On Mon, Jan 25, 2021 at 5:22 PM Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote:
>
> On Mon, Jan 25, 2021 at 12:32:30PM +0100, Arnd Bergmann wrote:
> > From: Arnd Bergmann <arnd@xxxxxxxx>
> >
> > Selecting the chipidea driver from the old Kconfig symbol
> > can lead to a missing dependency:
>
> Arnd:
>
> I found this whole patch a little confusing. For example, in the
> sentence above, what does "the old Kconfig symbol" refer to?
>
> Comparing the various Kconfig files, I see what the problem is. The
> commit which this one fixes made CONFIG_EHCI_TEGRA select
> CONFIG_USB_CHIPIDEA, but it didn't make EHCI_TEGRA depend on the things
> that USB_CHIPIDEA depends on. Can you please state this more explicitly
> in the patch description?
Sure, I'll resend in a bit.
> > WARNING: unmet direct dependencies detected for USB_CHIPIDEA
> > Depends on [m]: USB_SUPPORT [=y] && (USB_EHCI_HCD [=y] && USB_GADGET [=m] || USB_EHCI_HCD [=y] && !USB_GADGET [=m] || !USB_EHCI_HCD [=y] && USB_GADGET [=m]) && HAS_DMA [=y]
> > Selected by [y]:
> > - USB_EHCI_TEGRA [=y] && USB_SUPPORT [=y] && USB [=y] && USB_EHCI_HCD [=y] && ARCH_TEGRA [=y]
> > aarch64-linux-ld: drivers/usb/chipidea/otg.o: in function `ci_handle_vbus_change':
> > otg.c:(.text+0x3c8): undefined reference to `usb_gadget_vbus_connect'
> > aarch64-linux-ld: otg.c:(.text+0x42c): undefined reference to `usb_gadget_vbus_disconnect'
> > aarch64-linux-ld: drivers/usb/chipidea/otg.o: in function `ci_otg_work':
> > otg.c:(.text+0x5d4): undefined reference to `usb_gadget_vbus_disconnect'
> > ...
> >
> > Duplicate the dependency to ensure that this driver can
> > only be a loadable module if one of its dependencies is.
> >
> > Fixes: c3590c7656fb ("usb: host: ehci-tegra: Remove the driver")
> > Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> > ---
> > drivers/usb/host/Kconfig | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/drivers/usb/host/Kconfig b/drivers/usb/host/Kconfig
> > index 160e5d3927e2..66b01b619ecd 100644
> > --- a/drivers/usb/host/Kconfig
> > +++ b/drivers/usb/host/Kconfig
> > @@ -269,6 +269,7 @@ config USB_EHCI_HCD_AT91
> > config USB_EHCI_TEGRA
> > tristate "NVIDIA Tegra HCD support"
> > depends on ARCH_TEGRA
> > + depends on ((USB_EHCI_HCD && USB_GADGET) || (USB_EHCI_HCD && !USB_GADGET) || (!USB_EHCI_HCD && USB_GADGET)) && HAS_DMA
> > select USB_CHIPIDEA
> > select USB_CHIPIDEA_HOST
> > select USB_CHIPIDEA_TEGRA
>
> Isn't there at least one other missing dependency? This entry selects
> USB_CHIPIDEA_TEGRA, which depends on OF. So shouldn't this entry also
> depend on OF? Or does the Kconfig system detect that for us?
Yes, there is a hard dependency on ARCH_TEGRA, which implies OF.
> Also, while I'm no expert on the Kconfig language, it seems that the new
> "depends" line could be a lot easier to understand if it was refactored
> with some comments added. Yes, I realize you just copied the existing
> dependency from the USB_CHIPIDEA entry -- that one could stand to be
> cleaned up as well.
>
> For instance, how about putting the HAS_DMA part into a separate line,
> since it's unrelated to the other stuff?
Actually it's probably best to just drop the HAS_DMA here, as it is also
implied by ARCH_TEGRA.
> And the rest looks like it
> could be changed to:
>
> depends on USB_EHCI_HCD || USB_GADGET
>
> although that probably isn't quite valid. Still, can't it be changed to
> something simpler than
>
> (USB_EHCI_HCD && USB_GADGET) || (USB_EHCI_HCD && !USB_GADGET) ||
> (!USB_EHCI_HCD && USB_GADGET)
The problem is that if either USB_EHCI_HCD or USB_GADGET are loadable
modules, then USB_CHIPIDEA must not be built-in, but if one of the two is
disabled, we must still have a dependency on the other. I guess it could be
rewritten into
depends on USB_EHCI_HCD || USB_GADGET # needs at least one of the two
depends on m || USB_EHCI_HCD!=m # must be =m if USB_EHCI_HCD=m
depends on m || USB_GADGET!=m # must be =m if USB_GADGET=m
I see that USB_EHCI_TEGRA already depends on USB_EHCI_HCD,
so I think this collapses into a much simpler
depends on USB_GADGET || USB_GADGET=n # for USB_CHIPIDEA
Arnd
