Subject: Re: USB-related build errors on Tegra in next-20130319

From: Stephen Warren <[email-masked]>
Date: Wed, 20 Mar 2013 10:39:11 -0600

On 03/20/2013 06:20 AM, Felipe Balbi wrote:
> Hi,
> 
> On Tue, Mar 19, 2013 at 10:29:05AM -0600, Stephen Warren wrote:
>> I see the following Kconfig warnings in next-20130319:
>> 
>>> warning: (ARCH_TEGRA_2x_SOC && ARCH_TEGRA_3x_SOC) selects
>>> USB_ULPI which has unmet direct dependencies (USB_SUPPORT &&
>>> USB_PHY && ARM) warning: (ARCH_TEGRA_2x_SOC &&
>>> ARCH_TEGRA_3x_SOC) selects USB_ULPI_VIEWPORT which has unmet
>>> direct dependencies (USB_SUPPORT && USB_PHY && USB_ULPI) 
>>> include/config/auto.conf:624:warning: override:
>>> ARCH_MULTIPLATFORM changes choice state warning:
>>> (ARCH_TEGRA_2x_SOC && ARCH_TEGRA_3x_SOC) selects USB_ULPI which
>>> has unmet direct dependencies (USB_SUPPORT && USB_PHY && ARM) 
>>> warning: (ARCH_TEGRA_2x_SOC && ARCH_TEGRA_3x_SOC) selects
>>> USB_ULPI_VIEWPORT which has unmet direct dependencies
>>> (USB_SUPPORT && USB_PHY && USB_ULPI)
>> 
>> Which I believe are the cause of the following build errors:
>> 
>>> drivers/built-in.o: In function `controller_resume': 
>>> drivers/usb/host/ehci-tegra.c:556: undefined reference to
>>> `tegra_usb_phy_preresume' drivers/usb/host/ehci-tegra.c:479:
>>> undefined reference to `tegra_ehci_phy_restore_start' 
>>> drivers/usb/host/ehci-tegra.c:551: undefined reference to
>>> `tegra_ehci_phy_restore_end' drivers/usb/host/ehci-tegra.c:546:
>>> undefined reference to `tegra_ehci_phy_restore_end' 
>>> drivers/built-in.o: In function `tegra_ehci_probe': 
>>> drivers/usb/host/ehci-tegra.c:734: undefined reference to
>>> `tegra_usb_phy_open' drivers/built-in.o: In function
>>> `tegra_ehci_hub_control': drivers/usb/host/ehci-tegra.c:162:
>>> undefined reference to `tegra_usb_phy_postresume' 
>>> drivers/usb/host/ehci-tegra.c:215: undefined reference to
>>> `tegra_usb_phy_preresume' make: *** [vmlinux] Error 1
>> 
>> I pointed out at least the Kconfig problems when you posted the
>> PHY error handling cleanup series, so I'm not sure why those
>> patches were applied.
> 
> Because tegra EHCI shouldn't be selecting the PHY and you didn't
> even have a proper PHY driver. Try patch below:

I understand that, but applying the patches without that resolved
still seems wrong. Just because something is currently sub-optimal
doesn't mean it should get broken.

The patch you gave fixes the Kconfig warnings, but not the build failure.

The issue is that: tegra_defconfig enables CONFIG_USB_EHCI_TEGRA, but
not CONFIG_USB_PHY since it's new. ehci-tegra.c directly calls
functions exported by phy-tegra-usb.c. However, phy-tegra-usb.c
doesn't get built, since drivers/usb/Makefile adds phy/ to
obj-$(CONFIG_USB_PHY), so doesn't end up "recursing" into the
sub-directory at all. drivers/usb/phy/Makefile contains:
obj-$(CONFIG_USB_EHCI_TEGRA)+= phy-tegra-usb.o which used to couple
the two builds together, in the absence of this new change that limits
the building of phy/.

For now, I think the correct solution is to have USB_EHCI_TEGRA select
USB_PHY. I validated that solves the build problem, and has the bonus
of not needing any changes to tegra_defconfig.

In the series that converts phy-usb-tegra.c to a real driver, we can
give it its own Kconfig option, and have USB_EHCI_TEGRA depend on
that, if you want. We'll then also need to take a patch through the
Tegra tree to update tegra_defconfig.
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