SWNODE_EP_DATA_LANES,
+	ACPI_DEVICE_SWNODE_EP_LANE_POLARITIES,
+	/* TX only */
+	ACPI_DEVICE_SWNODE_EP_LINK_FREQUENCIES,
+	ACPI_DEVICE_SWNODE_EP_NUM_OF,
+	ACPI_DEVICE_SWNODE_EP_NUM_ENTRIES
+};
+
+#define ACPI_DEVICE_SWNODE_ROOT			0
+/*
+ * Each device has a root swnode plus two times as many nodes as the
+ * number of CSI-2 ports.
+ */
+#define ACPI_DEVICE_SWNODE_PRT(port)		(1 + 2 * (port))
+#define ACPI_DEVICE_SWNODE_EP(endpoint)	\
+	(ACPI_DEVICE_SWNODE_PRT(endpoint) + 1)
+
+#define ACPI_DEVICE_SWNODE_CSI2_DATA_LANES		4
+
 struct acpi_device_software_node_port {
+	char port_name[8];
+	u32 data_lanes[ACPI_DEVICE_SWNODE_CSI2_DATA_LANES];
+	u32 lane_polarities[1 /* clock lane */ +
+			    ACPI_DEVICE_SWNODE_CSI2_DATA_LANES];
+	u64 link_frequencies[4];
 	unsigned int port_nr;
+	bool crs_csi2_local;
+
+	struct property_entry port_props[ACPI_DEVICE_SWNODE_PRT_NUM_ENTRIES];
+	struct property_entry ep_props[ACPI_DEVICE_SWNODE_EP_NUM_ENTRIES];
+
+	struct software_node_ref_args remote_ep_ref[1];
 };
 
 struct acpi_device_software_nodes {
@@ -369,6 +415,8 @@ struct acpi_device_software_nodes {
 	struct software_node *nodes;
 	const struct software_node **nodeptrs;
 	unsigned int num_ports;
+
+	struct property_entry dev_props[ACPI_DEVICE_SWNODE_DEV_NUM_ENTRIES];
 };
 
 /* Device */
@@ -377,6 +425,7 @@ struct acpi_device {
 	int device_type;
 	acpi_handle handle;		/* no handle for fixed hardware */
 	struct fwnode_handle fwnode;
+	struct acpi_device_software_nodes *swnodes;
 	struct list_head wakeup_list;
 	struct list_head del_list;
 	struct acpi_device_status status;
-- 
2.30.2

[PATCH v3 5/8] ACPI: property: Dig "rotation" property for devices with CSI2 _CRS

[Sakari Ailus]

Dig "rotation" property value for devices with _CRS CSI2 resource
descriptor. The value comes from _PLD (physical location of device)
object, if it exists for the device.

This way camera sensor drivers that know the "rotation" property do not
need to care about _PLD on ACPI.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
---
 drivers/acpi/mipi.c     | 16 ++++++++++++++++
 include/acpi/acpi_bus.h |  1 +
 2 files changed, 17 insertions(+)

diff --git a/drivers/acpi/mipi.c b/drivers/acpi/mipi.c
index 5dbdf33a13831..b81bfa1edd8ad 100644
--- a/drivers/acpi/mipi.c
+++ b/drivers/acpi/mipi.c
@@ -629,16 +629,32 @@ static void init_port_csi2_remote(struct acpi_device *device,
  */
 void acpi_init_swnodes(struct acpi_device *device)
 {
+	struct fwnode_handle *fwnode = acpi_fwnode_handle(device);
 	struct acpi_device_software_nodes *ads;
 	struct acpi_buffer buffer = { .length = ACPI_ALLOCATE_BUFFER };
 	struct fwnode_handle *primary;
+	struct acpi_pld_info *pld;
+	unsigned int prop_index = 0;
 	unsigned int i;
+	u32 val;
 	int ret;
 
 	device->swnodes = ads = crs_csi2_swnode_get(device->handle);
 	if (!ads)
 		return;
 
+	/*
+	 * Check if "rotation" property exists and if it doesn't but there's a
+	 * _PLD object, then get the rotation value from there.
+	 */
+	if (fwnode_property_read_u32(fwnode, "rotation", &val) &&
+	    ACPI_SUCCESS(acpi_get_physical_device_location(acpi_device_handle(device),
+							   &pld))) {
+		ads->dev_props[NEXT_PROPERTY(prop_index, DEV_ROTATION)] =
+			PROPERTY_ENTRY_U32("rotation", pld->rotation * 45U);
+		kfree(pld);
+	}
+
 	if (ACPI_FAILURE(acpi_get_name(device->handle, ACPI_FULL_PATHNAME, &buffer))) {
 		acpi_handle_warn(acpi_device_handle(device), "cannot get path name\n");
 		return;
diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index 9a7729e96d14c..3c4a1daed33f1 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -361,6 +361,7 @@ struct acpi_device_data {
 struct acpi_gpio_mapping;
 
 enum acpi_device_swnode_dev_props {
+	ACPI_DEVICE_SWNODE_DEV_ROTATION,
 	ACPI_DEVICE_SWNODE_DEV_NUM_OF,
 	ACPI_DEVICE_SWNODE_DEV_NUM_ENTRIES
 };
-- 
2.30.2

[PATCH v3 6/8] ACPI: property: Rename parsed MIPI DisCo for Imaging properties

[Sakari Ailus]

MIPI DisCo for Imaging defines properties for sensor-adjacent devices such
as EEPROM, LED flash or lens VCM as either device or sub-node references.
This is compliant with existing DT definitions apart from property names.

Rename parsed MIPI-defined properties so drivers will have a unified view
of them as defined in DT and already parsed by drivers. This can be done
in-place as the MIPI-defined property strings are always longer than the
DT one. This also results in loss of constness in parser function
arguments.

Individual bindings to devices could define the references differently
between MIPI DisCo for Imaging and DT, in terms of device or sub-node
references. This will still need to be handled in the drivers themselves.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
---
 drivers/acpi/internal.h |  1 +
 drivers/acpi/mipi.c     | 37 +++++++++++++++++++++++++++++++++++++
 drivers/acpi/property.c | 22 ++++++++++++----------
 3 files changed, 50 insertions(+), 10 deletions(-)

diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
index fac87404e294c..f107094bfe16f 100644
--- a/drivers/acpi/internal.h
+++ b/drivers/acpi/internal.h
@@ -289,5 +289,6 @@ static inline void acpi_init_lpit(void) { }
 void acpi_crs_csi2_swnodes_del_free(void);
 void acpi_bus_scan_crs_csi2(acpi_handle handle);
 void acpi_init_swnodes(struct acpi_device *device);
+void acpi_properties_prepare_mipi(union acpi_object *elements);
 
 #endif /* _ACPI_INTERNAL_H_ */
diff --git a/drivers/acpi/mipi.c b/drivers/acpi/mipi.c
index b81bfa1edd8ad..4211b53b41682 100644
--- a/drivers/acpi/mipi.c
+++ b/drivers/acpi/mipi.c
@@ -687,3 +687,40 @@ void acpi_init_swnodes(struct acpi_device *device)
 	primary = acpi_fwnode_handle(device);
 	primary->secondary = software_node_fwnode(ads->nodes);
 }
+
+static const struct mipi_disco_prop {
+	const char *mipi_prop;
+	const char *dt_prop;
+} mipi_disco_props[] = {
+	{ "mipi-img-lens-focus",	"lens-focus" },
+	{ "mipi-img-flash-leds",	"flash-leds" },
+	{ "mipi-img-clock-frequency",	"clock-frequency" },
+	{ "mipi-img-led-max-current",	"led-max-microamp" },
+	{ "mipi-img-flash-max-current",	"flash-max-microamp" },
+	{ "mipi-img-flash-max-timeout",	"flash-max-timeout-us" },
+};
+
+/**
+ * acpi_properties_prepare_mipi - Rename MIPI properties as commin DT ones
+ *
+ * @elements: ACPI object containing _DSD properties for a device node
+ *
+ * Renames MIPI-defined properties as common DT ones. The pre-requisite is that
+ * the names of all such MIPI properties are no longer than the corresponding DT
+ * ones.
+ */
+void acpi_properties_prepare_mipi(union acpi_object *elements)
+{
+	unsigned int i;
+
+	/* Replace MIPI DisCo for Imaging property names with DT equivalents. */
+	for (i = 0; i < ARRAY_SIZE(mipi_disco_props); i++) {
+		if (!strcmp(mipi_disco_props[i].mipi_prop,
+			    elements[0].string.pointer)) {
+			WARN_ON(strscpy(elements[0].string.pointer,
+					mipi_disco_props[i].dt_prop,
+					elements[0].string.length) < 0);
+			break;
+		}
+	}
+}
diff --git a/drivers/acpi/property.c b/drivers/acpi/property.c
index 2b69b25c405c5..0f1dd9cc525bc 100644
--- a/drivers/acpi/property.c
+++ b/drivers/acpi/property.c
@@ -124,7 +124,7 @@ static bool acpi_nondev_subnode_extract(union acpi_object *desc,
 }
 
 static bool acpi_nondev_subnode_data_ok(acpi_handle handle,
-					const union acpi_object *link,
+					union acpi_object *link,
 					struct list_head *list,
 					struct fwnode_handle *parent)
 {
@@ -145,7 +145,7 @@ static bool acpi_nondev_subnode_data_ok(acpi_handle handle,
 }
 
 static bool acpi_nondev_subnode_ok(acpi_handle scope,
-				   const union acpi_object *link,
+				   union acpi_object *link,
 				   struct list_head *list,
 				   struct fwnode_handle *parent)
 {
@@ -276,22 +276,24 @@ static bool acpi_property_value_ok(const union acpi_object *value)
 	return false;
 }
 
-static bool acpi_properties_format_valid(const union acpi_object *properties)
+static bool acpi_properties_prepare(union acpi_object *properties)
 {
-	int i;
+	unsigned int i;
 
 	for (i = 0; i < properties->package.count; i++) {
-		const union acpi_object *property;
+		union acpi_object *property = &properties->package.elements[i];
+		union acpi_object *elements = property->package.elements;
 
-		property = &properties->package.elements[i];
 		/*
 		 * Only two elements allowed, the first one must be a string and
 		 * the second one has to satisfy certain conditions.
 		 */
-		if (property->package.count != 2
-		    || property->package.elements[0].type != ACPI_TYPE_STRING
-		    || !acpi_property_value_ok(&property->package.elements[1]))
+		if (property->package.count != 2 ||
+		    elements[0].type != ACPI_TYPE_STRING ||
+		    !acpi_property_value_ok(&elements[1]))
 			return false;
+
+		acpi_properties_prepare_mipi(elements);
 	}
 	return true;
 }
@@ -523,7 +525,7 @@ static bool acpi_extract_properties(acpi_handle scope, union acpi_object *desc,
 		 * We found the matching GUID. Now validate the format of the
 		 * package immediately following it.
 		 */
-		if (!acpi_properties_format_valid(properties))
+		if (!acpi_properties_prepare(properties))
 			continue;
 
 		acpi_data_add_props(data, (const guid_t *)guid->buffer.pointer,
-- 
2.30.2

[PATCH v3 7/8] ACPI: property: Skip MIPI property table without "mipi-img" prefix

[Sakari Ailus]

For all _DSD properties, skip going through the MIPI DisCo for Imaging
property name substitution table if the property doesn't have "mipi-img-"
prefix.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
---
 drivers/acpi/mipi.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/acpi/mipi.c b/drivers/acpi/mipi.c
index 4211b53b41682..17fcc0417e27d 100644
--- a/drivers/acpi/mipi.c
+++ b/drivers/acpi/mipi.c
@@ -688,6 +688,8 @@ void acpi_init_swnodes(struct acpi_device *device)
 	primary->secondary = software_node_fwnode(ads->nodes);
 }
 
+#define MIPI_IMG_PREFIX "mipi-img-"
+
 static const struct mipi_disco_prop {
 	const char *mipi_prop;
 	const char *dt_prop;
@@ -713,6 +715,9 @@ void acpi_properties_prepare_mipi(union acpi_object *elements)
 {
 	unsigned int i;
 
+	if (!str_has_prefix(elements[0].string.pointer, MIPI_IMG_PREFIX))
+		return;
+
 	/* Replace MIPI DisCo for Imaging property names with DT equivalents. */
 	for (i = 0; i < ARRAY_SIZE(mipi_disco_props); i++) {
 		if (!strcmp(mipi_disco_props[i].mipi_prop,
-- 
2.30.2

[PATCH v3 8/8] ACPI: property: Document _CRS CSI-2 and DisCo for Imaging support

[Sakari Ailus]

Document how ACPI _CRS CSI-2 and DisCo for Imaging works. It's non-trivial
so such documentation can be useful.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
---
 drivers/acpi/mipi.c | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/drivers/acpi/mipi.c b/drivers/acpi/mipi.c
index 17fcc0417e27d..e87cfb584e39a 100644
--- a/drivers/acpi/mipi.c
+++ b/drivers/acpi/mipi.c
@@ -3,6 +3,43 @@
  * MIPI DisCo for Imaging support.
  *
  * Copyright (C) 2023 Intel Corporation
+ *
+ * _CRS CSI-2 descriptors, as defined starting from ACPI 6.4 [1], contain
+ * information on cross-device CSI-2 bus configuration. The descriptors are
+ * located under transmitter devices, and the receiver devices have no direct
+ * way to access them even if the information in these descriptors is equally
+ * important for receivers. This information is amended with MIPI DisCo for
+ * Imaging [2] specification that defines _DSD data nodes and properties.
+ *
+ * The support for these is based on two-fold approach, firstly renaming
+ * properties where semantics matches and secondly gathering information to
+ * generate properties using information gathered from various sources. The
+ * former is trivial (see acpi_properties_prepare_mipi() at the end of the
+ * file) whereas the latter requires a more elaborate explanation.
+ *
+ * acpi_bus_scan_crs_csi2() scans an ACPI bus for devices with _CRS CSI-2
+ * descriptors and stores them to a linked list. This is done as traversing just
+ * this list is much smaller task than the entire DSDT. This list is then used
+ * to figure out how much memory is needed for swnodes related to a given ACPI
+ * device (handle). Further on, the same function sets the property values for
+ * the properties the values of which are obtained from the _CRS CSI-2
+ * descriptor. The information is stored into another list where the information
+ * can be looked up based on device's acpi_handle as the struct acpi_device
+ * isn't available yet at this point (and could not, as cross-device references
+ * need to be set up before the devices are available for drivers to probe).
+ *
+ * For each struct acpi_device, acpi_init_swnodes() further obtains information
+ * required to find out the values for the rest of the properties needed by
+ * drivers. This includes all port and endpoint properties as the node
+ * structures used by DT graphs and DisCo for Imaging are different. Finally the
+ * function registers software nodes for the device and sets the secondary
+ * pointer for the ACPI device's fwnode.
+ *
+ * Access to data the structures is serialised using acpi_scan_lock in scan.c.
+ *
+ * [1] https://uefi.org/sites/default/files/resources/ACPI_Spec_6_4_Jan22.pdf
+ *
+ * [2] https://www.mipi.org/specifications/mipi-disco-imaging
  */
 
 #include <linux/acpi.h>
-- 
2.30.2

Re: [PATCH v3 1/8] ACPI: property: Parse data node string references in properties

[Andy Shevchenko]

On Thu, Jan 26, 2023 at 12:40:54AM +0200, Sakari Ailus wrote:
> Add support for parsing property references using strings, besides
> reference objects that were previously supported. This allows also
> referencing data nodes which was not possible with reference objects.
> 
> Also add pr_fmt() macro to prefix printouts.
> 
> While at it, update copyright.

...

> - * Copyright (C) 2014, Intel Corporation
> + * Copyright (C) 2014--2023, Intel Corporation

As I pointed out this is non-traditional way on how you provide range of the
years in the Copyright line.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v3 2/8] ACPI: property: Parse _CRS CSI-2 descriptor

[Andy Shevchenko]

On Thu, Jan 26, 2023 at 12:40:55AM +0200, Sakari Ailus wrote:
> Parse newly added ACPI _CRS CSI-2 descriptor for CSI-2 and camera
> configuration. For now, only figure out where the descriptor is present in
> order to allow adding information from it to related devices.

...

> +	if (status != AE_OK) {

ACPI_FAILURE()

> +		acpi_handle_warn(inst_context->handle,
> +				 "cannot get handle for %s\n",
> +				 csi2->resource_source.string_ptr);
> +		return AE_OK;
> +	}

...

> +	struct scan_check_crs_csi2_context inst_context = {
> +		.handle = handle,
> +		.res_list = LIST_HEAD_INIT(inst_context.res_list),
> +	};
> +	struct list_head *list = context;
> +	struct crs_csi2 *csi2;

> +	INIT_LIST_HEAD(&inst_context.res_list);

Do you still need this?

...

> +	acpi_walk_resources(handle, METHOD_NAME__CRS,
> +			    scan_check_crs_csi2_instance, &inst_context);
> +
> +	if (list_empty(&inst_context.res_list))
> +		return AE_OK;

I'm wondering if you can utilize acpi_dev_get_resources().

...

> +	/* Collect the devices that have a _CRS CSI-2 resource */
> +	acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, ACPI_UINT32_MAX,

Other serial buses limit the DEPTH by 32, why do we need more here?

> +			    scan_check_crs_csi2, NULL, &crs_csi2_handles, NULL);

...

> +	sort(handle_refs, handle_count, sizeof(*handle_refs), crs_handle_cmp,
> +	     NULL);

A single line?

...

> +		if (check_mul_overflow(sizeof(*ads->ports) +
> +				       sizeof(*ads->nodes) * 2 +
> +				       sizeof(*ads->nodeptrs) * 2,
> +				       (size_t)this_count, &alloc_size) ||

So, now you know why this_count can't be type of size_t?

> +		    check_add_overflow(sizeof(*ads) + sizeof(*ads->nodes) +
> +				       sizeof(*ads->nodeptrs) * 2,
> +				       alloc_size, &alloc_size)) {
> +			acpi_handle_warn(handle, "too many handles (%u)",
> +					 this_count);
> +			continue;
> +		}

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v3 4/8] ACPI: property: Generate camera swnodes for ACPI and DisCo for Imaging

[Andy Shevchenko]

On Thu, Jan 26, 2023 at 12:40:57AM +0200, Sakari Ailus wrote:
> Generate software nodes for information parsed from ACPI _CRS for CSI-2 as
> well as MIPI DisCo for Imaging spec. The software nodes are compliant with
> existing ACPI or DT definitions and are parsed by relevant drivers without
> changes.

...

> +static unsigned int next_csi2_port_index(struct acpi_device_software_nodes *ads,
> +					 unsigned int port_nr)
> +{
> +	unsigned int i;
> +
> +	for (i = 0; i < ads->num_ports; i++) {
> +		struct acpi_device_software_node_port *port = &ads->ports[i];
> +
> +		if (port->port_nr == port_nr)
> +			return i;

> +		if (port->port_nr != NO_CSI2_PORT)
> +			continue;
> +
> +		port->port_nr = port_nr;
> +
> +		return i;

Maybe it would be better to use the same pattern as above?

		if (port->port_nr == NO_CSI2_PORT) {
			port->port_nr = port_nr;
			return i;
		}

> +	}
> +
> +	return NO_CSI2_PORT;
> +}

...

> +static struct fwnode_handle *get_mipi_port_handle(struct acpi_device *device,
> +						  unsigned int port)
> +{
> +	static const char mipi_port_prefix[] = "mipi-img-port-";
> +	char mipi_port_name[sizeof(mipi_port_prefix) + 2];

I think the following will be better:

	char mipi_port_name[16];


> +	if (snprintf(mipi_port_name, sizeof(mipi_port_name), "%s%u",
> +		     mipi_port_prefix, port) >= sizeof(mipi_port_name)) {

	if (snprintf(mipi_port_name, sizeof(mipi_port_name), "mipi-img-port-%u",
		     port) >= sizeof(mipi_port_name)) {

> +		acpi_handle_info(acpi_device_handle(device),
> +				 "mipi port name too long for port %u\n", port);
> +		return NULL;
> +	}
> +
> +	return fwnode_get_named_child_node(acpi_fwnode_handle(device),
> +					   mipi_port_name);
> +}

...

> +	union {
> +		u32 val;

OK. I stopped here, because I'm not sure you have really sent an updated
version. For sure the val and union is not used.

> +		/* Data lanes + the clock lane */
> +		u8 val8[BITS_TO_BYTES(ARRAY_SIZE(port->data_lanes) + 1)];
> +	} u;

...

Please, address all in v3.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v3 4/8] ACPI: property: Generate camera swnodes for ACPI and DisCo for Imaging

[Andy Shevchenko]

On Fri, Jan 27, 2023 at 12:35:13PM +0200, Andy Shevchenko wrote:
> On Thu, Jan 26, 2023 at 12:40:57AM +0200, Sakari Ailus wrote:

...

> Please, address all in v3.

I meant v4.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v3 1/8] ACPI: property: Parse data node string references in properties

[Rafael J. Wysocki]

On Wed, Jan 25, 2023 at 11:41 PM Sakari Ailus
<sakari.ailus@linux.intel.com> wrote:
>
> Add support for parsing property references using strings, besides
> reference objects that were previously supported. This allows also
> referencing data nodes which was not possible with reference objects.
>
> Also add pr_fmt() macro to prefix printouts.
>
> While at it, update copyright.
>
> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>

While there is some design documentation in the last patch, at least
some pieces of it should go into the changelog of this patch IMO.

Also the spec-related information from the cover letter would be
useful here, because cover letters don't go into the git record.

Re: [PATCH v3 2/8] ACPI: property: Parse _CRS CSI-2 descriptor

[Sakari Ailus]

Hi Andy,

Thank you for the review.

On Fri, Jan 27, 2023 at 12:08:39PM +0200, Andy Shevchenko wrote:
> On Thu, Jan 26, 2023 at 12:40:55AM +0200, Sakari Ailus wrote:
> > Parse newly added ACPI _CRS CSI-2 descriptor for CSI-2 and camera
> > configuration. For now, only figure out where the descriptor is present in
> > order to allow adding information from it to related devices.
> 
> ...
> 
> > +	if (status != AE_OK) {
> 
> ACPI_FAILURE()

Yes.

> 
> > +		acpi_handle_warn(inst_context->handle,
> > +				 "cannot get handle for %s\n",
> > +				 csi2->resource_source.string_ptr);
> > +		return AE_OK;
> > +	}
> 
> ...
> 
> > +	struct scan_check_crs_csi2_context inst_context = {
> > +		.handle = handle,
> > +		.res_list = LIST_HEAD_INIT(inst_context.res_list),
> > +	};
> > +	struct list_head *list = context;
> > +	struct crs_csi2 *csi2;
> 
> > +	INIT_LIST_HEAD(&inst_context.res_list);
> 
> Do you still need this?

Oops. Forgot to remove it, I'll do in v4.

> 
> ...
> 
> > +	acpi_walk_resources(handle, METHOD_NAME__CRS,
> > +			    scan_check_crs_csi2_instance, &inst_context);
> > +
> > +	if (list_empty(&inst_context.res_list))
> > +		return AE_OK;
> 
> I'm wondering if you can utilize acpi_dev_get_resources().

We don't have an acpi_device yet. I'd rather keep scanning for _CRS CSI2
resources here, as we'd otherwise have to split creating acpi_device's and
registering them into two.

I'd say if someone had implemented this like that, I'd ask them to change
it.

> 
> ...
> 
> > +	/* Collect the devices that have a _CRS CSI-2 resource */
> > +	acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, ACPI_UINT32_MAX,
> 
> Other serial buses limit the DEPTH by 32, why do we need more here?

I'm using the same value as for scanning devices to be added. Effectively
this is not a practical limit but it doesn't need to be.

> 
> > +			    scan_check_crs_csi2, NULL, &crs_csi2_handles, NULL);
> 
> ...
> 
> > +	sort(handle_refs, handle_count, sizeof(*handle_refs), crs_handle_cmp,
> > +	     NULL);
> 
> A single line?

Can do...

> 
> ...
> 
> > +		if (check_mul_overflow(sizeof(*ads->ports) +
> > +				       sizeof(*ads->nodes) * 2 +
> > +				       sizeof(*ads->nodeptrs) * 2,
> > +				       (size_t)this_count, &alloc_size) ||
> 
> So, now you know why this_count can't be type of size_t?

Forgot to change this one, thanks!

> 
> > +		    check_add_overflow(sizeof(*ads) + sizeof(*ads->nodes) +
> > +				       sizeof(*ads->nodeptrs) * 2,
> > +				       alloc_size, &alloc_size)) {
> > +			acpi_handle_warn(handle, "too many handles (%u)",
> > +					 this_count);
> > +			continue;
> > +		}
> 

-- 
Kind regards,

Sakari Ailus

Re: [PATCH v3 4/8] ACPI: property: Generate camera swnodes for ACPI and DisCo for Imaging

[Sakari Ailus]

Hi Andy,

On Fri, Jan 27, 2023 at 12:35:12PM +0200, Andy Shevchenko wrote:
> On Thu, Jan 26, 2023 at 12:40:57AM +0200, Sakari Ailus wrote:
> > Generate software nodes for information parsed from ACPI _CRS for CSI-2 as
> > well as MIPI DisCo for Imaging spec. The software nodes are compliant with
> > existing ACPI or DT definitions and are parsed by relevant drivers without
> > changes.
> 
> ...
> 
> > +static unsigned int next_csi2_port_index(struct acpi_device_software_nodes *ads,
> > +					 unsigned int port_nr)
> > +{
> > +	unsigned int i;
> > +
> > +	for (i = 0; i < ads->num_ports; i++) {
> > +		struct acpi_device_software_node_port *port = &ads->ports[i];
> > +
> > +		if (port->port_nr == port_nr)
> > +			return i;
> 
> > +		if (port->port_nr != NO_CSI2_PORT)
> > +			continue;
> > +
> > +		port->port_nr = port_nr;
> > +
> > +		return i;
> 
> Maybe it would be better to use the same pattern as above?
> 
> 		if (port->port_nr == NO_CSI2_PORT) {
> 			port->port_nr = port_nr;
> 			return i;
> 		}

Works for me...

> 
> > +	}
> > +
> > +	return NO_CSI2_PORT;
> > +}
> 
> ...
> 
> > +static struct fwnode_handle *get_mipi_port_handle(struct acpi_device *device,
> > +						  unsigned int port)
> > +{
> > +	static const char mipi_port_prefix[] = "mipi-img-port-";
> > +	char mipi_port_name[sizeof(mipi_port_prefix) + 2];
> 
> I think the following will be better:
> 
> 	char mipi_port_name[16];

If the array is too short, this will generate a warning but... this is
already handled better than that. Why not to keep it?

> 
> 
> > +	if (snprintf(mipi_port_name, sizeof(mipi_port_name), "%s%u",
> > +		     mipi_port_prefix, port) >= sizeof(mipi_port_name)) {
> 
> 	if (snprintf(mipi_port_name, sizeof(mipi_port_name), "mipi-img-port-%u",
> 		     port) >= sizeof(mipi_port_name)) {
> 
> > +		acpi_handle_info(acpi_device_handle(device),
> > +				 "mipi port name too long for port %u\n", port);
> > +		return NULL;
> > +	}
> > +
> > +	return fwnode_get_named_child_node(acpi_fwnode_handle(device),
> > +					   mipi_port_name);
> > +}
> 
> ...
> 
> > +	union {
> > +		u32 val;
> 
> OK. I stopped here, because I'm not sure you have really sent an updated
> version. For sure the val and union is not used.

Indeed. My apologies --- I missed making a few changes I intended to do.
I'll go through those once more and then send v4.

> 
> > +		/* Data lanes + the clock lane */
> > +		u8 val8[BITS_TO_BYTES(ARRAY_SIZE(port->data_lanes) + 1)];
> > +	} u;

-- 
Kind regards,

Sakari Ailus

Re: [PATCH v3 1/8] ACPI: property: Parse data node string references in properties

[Andy Shevchenko]

On Mon, Jan 30, 2023 at 07:21:12PM +0100, Rafael J. Wysocki wrote:
> On Wed, Jan 25, 2023 at 11:41 PM Sakari Ailus
> <sakari.ailus@linux.intel.com> wrote:
> >
> > Add support for parsing property references using strings, besides
> > reference objects that were previously supported. This allows also
> > referencing data nodes which was not possible with reference objects.
> >
> > Also add pr_fmt() macro to prefix printouts.
> >
> > While at it, update copyright.
> 
> While there is some design documentation in the last patch, at least
> some pieces of it should go into the changelog of this patch IMO.
> 
> Also the spec-related information from the cover letter would be
> useful here, because cover letters don't go into the git record.

Interestingly if a maintainer starts using `b4` tool it has the mode in which
the series is represented as a pull request and cover letter contents go as a
commit message into the merge commit. That said, it depends on the maintainer's
workflow.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v3 2/8] ACPI: property: Parse _CRS CSI-2 descriptor

[Andy Shevchenko]

On Mon, Jan 30, 2023 at 11:18:30PM +0200, Sakari Ailus wrote:
> On Fri, Jan 27, 2023 at 12:08:39PM +0200, Andy Shevchenko wrote:
> > On Thu, Jan 26, 2023 at 12:40:55AM +0200, Sakari Ailus wrote:

...

> > > +	/* Collect the devices that have a _CRS CSI-2 resource */
> > > +	acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, ACPI_UINT32_MAX,
> > 
> > Other serial buses limit the DEPTH by 32, why do we need more here?
> 
> I'm using the same value as for scanning devices to be added. Effectively
> this is not a practical limit but it doesn't need to be.

Hmm... Theoretically one may supply a malformed table, quite compact, but with
huge amount of "fake" devices. I would limit this the same way. If we got a
report of the depth not being enough we may bump based on the reality. This also
may limit scanning time.

> > > +			    scan_check_crs_csi2, NULL, &crs_csi2_handles, NULL);

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v3 4/8] ACPI: property: Generate camera swnodes for ACPI and DisCo for Imaging

[Andy Shevchenko]

On Mon, Jan 30, 2023 at 11:22:00PM +0200, Sakari Ailus wrote:
> On Fri, Jan 27, 2023 at 12:35:12PM +0200, Andy Shevchenko wrote:
> > On Thu, Jan 26, 2023 at 12:40:57AM +0200, Sakari Ailus wrote:

...

> > > +static struct fwnode_handle *get_mipi_port_handle(struct acpi_device *device,
> > > +						  unsigned int port)
> > > +{
> > > +	static const char mipi_port_prefix[] = "mipi-img-port-";
> > > +	char mipi_port_name[sizeof(mipi_port_prefix) + 2];
> > 
> > I think the following will be better:
> > 
> > 	char mipi_port_name[16];
> 
> If the array is too short, this will generate a warning but... this is
> already handled better than that. Why not to keep it?

We will get the format string self contained.

> > > +	if (snprintf(mipi_port_name, sizeof(mipi_port_name), "%s%u",
> > > +		     mipi_port_prefix, port) >= sizeof(mipi_port_name)) {
> > 
> > 	if (snprintf(mipi_port_name, sizeof(mipi_port_name), "mipi-img-port-%u",
> > 		     port) >= sizeof(mipi_port_name)) {
> > 
> > > +		acpi_handle_info(acpi_device_handle(device),
> > > +				 "mipi port name too long for port %u\n", port);
> > > +		return NULL;
> > > +	}
> > > +
> > > +	return fwnode_get_named_child_node(acpi_fwnode_handle(device),
> > > +					   mipi_port_name);
> > > +}

...

> > > +	union {
> > > +		u32 val;
> > 
> > OK. I stopped here, because I'm not sure you have really sent an updated
> > version. For sure the val and union is not used.
> 
> Indeed. My apologies --- I missed making a few changes I intended to do.
> I'll go through those once more and then send v4.

Thank you!

> > > +		/* Data lanes + the clock lane */
> > > +		u8 val8[BITS_TO_BYTES(ARRAY_SIZE(port->data_lanes) + 1)];
> > > +	} u;

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v3 2/8] ACPI: property: Parse _CRS CSI-2 descriptor

[Sakari Ailus]

On Mon, Jan 30, 2023 at 11:37:53PM +0200, Andy Shevchenko wrote:
> On Mon, Jan 30, 2023 at 11:18:30PM +0200, Sakari Ailus wrote:
> > On Fri, Jan 27, 2023 at 12:08:39PM +0200, Andy Shevchenko wrote:
> > > On Thu, Jan 26, 2023 at 12:40:55AM +0200, Sakari Ailus wrote:
> 
> ...
> 
> > > > +	/* Collect the devices that have a _CRS CSI-2 resource */
> > > > +	acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, ACPI_UINT32_MAX,
> > > 
> > > Other serial buses limit the DEPTH by 32, why do we need more here?
> > 
> > I'm using the same value as for scanning devices to be added. Effectively
> > this is not a practical limit but it doesn't need to be.
> 
> Hmm... Theoretically one may supply a malformed table, quite compact, but with
> huge amount of "fake" devices. I would limit this the same way. If we got a
> report of the depth not being enough we may bump based on the reality. This also
> may limit scanning time.

Then this should be done also for scanning ACPI devices below.

I'd like to have Rafael's opinion before making such changes. I'll prepend
such a patch to the series in that case.

-- 
Sakari Ailus

Re: [PATCH v3 4/8] ACPI: property: Generate camera swnodes for ACPI and DisCo for Imaging

[Sakari Ailus]

On Mon, Jan 30, 2023 at 11:39:45PM +0200, Andy Shevchenko wrote:
> On Mon, Jan 30, 2023 at 11:22:00PM +0200, Sakari Ailus wrote:
> > On Fri, Jan 27, 2023 at 12:35:12PM +0200, Andy Shevchenko wrote:
> > > On Thu, Jan 26, 2023 at 12:40:57AM +0200, Sakari Ailus wrote:
> 
> ...
> 
> > > > +static struct fwnode_handle *get_mipi_port_handle(struct acpi_device *device,
> > > > +						  unsigned int port)
> > > > +{
> > > > +	static const char mipi_port_prefix[] = "mipi-img-port-";
> > > > +	char mipi_port_name[sizeof(mipi_port_prefix) + 2];
> > > 
> > > I think the following will be better:
> > > 
> > > 	char mipi_port_name[16];
> > 
> > If the array is too short, this will generate a warning but... this is
> > already handled better than that. Why not to keep it?
> 
> We will get the format string self contained.

I have earlier stated as my opinion that it is a lesser concern.

> 
> > > > +	if (snprintf(mipi_port_name, sizeof(mipi_port_name), "%s%u",
> > > > +		     mipi_port_prefix, port) >= sizeof(mipi_port_name)) {

-- 
Sakari Ailus

Re: [PATCH v3 2/8] ACPI: property: Parse _CRS CSI-2 descriptor

[Rafael J. Wysocki]

On Wed, Jan 25, 2023 at 11:41 PM Sakari Ailus
<sakari.ailus@linux.intel.com> wrote:
>
> Parse newly added ACPI _CRS CSI-2 descriptor for CSI-2 and camera
> configuration. For now, only figure out where the descriptor is present in
> order to allow adding information from it to related devices.
>
> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> ---
>  drivers/acpi/Makefile   |   2 +-
>  drivers/acpi/internal.h |   7 +
>  drivers/acpi/mipi.c     | 320 ++++++++++++++++++++++++++++++++++++++++
>  drivers/acpi/scan.c     |  16 +-
>  include/acpi/acpi_bus.h |  11 ++
>  5 files changed, 351 insertions(+), 5 deletions(-)
>  create mode 100644 drivers/acpi/mipi.c
>
> diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
> index a5b649e71ab1b..a98fa1bc15548 100644
> --- a/drivers/acpi/Makefile
> +++ b/drivers/acpi/Makefile
> @@ -37,7 +37,7 @@ acpi-$(CONFIG_ACPI_SLEEP)     += proc.o
>  # ACPI Bus and Device Drivers
>  #
>  acpi-y                         += bus.o glue.o
> -acpi-y                         += scan.o
> +acpi-y                         += scan.o mipi.o
>  acpi-y                         += resource.o
>  acpi-y                         += acpi_processor.o
>  acpi-y                         += processor_core.o
> diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
> index ec584442fb298..1ec4aa92bf17a 100644
> --- a/drivers/acpi/internal.h
> +++ b/drivers/acpi/internal.h
> @@ -282,4 +282,11 @@ void acpi_init_lpit(void);
>  static inline void acpi_init_lpit(void) { }
>  #endif
>
> +/*--------------------------------------------------------------------------
> +                               ACPI and MIPI DisCo for Imaging conversion
> +  -------------------------------------------------------------------------- */
> +
> +void acpi_crs_csi2_swnodes_del_free(void);
> +void acpi_bus_scan_crs_csi2(acpi_handle handle);
> +
>  #endif /* _ACPI_INTERNAL_H_ */
> diff --git a/drivers/acpi/mipi.c b/drivers/acpi/mipi.c
> new file mode 100644
> index 0000000000000..269a6965d56e6
> --- /dev/null
> +++ b/drivers/acpi/mipi.c
> @@ -0,0 +1,320 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * MIPI DisCo for Imaging support.
> + *
> + * Copyright (C) 2023 Intel Corporation
> + */
> +
> +#include <linux/acpi.h>
> +#include <linux/list.h>
> +#include <linux/module.h>
> +#include <linux/overflow.h>
> +#include <linux/types.h>
> +#include <linux/slab.h>
> +#include <linux/sort.h>
> +#include <linux/string.h>
> +
> +#include "internal.h"
> +
> +struct crs_csi2_swnodes {
> +       struct list_head list;
> +       acpi_handle handle;
> +       struct acpi_device_software_nodes *ads;
> +};
> +
> +static LIST_HEAD(crs_csi2_swnodes);
> +
> +static void crs_csi2_swnode_del_free(struct crs_csi2_swnodes *swnodes)
> +{
> +       list_del(&swnodes->list);
> +       kfree(swnodes);
> +}
> +
> +void acpi_crs_csi2_swnodes_del_free(void)
> +{
> +       struct crs_csi2_swnodes *swnodes, *swnodes_tmp;
> +
> +       list_for_each_entry_safe(swnodes, swnodes_tmp, &crs_csi2_swnodes, list)
> +               crs_csi2_swnode_del_free(swnodes);
> +}
> +
> +struct crs_csi2_instance {
> +       struct list_head list;
> +       struct acpi_resource_csi2_serialbus csi2;
> +       acpi_handle remote_handle;
> +       char remote_name[];
> +};
> +
> +struct crs_csi2 {
> +       struct list_head list;
> +       acpi_handle handle;
> +       struct list_head buses;
> +};
> +
> +struct scan_check_crs_csi2_context {
> +       struct list_head res_list;
> +       acpi_handle handle;
> +};

All of the structures above need to be described, including what they
represent and what they are for.

> +
> +static acpi_status scan_check_crs_csi2_instance(struct acpi_resource *res,
> +                                               void *context)
> +{
> +       struct scan_check_crs_csi2_context *inst_context = context;
> +       struct acpi_resource_csi2_serialbus *csi2;
> +       struct crs_csi2_instance *inst;
> +       acpi_handle remote_handle;
> +       acpi_status status;
> +
> +       if (res->type != ACPI_RESOURCE_TYPE_SERIAL_BUS)
> +               return AE_OK;
> +
> +       csi2 = &res->data.csi2_serial_bus;
> +
> +       if (csi2->type != ACPI_RESOURCE_SERIAL_TYPE_CSI2)
> +               return AE_OK;
> +
> +       if (!csi2->resource_source.string_length) {
> +               acpi_handle_debug(inst_context->handle,
> +                                 "invalid resource source string length\n");
> +               return AE_OK;
> +       }
> +
> +       status = acpi_get_handle(NULL, csi2->resource_source.string_ptr,
> +                                &remote_handle);
> +       if (status != AE_OK) {
> +               acpi_handle_warn(inst_context->handle,
> +                                "cannot get handle for %s\n",
> +                                csi2->resource_source.string_ptr);
> +               return AE_OK;
> +       }

After this, remote_handle will be the ACPI handle of an ACPI object
representing a remote CSI-2 device IIUC.

> +
> +       inst = kmalloc(struct_size(inst, remote_name,

This line break is confusing.

> +                                  csi2->resource_source.string_length),
> +                      GFP_KERNEL);
> +       if (!inst)
> +               return AE_OK;
> +
> +       inst->csi2 = *csi2;

A pointer to the entire csi2 structure is stored in ints, so why is it
still necessary to copy remote_name and remote_handle extracted from
it to the additional fields?

> +       strscpy(inst->remote_name, csi2->resource_source.string_ptr,
> +               csi2->resource_source.string_length);
> +       inst->csi2.resource_source.string_ptr = inst->remote_name;
> +       inst->remote_handle = remote_handle;
> +
> +       list_add(&inst->list, &inst_context->res_list);

So this adds an entry to a list of "receivers" pointed to by the _CRS
for one "sender"?

> +
> +       return AE_OK;
> +}
> +
> +static acpi_status scan_check_crs_csi2(acpi_handle handle, u32 nesting_level,
> +                                      void *context, void **ret)
> +{
> +       struct scan_check_crs_csi2_context inst_context = {
> +               .handle = handle,
> +               .res_list = LIST_HEAD_INIT(inst_context.res_list),
> +       };
> +       struct list_head *list = context;
> +       struct crs_csi2 *csi2;
> +
> +       INIT_LIST_HEAD(&inst_context.res_list);
> +
> +       acpi_walk_resources(handle, METHOD_NAME__CRS,
> +                           scan_check_crs_csi2_instance, &inst_context);
> +
> +       if (list_empty(&inst_context.res_list))
> +               return AE_OK;

At this point inst_context.res_list is a list of remote "receivers"
pointed to by all of the CSI-2 _CRS entries for the device represented
by @handle?

> +
> +       csi2 = kmalloc(sizeof(*csi2), GFP_KERNEL);
> +       if (!csi2)
> +               return AE_OK;
> +
> +       csi2->handle = handle;
> +       list_replace(&inst_context.res_list, &csi2->buses);

And here, csi2 represents a "sender" device along with a list of
"receiver" devices pointed to by its CSI-2 _CRS entries, right?

> +       list_add(&csi2->list, list);
> +
> +       return AE_OK;
> +}
> +
> +struct acpi_handle_ref {
> +       acpi_handle handle;
> +       unsigned int count;
> +};
> +
> +#define NO_CSI2_PORT (~1U)
> +
> +static int crs_handle_cmp(const void *__a, const void *__b)
> +{
> +       const struct acpi_handle_ref *a = __a, *b = __b;
> +
> +       return a->handle < b->handle ? -1 : a->handle > b->handle;
> +}
> +
> +static void crs_csi2_release(struct list_head *crs_csi2_handles)
> +{
> +       struct crs_csi2 *csi2, *csi2_tmp;
> +
> +       list_for_each_entry_safe(csi2, csi2_tmp, crs_csi2_handles, list) {
> +               struct crs_csi2_instance *inst, *inst_tmp;
> +
> +               list_for_each_entry_safe(inst, inst_tmp, &csi2->buses, list) {
> +                       list_del(&inst->list);
> +                       kfree(inst);
> +               }
> +
> +               list_del(&csi2->list);
> +               kfree(csi2);
> +       }
> +}

So far, not even a word of description of what's going on.

> +
> +/**
> + * acpi_bus_scan_crs_csi2 - Scan a device and its child devices for _CRS CSI-2
> + *
> + * @handle: ACPI handle to scan

"Root of the ACPI Namespace branch to scan"

> + *
> + * This function does a number of things:
> + *
> + * 1. Scan an ACPI device and its children for _CRS CSI-2 instances. The
> + *    instances are stored for later use.

This is not just the children, but everything under @handle, because
the callback doesn't terminate the walk.

And if @handle happens to be the ACPI Namespace root, the function
will scan all of it AFAICS.

> + *
> + * 2. Count how many references to other devices _CRS CSI-2 instances have in
> + *    total.
> + *
> + * 3. Count the number of references to other devices for each _CRS CSI-2
> + *    instance.
> + *
> + * 4. Allocate memory for swnodes each ACPI device requires later on, and
> + *    generate a list of such allocations.
> + *
> + * Note that struct acpi_device isn't available yet at this time.

Why exactly can't this be done after the struct acpi_device objects
have been created, but before binding any drivers etc to them?

> + *
> + * acpi_scan_lock in scan.c must be held when calling this function.
> + */
> +void acpi_bus_scan_crs_csi2(acpi_handle handle)
> +{
> +       struct acpi_handle_ref *handle_refs;
> +       struct acpi_handle_ref *this = NULL;
> +       LIST_HEAD(crs_csi2_handles);
> +       unsigned int handle_count = 0, this_count;
> +       unsigned int curr = 0;
> +       struct crs_csi2 *csi2;
> +
> +       /* Collect the devices that have a _CRS CSI-2 resource */
> +       acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, ACPI_UINT32_MAX,
> +                           scan_check_crs_csi2, NULL, &crs_csi2_handles, NULL);

So the result of this will be a list of "senders" where each entry
represents one device along with a list of remote "receivers"
connected to it.  Is this correct?

> +
> +       /*
> +        * Figure out how much temporary storage we need for counting
> +        * connections in each device.
> +        */
> +       list_for_each_entry(csi2, &crs_csi2_handles, list) {
> +               struct crs_csi2_instance *inst;
> +
> +               handle_count++;
> +
> +               list_for_each_entry(inst, &csi2->buses, list)
> +                       handle_count++;
> +       }

I would suggest counting stuff while creating the data structure, so
this extra walk would not be necessary.

> +
> +       /* No handles? Bail out here. */
> +       if (!handle_count)
> +               return;
> +
> +       handle_refs = kcalloc(handle_count + 1, sizeof(*handle_refs),
> +                             GFP_KERNEL);
> +       if (!handle_refs) {
> +               acpi_handle_debug(handle, "no memory for %u handle refs\n",
> +                                 handle_count + 1);
> +               return;
> +       }
> +
> +       /* Associate handles to the number of references. */
> +       list_for_each_entry(csi2, &crs_csi2_handles, list) {
> +               struct crs_csi2_instance *inst;
> +               struct acpi_handle_ref *handle_ref;
> +
> +               handle_ref = &handle_refs[curr++];
> +               handle_ref->handle = csi2->handle;
> +
> +               list_for_each_entry(inst, &csi2->buses, list) {
> +                       handle_refs[curr].handle = inst->remote_handle;
> +                       handle_refs[curr].count = 1;
> +                       handle_ref->count++;
> +                       curr++;
> +               }
> +       }
> +
> +       handle_refs[curr].handle = NULL;

So the above basically creates a flat array of entries that each
contain an ACPI handle of (an ACPI object representing) a CSI-2 device
and the number of other CSI-2 devices that it can talk to.

But one device can appear in multiple entries, which is why it is
sorted below and then the entries corresponding to one device are
aggregated.

> +
> +       sort(handle_refs, handle_count, sizeof(*handle_refs), crs_handle_cmp,
> +            NULL);
> +
> +       /*
> +        * Finally count references in each handle, allocate space for device
> +        * specific ports, properties and fill the _CRS CSI2 descriptor
> +        * originated data.
> +        */
> +       this = handle_refs;
> +       this_count = this->count;
> +       for (curr = 1; curr < handle_count + 1; curr++) {
> +               struct acpi_device_software_nodes *ads;
> +               struct crs_csi2_swnodes *swnodes;
> +               size_t alloc_size;
> +               void *end;
> +
> +               if (this->handle == handle_refs[curr].handle) {
> +                       this_count += handle_refs[curr].count;
> +                       continue;
> +               }
> +
> +               /*
> +                * Allocate memory for ports, node pointers (number of nodes +
> +                * 1 (guardian), nodes (root + number of ports * 2 (for for
> +                * every port there is an endpoint)).
> +                */
> +               if (check_mul_overflow(sizeof(*ads->ports) +
> +                                      sizeof(*ads->nodes) * 2 +
> +                                      sizeof(*ads->nodeptrs) * 2,
> +                                      (size_t)this_count, &alloc_size) ||
> +                   check_add_overflow(sizeof(*ads) + sizeof(*ads->nodes) +
> +                                      sizeof(*ads->nodeptrs) * 2,
> +                                      alloc_size, &alloc_size)) {

Please try to split this conditional into smaller pieces.  As is, it
is almost completely unreadable.

> +                       acpi_handle_warn(handle, "too many handles (%u)",
> +                                        this_count);

And the warning is utterly useless except for debugging.

> +                       continue;
> +               }
> +
> +               swnodes = kzalloc(sizeof(*swnodes), GFP_KERNEL);
> +               ads = kzalloc(alloc_size, GFP_KERNEL);
> +               ads->ports = (void *)(ads + 1);
> +               ads->nodes = (void *)(ads->ports + this_count);
> +               ads->nodeptrs = (void *)(ads->nodes +
> +                                        this_count * 2 + 1);
> +               end = ads->nodeptrs + this_count * 2 + 2;
> +               if (!swnodes || !ads ||
> +                   WARN_ON((void *)ads + alloc_size != end)) {

Why WARN_ON()?  Is this so important?

> +                       kfree(swnodes);
> +                       kfree(ads);
> +                       acpi_handle_debug(handle,
> +                                         "cannot allocate for %u swnodes\n",

Say "software nodes" in the message and please mention CSI-2 in it too.

> +                                         this_count);
> +               } else {
> +                       unsigned int i;
> +
> +                       ads->num_ports = this_count;
> +                       for (i = 0; i < this_count * 2 + 1; i++)
> +                               ads->nodeptrs[i] = &ads->nodes[i];
> +                       ads->nodeptrs[i] = NULL;
> +                       for (i = 0; i < this_count; i++)
> +                               ads->ports[i].port_nr = NO_CSI2_PORT;
> +                       swnodes->handle = this->handle;
> +                       swnodes->ads = ads;
> +                       list_add(&swnodes->list, &crs_csi2_swnodes);
> +               }

The allocation part above can be done in a separate function with a
description of what's going on.

It is really hard to figure out what happens here from the code and it
shouldn't even be necessary.  Please explain what you are doing.

> +
> +               this = &handle_refs[curr];
> +               this_count = this->count;
> +       }
> +
> +       kfree(handle_refs);
> +
> +       crs_csi2_release(&crs_csi2_handles);
> +}
> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> index 0c6f06abe3f47..50de874b8f208 100644
> --- a/drivers/acpi/scan.c
> +++ b/drivers/acpi/scan.c
> @@ -2423,9 +2423,12 @@ EXPORT_SYMBOL_GPL(acpi_dev_get_next_consumer_dev);
>  int acpi_bus_scan(acpi_handle handle)
>  {
>         struct acpi_device *device = NULL;
> +       int ret = 0;
>
>         acpi_bus_scan_second_pass = false;
>
> +       acpi_bus_scan_crs_csi2(handle);
> +

This effectively adds an extra walk over the entire ACPI Namespace
which is pure useless overhead on systems without CSI-2 descriptors.

I'm predicting that server people who care about boot times won't like it.

>         /* Pass 1: Avoid enumerating devices with missing dependencies. */
>
>         if (ACPI_SUCCESS(acpi_bus_check_add(handle, true, &device)))
> @@ -2433,13 +2436,15 @@ int acpi_bus_scan(acpi_handle handle)
>                                     acpi_bus_check_add_1, NULL, NULL,
>                                     (void **)&device);
>
> -       if (!device)
> -               return -ENODEV;
> +       if (!device) {
> +               ret = -ENODEV;
> +               goto out_release;
> +       }
>
>         acpi_bus_attach(device, (void *)true);
>
>         if (!acpi_bus_scan_second_pass)
> -               return 0;
> +               goto out_release;
>
>         /* Pass 2: Enumerate all of the remaining devices. */
>
> @@ -2452,7 +2457,10 @@ int acpi_bus_scan(acpi_handle handle)
>
>         acpi_bus_attach(device, NULL);
>
> -       return 0;
> +out_release:
> +       acpi_crs_csi2_swnodes_del_free();
> +
> +       return ret;
>  }
>  EXPORT_SYMBOL(acpi_bus_scan);
>
> diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
> index e44be31115a67..a05fe22c1175c 100644
> --- a/include/acpi/acpi_bus.h
> +++ b/include/acpi/acpi_bus.h
> @@ -360,6 +360,17 @@ struct acpi_device_data {
>
>  struct acpi_gpio_mapping;
>
> +struct acpi_device_software_node_port {
> +       unsigned int port_nr;
> +};
> +
> +struct acpi_device_software_nodes {
> +       struct acpi_device_software_node_port *ports;
> +       struct software_node *nodes;
> +       const struct software_node **nodeptrs;
> +       unsigned int num_ports;
> +};

No description?

> +
>  /* Device */
>  struct acpi_device {
>         u32 pld_crc;
> --

Re: [PATCH v3 2/8] ACPI: property: Parse _CRS CSI-2 descriptor

[Sakari Ailus]

Hi Rafael,

Thank you for the review.

On Thu, Feb 02, 2023 at 08:57:04PM +0100, Rafael J. Wysocki wrote:
> On Wed, Jan 25, 2023 at 11:41 PM Sakari Ailus
> <sakari.ailus@linux.intel.com> wrote:
> >
> > Parse newly added ACPI _CRS CSI-2 descriptor for CSI-2 and camera
> > configuration. For now, only figure out where the descriptor is present in
> > order to allow adding information from it to related devices.
> >
> > Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> > ---
> >  drivers/acpi/Makefile   |   2 +-
> >  drivers/acpi/internal.h |   7 +
> >  drivers/acpi/mipi.c     | 320 ++++++++++++++++++++++++++++++++++++++++
> >  drivers/acpi/scan.c     |  16 +-
> >  include/acpi/acpi_bus.h |  11 ++
> >  5 files changed, 351 insertions(+), 5 deletions(-)
> >  create mode 100644 drivers/acpi/mipi.c
> >
> > diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
> > index a5b649e71ab1b..a98fa1bc15548 100644
> > --- a/drivers/acpi/Makefile
> > +++ b/drivers/acpi/Makefile
> > @@ -37,7 +37,7 @@ acpi-$(CONFIG_ACPI_SLEEP)     += proc.o
> >  # ACPI Bus and Device Drivers
> >  #
> >  acpi-y                         += bus.o glue.o
> > -acpi-y                         += scan.o
> > +acpi-y                         += scan.o mipi.o
> >  acpi-y                         += resource.o
> >  acpi-y                         += acpi_processor.o
> >  acpi-y                         += processor_core.o
> > diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
> > index ec584442fb298..1ec4aa92bf17a 100644
> > --- a/drivers/acpi/internal.h
> > +++ b/drivers/acpi/internal.h
> > @@ -282,4 +282,11 @@ void acpi_init_lpit(void);
> >  static inline void acpi_init_lpit(void) { }
> >  #endif
> >
> > +/*--------------------------------------------------------------------------
> > +                               ACPI and MIPI DisCo for Imaging conversion
> > +  -------------------------------------------------------------------------- */
> > +
> > +void acpi_crs_csi2_swnodes_del_free(void);
> > +void acpi_bus_scan_crs_csi2(acpi_handle handle);
> > +
> >  #endif /* _ACPI_INTERNAL_H_ */
> > diff --git a/drivers/acpi/mipi.c b/drivers/acpi/mipi.c
> > new file mode 100644
> > index 0000000000000..269a6965d56e6
> > --- /dev/null
> > +++ b/drivers/acpi/mipi.c
> > @@ -0,0 +1,320 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * MIPI DisCo for Imaging support.
> > + *
> > + * Copyright (C) 2023 Intel Corporation
> > + */
> > +
> > +#include <linux/acpi.h>
> > +#include <linux/list.h>
> > +#include <linux/module.h>
> > +#include <linux/overflow.h>
> > +#include <linux/types.h>
> > +#include <linux/slab.h>
> > +#include <linux/sort.h>
> > +#include <linux/string.h>
> > +
> > +#include "internal.h"
> > +
> > +struct crs_csi2_swnodes {
> > +       struct list_head list;
> > +       acpi_handle handle;
> > +       struct acpi_device_software_nodes *ads;
> > +};
> > +
> > +static LIST_HEAD(crs_csi2_swnodes);
> > +
> > +static void crs_csi2_swnode_del_free(struct crs_csi2_swnodes *swnodes)
> > +{
> > +       list_del(&swnodes->list);
> > +       kfree(swnodes);
> > +}
> > +
> > +void acpi_crs_csi2_swnodes_del_free(void)
> > +{
> > +       struct crs_csi2_swnodes *swnodes, *swnodes_tmp;
> > +
> > +       list_for_each_entry_safe(swnodes, swnodes_tmp, &crs_csi2_swnodes, list)
> > +               crs_csi2_swnode_del_free(swnodes);
> > +}
> > +
> > +struct crs_csi2_instance {
> > +       struct list_head list;
> > +       struct acpi_resource_csi2_serialbus csi2;
> > +       acpi_handle remote_handle;
> > +       char remote_name[];
> > +};
> > +
> > +struct crs_csi2 {
> > +       struct list_head list;
> > +       acpi_handle handle;
> > +       struct list_head buses;
> > +};
> > +
> > +struct scan_check_crs_csi2_context {
> > +       struct list_head res_list;
> > +       acpi_handle handle;
> > +};
> 
> All of the structures above need to be described, including what they
> represent and what they are for.

I'll add comments explaining what these are for.

> 
> > +
> > +static acpi_status scan_check_crs_csi2_instance(struct acpi_resource *res,
> > +                                               void *context)
> > +{
> > +       struct scan_check_crs_csi2_context *inst_context = context;
> > +       struct acpi_resource_csi2_serialbus *csi2;
> > +       struct crs_csi2_instance *inst;
> > +       acpi_handle remote_handle;
> > +       acpi_status status;
> > +
> > +       if (res->type != ACPI_RESOURCE_TYPE_SERIAL_BUS)
> > +               return AE_OK;
> > +
> > +       csi2 = &res->data.csi2_serial_bus;
> > +
> > +       if (csi2->type != ACPI_RESOURCE_SERIAL_TYPE_CSI2)
> > +               return AE_OK;
> > +
> > +       if (!csi2->resource_source.string_length) {
> > +               acpi_handle_debug(inst_context->handle,
> > +                                 "invalid resource source string length\n");
> > +               return AE_OK;
> > +       }
> > +
> > +       status = acpi_get_handle(NULL, csi2->resource_source.string_ptr,
> > +                                &remote_handle);
> > +       if (status != AE_OK) {
> > +               acpi_handle_warn(inst_context->handle,
> > +                                "cannot get handle for %s\n",
> > +                                csi2->resource_source.string_ptr);
> > +               return AE_OK;
> > +       }
> 
> After this, remote_handle will be the ACPI handle of an ACPI object
> representing a remote CSI-2 device IIUC.

Yes.

> 
> > +
> > +       inst = kmalloc(struct_size(inst, remote_name,
> 
> This line break is confusing.

I can unwrap it, resulting a rather long line, but I guess that's not an
issue.

> 
> > +                                  csi2->resource_source.string_length),
> > +                      GFP_KERNEL);
> > +       if (!inst)
> > +               return AE_OK;
> > +
> > +       inst->csi2 = *csi2;
> 
> A pointer to the entire csi2 structure is stored in ints, so why is it
> still necessary to copy remote_name and remote_handle extracted from
> it to the additional fields?

csi2->resource_source.string_ptr is a pointer pointing somewhere else (DSDT
binary I suppose?) and we're making a local copy of that here. The purpose
is to not rely on this memory being available later on.

> 
> > +       strscpy(inst->remote_name, csi2->resource_source.string_ptr,
> > +               csi2->resource_source.string_length);
> > +       inst->csi2.resource_source.string_ptr = inst->remote_name;
> > +       inst->remote_handle = remote_handle;
> > +
> > +       list_add(&inst->list, &inst_context->res_list);
> 
> So this adds an entry to a list of "receivers" pointed to by the _CRS
> for one "sender"?

Correct. (Usually "transmitter" is used in this context, but same thing.)

> 
> > +
> > +       return AE_OK;
> > +}
> > +
> > +static acpi_status scan_check_crs_csi2(acpi_handle handle, u32 nesting_level,
> > +                                      void *context, void **ret)
> > +{
> > +       struct scan_check_crs_csi2_context inst_context = {
> > +               .handle = handle,
> > +               .res_list = LIST_HEAD_INIT(inst_context.res_list),
> > +       };
> > +       struct list_head *list = context;
> > +       struct crs_csi2 *csi2;
> > +
> > +       INIT_LIST_HEAD(&inst_context.res_list);
> > +
> > +       acpi_walk_resources(handle, METHOD_NAME__CRS,
> > +                           scan_check_crs_csi2_instance, &inst_context);
> > +
> > +       if (list_empty(&inst_context.res_list))
> > +               return AE_OK;
> 
> At this point inst_context.res_list is a list of remote "receivers"
> pointed to by all of the CSI-2 _CRS entries for the device represented
> by @handle?

Yes.

> 
> > +
> > +       csi2 = kmalloc(sizeof(*csi2), GFP_KERNEL);
> > +       if (!csi2)
> > +               return AE_OK;
> > +
> > +       csi2->handle = handle;
> > +       list_replace(&inst_context.res_list, &csi2->buses);
> 
> And here, csi2 represents a "sender" device along with a list of
> "receiver" devices pointed to by its CSI-2 _CRS entries, right?

Yes. I can add comments detailing this.

> 
> > +       list_add(&csi2->list, list);
> > +
> > +       return AE_OK;
> > +}
> > +
> > +struct acpi_handle_ref {
> > +       acpi_handle handle;
> > +       unsigned int count;
> > +};
> > +
> > +#define NO_CSI2_PORT (~1U)
> > +
> > +static int crs_handle_cmp(const void *__a, const void *__b)
> > +{
> > +       const struct acpi_handle_ref *a = __a, *b = __b;
> > +
> > +       return a->handle < b->handle ? -1 : a->handle > b->handle;
> > +}
> > +
> > +static void crs_csi2_release(struct list_head *crs_csi2_handles)
> > +{
> > +       struct crs_csi2 *csi2, *csi2_tmp;
> > +
> > +       list_for_each_entry_safe(csi2, csi2_tmp, crs_csi2_handles, list) {
> > +               struct crs_csi2_instance *inst, *inst_tmp;
> > +
> > +               list_for_each_entry_safe(inst, inst_tmp, &csi2->buses, list) {
> > +                       list_del(&inst->list);
> > +                       kfree(inst);
> > +               }
> > +
> > +               list_del(&csi2->list);
> > +               kfree(csi2);
> > +       }
> > +}
> 
> So far, not even a word of description of what's going on.
> 
> > +
> > +/**
> > + * acpi_bus_scan_crs_csi2 - Scan a device and its child devices for _CRS CSI-2
> > + *
> > + * @handle: ACPI handle to scan
> 
> "Root of the ACPI Namespace branch to scan"

Yes...

> 
> > + *
> > + * This function does a number of things:
> > + *
> > + * 1. Scan an ACPI device and its children for _CRS CSI-2 instances. The
> > + *    instances are stored for later use.
> 
> This is not just the children, but everything under @handle, because
> the callback doesn't terminate the walk.
> 
> And if @handle happens to be the ACPI Namespace root, the function
> will scan all of it AFAICS.

Correct. I'll change this to convey the traversal isn't about immediate
children only.

> 
> > + *
> > + * 2. Count how many references to other devices _CRS CSI-2 instances have in
> > + *    total.
> > + *
> > + * 3. Count the number of references to other devices for each _CRS CSI-2
> > + *    instance.
> > + *
> > + * 4. Allocate memory for swnodes each ACPI device requires later on, and
> > + *    generate a list of such allocations.
> > + *
> > + * Note that struct acpi_device isn't available yet at this time.
> 
> Why exactly can't this be done after the struct acpi_device objects
> have been created, but before binding any drivers etc to them?

It could be done, yes, but you'd have to create all acpi_device objects
before any of them may get probed. The data is gathered one _CRS CSI2
descriptor at a time and all remote devices aren't knon before all have
been parsed.

> 
> > + *
> > + * acpi_scan_lock in scan.c must be held when calling this function.
> > + */
> > +void acpi_bus_scan_crs_csi2(acpi_handle handle)
> > +{
> > +       struct acpi_handle_ref *handle_refs;
> > +       struct acpi_handle_ref *this = NULL;
> > +       LIST_HEAD(crs_csi2_handles);
> > +       unsigned int handle_count = 0, this_count;
> > +       unsigned int curr = 0;
> > +       struct crs_csi2 *csi2;
> > +
> > +       /* Collect the devices that have a _CRS CSI-2 resource */
> > +       acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, ACPI_UINT32_MAX,
> > +                           scan_check_crs_csi2, NULL, &crs_csi2_handles, NULL);
> 
> So the result of this will be a list of "senders" where each entry
> represents one device along with a list of remote "receivers"
> connected to it.  Is this correct?

Correct.

> 
> > +
> > +       /*
> > +        * Figure out how much temporary storage we need for counting
> > +        * connections in each device.
> > +        */
> > +       list_for_each_entry(csi2, &crs_csi2_handles, list) {
> > +               struct crs_csi2_instance *inst;
> > +
> > +               handle_count++;
> > +
> > +               list_for_each_entry(inst, &csi2->buses, list)
> > +                       handle_count++;
> > +       }
> 
> I would suggest counting stuff while creating the data structure, so
> this extra walk would not be necessary.

Note that the number of entries in these lists is typically small, no more
than 20 in total, so this isn't really taking much time. But I believe the
counting can be done equally sell elsewhere, too, if you prefer that.

> 
> > +
> > +       /* No handles? Bail out here. */
> > +       if (!handle_count)
> > +               return;
> > +
> > +       handle_refs = kcalloc(handle_count + 1, sizeof(*handle_refs),
> > +                             GFP_KERNEL);
> > +       if (!handle_refs) {
> > +               acpi_handle_debug(handle, "no memory for %u handle refs\n",
> > +                                 handle_count + 1);
> > +               return;
> > +       }
> > +
> > +       /* Associate handles to the number of references. */
> > +       list_for_each_entry(csi2, &crs_csi2_handles, list) {
> > +               struct crs_csi2_instance *inst;
> > +               struct acpi_handle_ref *handle_ref;
> > +
> > +               handle_ref = &handle_refs[curr++];
> > +               handle_ref->handle = csi2->handle;
> > +
> > +               list_for_each_entry(inst, &csi2->buses, list) {
> > +                       handle_refs[curr].handle = inst->remote_handle;
> > +                       handle_refs[curr].count = 1;
> > +                       handle_ref->count++;
> > +                       curr++;
> > +               }
> > +       }
> > +
> > +       handle_refs[curr].handle = NULL;
> 
> So the above basically creates a flat array of entries that each
> contain an ACPI handle of (an ACPI object representing) a CSI-2 device
> and the number of other CSI-2 devices that it can talk to.
> 
> But one device can appear in multiple entries, which is why it is
> sorted below and then the entries corresponding to one device are
> aggregated.

Correct.

> 
> > +
> > +       sort(handle_refs, handle_count, sizeof(*handle_refs), crs_handle_cmp,
> > +            NULL);
> > +
> > +       /*
> > +        * Finally count references in each handle, allocate space for device
> > +        * specific ports, properties and fill the _CRS CSI2 descriptor
> > +        * originated data.
> > +        */
> > +       this = handle_refs;
> > +       this_count = this->count;
> > +       for (curr = 1; curr < handle_count + 1; curr++) {
> > +               struct acpi_device_software_nodes *ads;
> > +               struct crs_csi2_swnodes *swnodes;
> > +               size_t alloc_size;
> > +               void *end;
> > +
> > +               if (this->handle == handle_refs[curr].handle) {
> > +                       this_count += handle_refs[curr].count;
> > +                       continue;
> > +               }
> > +
> > +               /*
> > +                * Allocate memory for ports, node pointers (number of nodes +
> > +                * 1 (guardian), nodes (root + number of ports * 2 (for for
> > +                * every port there is an endpoint)).
> > +                */
> > +               if (check_mul_overflow(sizeof(*ads->ports) +
> > +                                      sizeof(*ads->nodes) * 2 +
> > +                                      sizeof(*ads->nodeptrs) * 2,
> > +                                      (size_t)this_count, &alloc_size) ||
> > +                   check_add_overflow(sizeof(*ads) + sizeof(*ads->nodes) +
> > +                                      sizeof(*ads->nodeptrs) * 2,
> > +                                      alloc_size, &alloc_size)) {
> 
> Please try to split this conditional into smaller pieces.  As is, it
> is almost completely unreadable.

Yes.

> 
> > +                       acpi_handle_warn(handle, "too many handles (%u)",
> > +                                        this_count);
> 
> And the warning is utterly useless except for debugging.

It is there exactly for that purpose. Although this isn't a serious matter
as such, it is very likely to signal of a bug (most likely in the code).

> 
> > +                       continue;
> > +               }
> > +
> > +               swnodes = kzalloc(sizeof(*swnodes), GFP_KERNEL);
> > +               ads = kzalloc(alloc_size, GFP_KERNEL);
> > +               ads->ports = (void *)(ads + 1);
> > +               ads->nodes = (void *)(ads->ports + this_count);
> > +               ads->nodeptrs = (void *)(ads->nodes +
> > +                                        this_count * 2 + 1);
> > +               end = ads->nodeptrs + this_count * 2 + 2;
> > +               if (!swnodes || !ads ||
> > +                   WARN_ON((void *)ads + alloc_size != end)) {
> 
> Why WARN_ON()?  Is this so important?

Sanity check. There are two allocations there with a different lifetime,
and the size of the other one is somewhat complicated to calculate.

> 
> > +                       kfree(swnodes);
> > +                       kfree(ads);
> > +                       acpi_handle_debug(handle,
> > +                                         "cannot allocate for %u swnodes\n",
> 
> Say "software nodes" in the message and please mention CSI-2 in it too.

Yes...

> 
> > +                                         this_count);
> > +               } else {
> > +                       unsigned int i;
> > +
> > +                       ads->num_ports = this_count;
> > +                       for (i = 0; i < this_count * 2 + 1; i++)
> > +                               ads->nodeptrs[i] = &ads->nodes[i];
> > +                       ads->nodeptrs[i] = NULL;
> > +                       for (i = 0; i < this_count; i++)
> > +                               ads->ports[i].port_nr = NO_CSI2_PORT;
> > +                       swnodes->handle = this->handle;
> > +                       swnodes->ads = ads;
> > +                       list_add(&swnodes->list, &crs_csi2_swnodes);
> > +               }
> 
> The allocation part above can be done in a separate function with a
> description of what's going on.
> 
> It is really hard to figure out what happens here from the code and it
> shouldn't even be necessary.  Please explain what you are doing.
> 
> > +
> > +               this = &handle_refs[curr];
> > +               this_count = this->count;
> > +       }
> > +
> > +       kfree(handle_refs);
> > +
> > +       crs_csi2_release(&crs_csi2_handles);
> > +}
> > diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> > index 0c6f06abe3f47..50de874b8f208 100644
> > --- a/drivers/acpi/scan.c
> > +++ b/drivers/acpi/scan.c
> > @@ -2423,9 +2423,12 @@ EXPORT_SYMBOL_GPL(acpi_dev_get_next_consumer_dev);
> >  int acpi_bus_scan(acpi_handle handle)
> >  {
> >         struct acpi_device *device = NULL;
> > +       int ret = 0;
> >
> >         acpi_bus_scan_second_pass = false;
> >
> > +       acpi_bus_scan_crs_csi2(handle);
> > +
> 
> This effectively adds an extra walk over the entire ACPI Namespace
> which is pure useless overhead on systems without CSI-2 descriptors.
> 
> I'm predicting that server people who care about boot times won't like it.

I'm certainly fine with doing this with fewer walks, but it requires
parsing the _CRS objects (as earlier in the patch) during the same
traversal than devices are created. But any driver probing must be
postponed after this traversal so we have found all the devices with CSI-2
connections (and created software nodes for them).

This is so by design, only one end of a connection has any information
about it.

> 
> >         /* Pass 1: Avoid enumerating devices with missing dependencies. */
> >
> >         if (ACPI_SUCCESS(acpi_bus_check_add(handle, true, &device)))
> > @@ -2433,13 +2436,15 @@ int acpi_bus_scan(acpi_handle handle)
> >                                     acpi_bus_check_add_1, NULL, NULL,
> >                                     (void **)&device);
> >
> > -       if (!device)
> > -               return -ENODEV;
> > +       if (!device) {
> > +               ret = -ENODEV;
> > +               goto out_release;
> > +       }
> >
> >         acpi_bus_attach(device, (void *)true);
> >
> >         if (!acpi_bus_scan_second_pass)
> > -               return 0;
> > +               goto out_release;
> >
> >         /* Pass 2: Enumerate all of the remaining devices. */
> >
> > @@ -2452,7 +2457,10 @@ int acpi_bus_scan(acpi_handle handle)
> >
> >         acpi_bus_attach(device, NULL);
> >
> > -       return 0;
> > +out_release:
> > +       acpi_crs_csi2_swnodes_del_free();
> > +
> > +       return ret;
> >  }
> >  EXPORT_SYMBOL(acpi_bus_scan);
> >
> > diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
> > index e44be31115a67..a05fe22c1175c 100644
> > --- a/include/acpi/acpi_bus.h
> > +++ b/include/acpi/acpi_bus.h
> > @@ -360,6 +360,17 @@ struct acpi_device_data {
> >
> >  struct acpi_gpio_mapping;
> >
> > +struct acpi_device_software_node_port {
> > +       unsigned int port_nr;
> > +};
> > +
> > +struct acpi_device_software_nodes {
> > +       struct acpi_device_software_node_port *ports;
> > +       struct software_node *nodes;
> > +       const struct software_node **nodeptrs;
> > +       unsigned int num_ports;
> > +};
> 
> No description?

None of the structs in that file (or generally elsewhere in vicinity) have
any helpful comments so I was just following a pattern. :-) But perhaps
these would deserve some. I can add them here, and see if other places
could benefit from them as well (plus your comments earlier in the patch).

> 
> > +
> >  /* Device */
> >  struct acpi_device {
> >         u32 pld_crc;
> > --

-- 
Kind regards,

Sakari Ailus