linux-kernel - Re: [PATCH V5 12/12] ACPI: introduce .handle

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Date:	Mon, 28 Apr 2014 10:07:50 +0800
From:	Zhang Rui <rui.zhang@...el.com>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:	linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
	bhelgaas@...gle.com, matthew.garrett@...ula.com,
	rafael.j.wysocki@...el.com, dmitry.torokhov@...il.com
Subject: Re: [PATCH V5 12/12] ACPI: introduce .handle_children flag for acpi
 scan handler

On Mon, 2014-04-28 at 00:26 +0200, Rafael J. Wysocki wrote:
> 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.
> 
that's what I mean by saying "indirectly". :)

> > 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?
> 
hmmm, how about this,
first, keep the device->flags.no_child_enumeration flag introduced in
this patch
second, set the flag explicitly, for specified devices, in the scan
handler .attach() function.

thanks,
rui
> > Signed-off-by: Zhang Rui <rui.zhang@...el.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 */
> > 
> 


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