RE: [PATCH v2 5/5] ACPI: Drop parent field from struct acpi_device

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From: Rafael J. Wysocki <rjw@xxxxxxxxxxxxx> Sent: Wednesday, August 24, 2022 10:00 AM
> 
> The parent field in struct acpi_device is, in fact, redundant,
> because the dev.parent field in it effectively points to the same
> object and it is used by the driver core.
> 
> Accordingly, the parent field can be dropped from struct acpi_device
> and for this purpose define acpi_dev_parent() to retrieve a parent
> struct acpi_device pointer from the dev.parent field in struct
> acpi_device.  Next, update all of the users of the parent field
> in struct acpi_device to use acpi_dev_parent() instead of it and
> drop it.
> 
> While at it, drop the ACPI_IS_ROOT_DEVICE() macro that is only used
> in one place in a confusing way.
> 
> No intentional functional impact.
> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> Acked-by: Mark Brown <broonie@xxxxxxxxxx>
> Acked-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
> Acked-by: Wei Liu <wei.liu@xxxxxxxxxx>
> Reviewed-by: Punit Agrawal <punit.agrawal@xxxxxxxxxxxxx>

Tested the full patch series in Azure VMs running on Hyper-V --
one x86/x64 and one ARM64.  Testing includes standard VMbus
devices as well as virtual PCI devices (Mellanox CX-5 Virtual
Function).   Verified that ACPI device cache coherence property is
propagated through the hierarchy of devices that the VMbus and
Hyper-V virtual PCI drivers set up.

Tested-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>

> ---
> 
> v1 -> v2:
>    * Cover 3 more users of the parent field in struct acpi_device.
>    * Add tags collected so far.
> 
> ---
>  drivers/acpi/acpi_amba.c     |    5 +++--
>  drivers/acpi/acpi_platform.c |    6 +++---
>  drivers/acpi/acpi_video.c    |    2 +-
>  drivers/acpi/device_pm.c     |   19 ++++++++++---------
>  drivers/acpi/property.c      |    6 ++++--
>  drivers/acpi/sbs.c           |    2 +-
>  drivers/acpi/sbshc.c         |    2 +-
>  drivers/acpi/scan.c          |   17 ++++++-----------
>  drivers/hv/vmbus_drv.c       |    3 ++-
>  drivers/perf/arm_dsu_pmu.c   |    4 ++--
>  drivers/perf/qcom_l3_pmu.c   |    3 ++-
>  drivers/spi/spi.c            |    2 +-
>  drivers/thunderbolt/acpi.c   |    2 +-
>  include/acpi/acpi_bus.h      |   10 +++++++++-
>  14 files changed, 46 insertions(+), 37 deletions(-)
> 
> Index: linux-pm/drivers/acpi/scan.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/scan.c
> +++ linux-pm/drivers/acpi/scan.c
> @@ -29,8 +29,6 @@ extern struct acpi_device *acpi_root;
>  #define ACPI_BUS_HID			"LNXSYBUS"
>  #define ACPI_BUS_DEVICE_NAME		"System Bus"
> 
> -#define ACPI_IS_ROOT_DEVICE(device)    (!(device)->parent)
> -
>  #define INVALID_ACPI_HANDLE	((acpi_handle)empty_zero_page)
> 
>  static const char *dummy_hid = "device";
> @@ -1110,7 +1108,7 @@ static void acpi_device_get_busid(struct
>  	 * The device's Bus ID is simply the object name.
>  	 * TBD: Shouldn't this value be unique (within the ACPI namespace)?
>  	 */
> -	if (ACPI_IS_ROOT_DEVICE(device)) {
> +	if (!acpi_dev_parent(device)) {
>  		strcpy(device->pnp.bus_id, "ACPI");
>  		return;
>  	}
> @@ -1646,7 +1644,7 @@ static void acpi_init_coherency(struct a
>  {
>  	unsigned long long cca = 0;
>  	acpi_status status;
> -	struct acpi_device *parent = adev->parent;
> +	struct acpi_device *parent = acpi_dev_parent(adev);
> 
>  	if (parent && parent->flags.cca_seen) {
>  		/*
> @@ -1690,7 +1688,7 @@ static int acpi_check_serial_bus_slave(s
> 
>  static bool acpi_is_indirect_io_slave(struct acpi_device *device)
>  {
> -	struct acpi_device *parent = device->parent;
> +	struct acpi_device *parent = acpi_dev_parent(device);
>  	static const struct acpi_device_id indirect_io_hosts[] = {
>  		{"HISI0191", 0},
>  		{}
> @@ -1767,10 +1765,7 @@ void acpi_init_device_object(struct acpi
>  	INIT_LIST_HEAD(&device->pnp.ids);
>  	device->device_type = type;
>  	device->handle = handle;
> -	if (parent) {
> -		device->parent = parent;
> -		device->dev.parent = &parent->dev;
> -	}
> +	device->dev.parent = parent ? &parent->dev : NULL;
>  	device->dev.release = release;
>  	device->dev.bus = &acpi_bus_type;
>  	fwnode_init(&device->fwnode, &acpi_device_fwnode_ops);
> @@ -1867,8 +1862,8 @@ static int acpi_add_single_object(struct
>  	acpi_device_add_finalize(device);
> 
>  	acpi_handle_debug(handle, "Added as %s, parent %s\n",
> -			  dev_name(&device->dev), device->parent ?
> -				dev_name(&device->parent->dev) : "(null)");
> +			  dev_name(&device->dev), device->dev.parent ?
> +				dev_name(device->dev.parent) : "(null)");
> 
>  	*child = device;
>  	return 0;
> Index: linux-pm/include/acpi/acpi_bus.h
> ===================================================================
> --- linux-pm.orig/include/acpi/acpi_bus.h
> +++ linux-pm/include/acpi/acpi_bus.h
> @@ -365,7 +365,6 @@ struct acpi_device {
>  	int device_type;
>  	acpi_handle handle;		/* no handle for fixed hardware */
>  	struct fwnode_handle fwnode;
> -	struct acpi_device *parent;
>  	struct list_head wakeup_list;
>  	struct list_head del_list;
>  	struct acpi_device_status status;
> @@ -458,6 +457,14 @@ static inline void *acpi_driver_data(str
>  #define to_acpi_device(d)	container_of(d, struct acpi_device, dev)
>  #define to_acpi_driver(d)	container_of(d, struct acpi_driver, drv)
> 
> +static inline struct acpi_device *acpi_dev_parent(struct acpi_device *adev)
> +{
> +	if (adev->dev.parent)
> +		return to_acpi_device(adev->dev.parent);
> +
> +	return NULL;
> +}
> +
>  static inline void acpi_set_device_status(struct acpi_device *adev, u32 sta)
>  {
>  	*((u32 *)&adev->status) = sta;
> @@ -478,6 +485,7 @@ void acpi_initialize_hp_context(struct a
>  /* acpi_device.dev.bus == &acpi_bus_type */
>  extern struct bus_type acpi_bus_type;
> 
> +struct acpi_device *acpi_dev_parent(struct acpi_device *adev);
>  int acpi_bus_for_each_dev(int (*fn)(struct device *, void *), void *data);
>  int acpi_dev_for_each_child(struct acpi_device *adev,
>  			    int (*fn)(struct acpi_device *, void *), void *data);
> Index: linux-pm/drivers/acpi/property.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/property.c
> +++ linux-pm/drivers/acpi/property.c
> @@ -304,8 +304,10 @@ static void acpi_init_of_compatible(stru
>  		ret = acpi_dev_get_property(adev, "compatible",
>  					    ACPI_TYPE_STRING, &of_compatible);
>  		if (ret) {
> -			if (adev->parent
> -			    && adev->parent->flags.of_compatible_ok)
> +			struct acpi_device *parent;
> +
> +			parent = acpi_dev_parent(adev);
> +			if (parent && parent->flags.of_compatible_ok)
>  				goto out;
> 
>  			return;
> Index: linux-pm/drivers/acpi/device_pm.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/device_pm.c
> +++ linux-pm/drivers/acpi/device_pm.c
> @@ -74,6 +74,7 @@ static int acpi_dev_pm_explicit_get(stru
>   */
>  int acpi_device_get_power(struct acpi_device *device, int *state)
>  {
> +	struct acpi_device *parent = acpi_dev_parent(device);
>  	int result = ACPI_STATE_UNKNOWN;
>  	int error;
> 
> @@ -82,8 +83,7 @@ int acpi_device_get_power(struct acpi_de
> 
>  	if (!device->flags.power_manageable) {
>  		/* TBD: Non-recursive algorithm for walking up hierarchy. */
> -		*state = device->parent ?
> -			device->parent->power.state : ACPI_STATE_D0;
> +		*state = parent ? parent->power.state : ACPI_STATE_D0;
>  		goto out;
>  	}
> 
> @@ -122,10 +122,10 @@ int acpi_device_get_power(struct acpi_de
>  	 * point, the fact that the device is in D0 implies that the parent has
>  	 * to be in D0 too, except if ignore_parent is set.
>  	 */
> -	if (!device->power.flags.ignore_parent && device->parent
> -	    && device->parent->power.state == ACPI_STATE_UNKNOWN
> -	    && result == ACPI_STATE_D0)
> -		device->parent->power.state = ACPI_STATE_D0;
> +	if (!device->power.flags.ignore_parent && parent &&
> +	    parent->power.state == ACPI_STATE_UNKNOWN &&
> +	    result == ACPI_STATE_D0)
> +		parent->power.state = ACPI_STATE_D0;
> 
>  	*state = result;
> 
> @@ -159,6 +159,7 @@ static int acpi_dev_pm_explicit_set(stru
>   */
>  int acpi_device_set_power(struct acpi_device *device, int state)
>  {
> +	struct acpi_device *parent = acpi_dev_parent(device);
>  	int target_state = state;
>  	int result = 0;
> 
> @@ -191,12 +192,12 @@ int acpi_device_set_power(struct acpi_de
>  		return -ENODEV;
>  	}
> 
> -	if (!device->power.flags.ignore_parent && device->parent &&
> -	    state < device->parent->power.state) {
> +	if (!device->power.flags.ignore_parent && parent &&
> +	    state < parent->power.state) {
>  		acpi_handle_debug(device->handle,
>  				  "Cannot transition to %s for parent in %s\n",
>  				  acpi_power_state_string(state),
> -				  acpi_power_state_string(device->parent-
> >power.state));
> +				  acpi_power_state_string(parent->power.state));
>  		return -ENODEV;
>  	}
> 
> Index: linux-pm/drivers/acpi/acpi_platform.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/acpi_platform.c
> +++ linux-pm/drivers/acpi/acpi_platform.c
> @@ -78,7 +78,7 @@ static void acpi_platform_fill_resource(
>  	 * If the device has parent we need to take its resources into
>  	 * account as well because this device might consume part of those.
>  	 */
> -	parent = acpi_get_first_physical_node(adev->parent);
> +	parent = acpi_get_first_physical_node(acpi_dev_parent(adev));
>  	if (parent && dev_is_pci(parent))
>  		dest->parent = pci_find_resource(to_pci_dev(parent), dest);
>  }
> @@ -97,6 +97,7 @@ static void acpi_platform_fill_resource(
>  struct platform_device *acpi_create_platform_device(struct acpi_device *adev,
>  						    const struct property_entry
> *properties)
>  {
> +	struct acpi_device *parent = acpi_dev_parent(adev);
>  	struct platform_device *pdev = NULL;
>  	struct platform_device_info pdevinfo;
>  	struct resource_entry *rentry;
> @@ -137,8 +138,7 @@ struct platform_device *acpi_create_plat
>  	 * attached to it, that physical device should be the parent of the
>  	 * platform device we are about to create.
>  	 */
> -	pdevinfo.parent = adev->parent ?
> -		acpi_get_first_physical_node(adev->parent) : NULL;
> +	pdevinfo.parent = parent ? acpi_get_first_physical_node(parent) : NULL;
>  	pdevinfo.name = dev_name(&adev->dev);
>  	pdevinfo.id = -1;
>  	pdevinfo.res = resources;
> Index: linux-pm/drivers/acpi/acpi_video.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/acpi_video.c
> +++ linux-pm/drivers/acpi/acpi_video.c
> @@ -2030,7 +2030,7 @@ static int acpi_video_bus_add(struct acp
>  	acpi_status status;
> 
>  	status = acpi_walk_namespace(ACPI_TYPE_DEVICE,
> -				device->parent->handle, 1,
> +				acpi_dev_parent(device)->handle, 1,
>  				acpi_video_bus_match, NULL,
>  				device, NULL);
>  	if (status == AE_ALREADY_EXISTS) {
> Index: linux-pm/drivers/acpi/sbs.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/sbs.c
> +++ linux-pm/drivers/acpi/sbs.c
> @@ -632,7 +632,7 @@ static int acpi_sbs_add(struct acpi_devi
> 
>  	mutex_init(&sbs->lock);
> 
> -	sbs->hc = acpi_driver_data(device->parent);
> +	sbs->hc = acpi_driver_data(acpi_dev_parent(device));
>  	sbs->device = device;
>  	strcpy(acpi_device_name(device), ACPI_SBS_DEVICE_NAME);
>  	strcpy(acpi_device_class(device), ACPI_SBS_CLASS);
> Index: linux-pm/drivers/acpi/sbshc.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/sbshc.c
> +++ linux-pm/drivers/acpi/sbshc.c
> @@ -266,7 +266,7 @@ static int acpi_smbus_hc_add(struct acpi
>  	mutex_init(&hc->lock);
>  	init_waitqueue_head(&hc->wait);
> 
> -	hc->ec = acpi_driver_data(device->parent);
> +	hc->ec = acpi_driver_data(acpi_dev_parent(device));
>  	hc->offset = (val >> 8) & 0xff;
>  	hc->query_bit = val & 0xff;
>  	device->driver_data = hc;
> Index: linux-pm/drivers/spi/spi.c
> ===================================================================
> --- linux-pm.orig/drivers/spi/spi.c
> +++ linux-pm/drivers/spi/spi.c
> @@ -4375,7 +4375,7 @@ static int acpi_spi_notify(struct notifi
> 
>  	switch (value) {
>  	case ACPI_RECONFIG_DEVICE_ADD:
> -		ctlr = acpi_spi_find_controller_by_adev(adev->parent);
> +		ctlr = acpi_spi_find_controller_by_adev(acpi_dev_parent(adev));
>  		if (!ctlr)
>  			break;
> 
> Index: linux-pm/drivers/thunderbolt/acpi.c
> ===================================================================
> --- linux-pm.orig/drivers/thunderbolt/acpi.c
> +++ linux-pm/drivers/thunderbolt/acpi.c
> @@ -42,7 +42,7 @@ static acpi_status tb_acpi_add_link(acpi
>  	 */
>  	dev = acpi_get_first_physical_node(adev);
>  	while (!dev) {
> -		adev = adev->parent;
> +		adev = acpi_dev_parent(adev);
>  		if (!adev)
>  			break;
>  		dev = acpi_get_first_physical_node(adev);
> Index: linux-pm/drivers/hv/vmbus_drv.c
> ===================================================================
> --- linux-pm.orig/drivers/hv/vmbus_drv.c
> +++ linux-pm/drivers/hv/vmbus_drv.c
> @@ -2427,7 +2427,8 @@ static int vmbus_acpi_add(struct acpi_de
>  	 * Some ancestor of the vmbus acpi device (Gen1 or Gen2
>  	 * firmware) is the VMOD that has the mmio ranges. Get that.
>  	 */
> -	for (ancestor = device->parent; ancestor; ancestor = ancestor->parent) {
> +	for (ancestor = acpi_dev_parent(device); ancestor;
> +	     ancestor = acpi_dev_parent(ancestor)) {
>  		result = acpi_walk_resources(ancestor->handle, METHOD_NAME__CRS,
>  					     vmbus_walk_resources, NULL);
> 
> Index: linux-pm/drivers/acpi/acpi_amba.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/acpi_amba.c
> +++ linux-pm/drivers/acpi/acpi_amba.c
> @@ -48,6 +48,7 @@ static void amba_register_dummy_clk(void
>  static int amba_handler_attach(struct acpi_device *adev,
>  				const struct acpi_device_id *id)
>  {
> +	struct acpi_device *parent = acpi_dev_parent(adev);
>  	struct amba_device *dev;
>  	struct resource_entry *rentry;
>  	struct list_head resource_list;
> @@ -97,8 +98,8 @@ static int amba_handler_attach(struct ac
>  	 * attached to it, that physical device should be the parent of
>  	 * the amba device we are about to create.
>  	 */
> -	if (adev->parent)
> -		dev->dev.parent = acpi_get_first_physical_node(adev->parent);
> +	if (parent)
> +		dev->dev.parent = acpi_get_first_physical_node(parent);
> 
>  	ACPI_COMPANION_SET(&dev->dev, adev);
> 
> Index: linux-pm/drivers/perf/arm_dsu_pmu.c
> ===================================================================
> --- linux-pm.orig/drivers/perf/arm_dsu_pmu.c
> +++ linux-pm/drivers/perf/arm_dsu_pmu.c
> @@ -639,6 +639,7 @@ static int dsu_pmu_dt_get_cpus(struct de
>  static int dsu_pmu_acpi_get_cpus(struct device *dev, cpumask_t *mask)
>  {
>  #ifdef CONFIG_ACPI
> +	struct acpi_device *parent_adev = acpi_dev_parent(ACPI_COMPANION(dev));
>  	int cpu;
> 
>  	/*
> @@ -653,8 +654,7 @@ static int dsu_pmu_acpi_get_cpus(struct
>  			continue;
> 
>  		acpi_dev = ACPI_COMPANION(cpu_dev);
> -		if (acpi_dev &&
> -			acpi_dev->parent == ACPI_COMPANION(dev)->parent)
> +		if (acpi_dev && acpi_dev_parent(acpi_dev) == parent_adev)
>  			cpumask_set_cpu(cpu, mask);
>  	}
>  #endif
> Index: linux-pm/drivers/perf/qcom_l3_pmu.c
> ===================================================================
> --- linux-pm.orig/drivers/perf/qcom_l3_pmu.c
> +++ linux-pm/drivers/perf/qcom_l3_pmu.c
> @@ -742,7 +742,8 @@ static int qcom_l3_cache_pmu_probe(struc
> 
>  	l3pmu = devm_kzalloc(&pdev->dev, sizeof(*l3pmu), GFP_KERNEL);
>  	name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "l3cache_%s_%s",
> -		      acpi_dev->parent->pnp.unique_id, acpi_dev->pnp.unique_id);
> +		      acpi_dev_parent(acpi_dev)->pnp.unique_id,
> +		      acpi_dev->pnp.unique_id);
>  	if (!l3pmu || !name)
>  		return -ENOMEM;
> 
> 
> 





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