Re: [PATCH 00/10] usb: phy: cleanups to Kconfig and directories

[Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>]

On 03/08/2013 04:08 PM, Arnd Bergmann wrote:
> On Friday 08 March 2013, Stephen Warren wrote:
>> Yes, I think it should instead work like:
>>
>> ARCH_TEGRA* selects nothing in particular related to USB.
>>
>> The Tegra EHCI controller Kconfig depends on ARCH_TEGRA so it doesn't
>> show up for other builds.
> 
> Yes, that's fine.
> 
>> I hope it's OK for the EHCI controller to select USB_ARCH_HAS_EHCI?
> 
> I think that would create a circular dependency, which Kconfig will
> refuse. We talked about the USB_ARCH_HAS_* Kconfig symbols recently
> and Alan Stern agreed to my suggestion of removing all of them,
> reworking the logic so we can always enable USB and EHCI but even
> when there is no bus glue enabled.
> 
> I'll have to do a proper patch one of these days, or find someone in
> my team to do it right for all the corner cases.
> 
>> The Tegra PHY Kconfig probably shouldn't be user-visible (relying on
>> being selected by the Tegra EHCI controller) and itself selects
>> anything it relies on.
>>
>> Does that sound reasonable?
> 
> It is often safer to express the logic using "depends on" than using
> "select", e.g. doing
> 
> config USB_EHCI_TEGRA
> 	bool "EHCI support for NVIDIA Tegra"
> 	depends on USB_EHCI_HCD
> 	depends on ARCH_TEGRA
> 
> config USB_ULPI_VIEWPORT
> 	def_bool y
> 	depends on USB_EHCI_TEGRA
> 
> If USB_ULPI_VIEWPORT has any other dependencies, the best solution
> in the above scenario is to make USB_EHCI_TEGRA depend on those.

USB_ULPI_VIEWPORT is, AFAIK, a generic piece of infra-structure that
USB_EHCI_TEGRA depends upon.