linux-kernel - Re: [PATCH, RFC 2/2] USB: host: make USB_ARCH_HAS

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Message-ID: <1624672.VBbVgzJXAH@wuerfel>
Date:	Tue, 04 Jun 2013 17:38:45 +0200
From:	Arnd Bergmann <arnd@...db.de>
To:	Alan Stern <stern@...land.harvard.edu>
Cc:	linux-usb@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH, RFC 2/2] USB: host: make USB_ARCH_HAS_?HCI obsolete

On Tuesday 04 June 2013 11:22:01 Alan Stern wrote:
> 
> Instead of doing this, it makes more sense to enable USB_ARCH_HAS_HCD
> whenever host-side USB is enabled.  In other words,
> 
>         def_bool USB

The problem with this is that a lot of drivers (24 to be exact) are defined
like

config INPUT_ATI_REMOTE2
        tristate "ATI / Philips USB RF remote control"
        depends on USB_ARCH_HAS_HCD
        select USB

so that would create a circular dependency unless we change all of them
at once. I did that when creating this patch, but then decided to
revert it for now and do smaller steps.

We could do

config USB_ARCH_HAS_HCD
	def_bool USB_SUPPORT

or

config USB_ARCH_HAS_HCD
	def_bool y

which would both have the exact same behavior as 'def_bool HAS_IOMEM'.
 
> The HAS_IOMEM won't matter, because USB is defined only when 
> USB_SUPPORT is enabled, and USB_SUPPORT already depends on HAS_IOMEM.

Right.

> Of course, it will then be necessary to remove the dependency on 
> USB_ARCH_HAS_HCD from the "config USB" entry.  Which is exactly what 
> you're trying to accomplish, anyway.

That dependency is redundant already, and should certainly be
removed now.

> > diff --git a/drivers/usb/host/Kconfig b/drivers/usb/host/Kconfig
> > index e060ecf..045f9d27 100644
> > --- a/drivers/usb/host/Kconfig
> > +++ b/drivers/usb/host/Kconfig
> > @@ -17,7 +17,7 @@ config USB_C67X00_HCD
> >  
> >  config USB_XHCI_HCD
> >       tristate "xHCI HCD (USB 3.0) support"
> > -     depends on USB_ARCH_HAS_XHCI
> > +     depends on PCI
> 
> You probably don't want to add this dependency.  After all, one of the
> comments removed above points out that there are non-PCI xHCI
> controllers.

Yes, that was a mistake. I noticed this myself but forgot to edit
the file again.

	Arnd
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