From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Zhang Rui <rui.zhang@intel.com>
Cc: linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org,
        bhelgaas@google.com, matthew.garrett@nebula.com,
        rafael.j.wysocki@intel.com, dmitry.torokhov@gmail.com
Subject: Re: [PATCH V5 12/12] ACPI: introduce .handle_children flag for acpi scan handler
Date: Mon, 28 Apr 2014 00:26:12 +0200
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On Tuesday, April 08, 2014 12:06:59 AM Zhang Rui wrote:
> For some devices with scan handler attached, their children devices
> are enumerated by the scan handler, indirectly.

This isn't the case really.  They are enumerated by bus controller drivers
for the buses they are on.

> In this case, we do not want to enumerate the children devices in
> acpi scan code explicitly.
> 
> Thus a new flag .handle_children is introduced in this patch.
> 
> For scan handlers with this flag set, we will do default enumeration neither
> for the attached devices nor for the children of the attached devices.

I'm not sure if that is the right approach.  I would prefer that to be
handled in a more fine-graind manner, like a flag per device ID or something
similar?

> Signed-off-by: Zhang Rui <rui.zhang@intel.com>
> ---
>  drivers/acpi/acpi_lpss.c |    2 ++
>  drivers/acpi/scan.c      |   28 ++++++++++++++++++++++++++--
>  include/acpi/acpi_bus.h  |    4 +++-
>  3 files changed, 31 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/acpi/acpi_lpss.c b/drivers/acpi/acpi_lpss.c
> index 965428f..da0a3d4 100644
> --- a/drivers/acpi/acpi_lpss.c
> +++ b/drivers/acpi/acpi_lpss.c
> @@ -521,6 +521,7 @@ static struct acpi_scan_handler lpss_handler = {
>  	.attach = acpi_lpss_create_device,
>  	.bind = acpi_lpss_bind,
>  	.unbind = acpi_lpss_unbind,
> +	.handle_children = true,
>  };
>  
>  #endif /* CONFIG_X86_INTEL_LPSS */
> @@ -534,6 +535,7 @@ static int acpi_lpss_dummy_attach(struct acpi_device *adev,
>  static struct acpi_scan_handler lpss_dummy_handler = {
>  	.ids = acpi_lpss_device_ids,
>  	.attach = acpi_lpss_dummy_attach,
> +	.handle_children = true,
>  };
>  
>  void __init acpi_lpss_init(void)
> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> index 44c4668..4ea867e 100644
> --- a/drivers/acpi/scan.c
> +++ b/drivers/acpi/scan.c
> @@ -2073,6 +2073,31 @@ static acpi_status acpi_bus_check_add(acpi_handle handle, u32 lvl_not_used,
>  	return AE_OK;
>  }
>  
> +static void acpi_do_default_enumeration(struct acpi_device *device)
> +{
> +	/*
> +	 * Do not do enumeration for device object that
> +	 * its parent doesn't want to
> +	 */
> +	if (device->parent && device->parent->flags.no_child_enumeration) {
> +		device->flags.no_child_enumeration = 1;
> +		return;
> +	}
> +
> +	/* Do not do enumeration for device object with scan handler attached */
> +	if (device->handler) {
> +		if (device->handler->handle_children)
> +			device->flags.no_child_enumeration = 1;
> +		return;
> +	}
> +
> +	/* Do not do enumeration for device object w/o platform_id */
> +	if (!device->pnp.type.platform_id)
> +		return;
> +
> +	acpi_create_platform_device(device, NULL);
> +}
> +
>  static int acpi_scan_attach_handler(struct acpi_device *device)
>  {
>  	struct acpi_hardware_id *hwid;
> @@ -2095,8 +2120,7 @@ static int acpi_scan_attach_handler(struct acpi_device *device)
>  		}
>  	}
>  
> -	if (device->pnp.type.platform_id && !device->handler)
> -		acpi_create_platform_device(device, NULL);
> +	acpi_do_default_enumeration(device);
>  
>  	return ret;
>  }
> diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
> index ec92ad3..4724fe5 100644
> --- a/include/acpi/acpi_bus.h
> +++ b/include/acpi/acpi_bus.h
> @@ -137,6 +137,7 @@ struct acpi_scan_handler {
>  	void (*bind)(struct device *phys_dev);
>  	void (*unbind)(struct device *phys_dev);
>  	struct acpi_hotplug_profile hotplug;
> +	bool handle_children;
>  };
>  
>  /*
> @@ -207,7 +208,8 @@ struct acpi_device_flags {
>  	u32 no_hotplug:1;
>  	u32 hotplug_notify:1;
>  	u32 is_dock_station:1;
> -	u32 reserved:22;
> +	u32 no_child_enumeration:1;
> +	u32 reserved:21;
>  };
>  
>  /* File System */
> 

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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