Re: [PATCH] bcma: Fix 'allmodconfig' and BCMA builds on MIPS targets

From: Guenter Roeck
Date: Mon Jan 15 2018 - 15:05:56 EST


On 01/15/2018 09:10 AM, Paul Burton wrote:
Hello,

On Mon, Jan 15, 2018 at 10:23:37AM +0000, James Hogan wrote:
On Sun, Jan 14, 2018 at 01:34:02PM -0800, Guenter Roeck wrote:
Mips builds with BCMA host mode enabled fail in mainline and -next
with:

In file included from include/linux/bcma/bcma.h:10:0,
from drivers/bcma/bcma_private.h:9,
from drivers/bcma/main.c:8:
include/linux/bcma/bcma_driver_pci.h:218:24: error:
field 'pci_controller' has incomplete type

Bisect points to commit d41e6858ba58c ("MIPS: Kconfig: Set default MIPS
system type as generic") as the culprit. Analysis shows that the commmit
changes PCI configuration and enables PCI_DRIVERS_GENERIC. This in turn
disables PCI_DRIVERS_LEGACY. 'struct pci_controller' is, however, only
defined if PCI_DRIVERS_LEGACY is enabled.

Ultimately that means that BCMA_DRIVER_PCI_HOSTMODE depends on
PCI_DRIVERS_LEGACY. Add the missing dependency.

Fixes: d41e6858ba58c ("MIPS: Kconfig: Set default MIPS system type as ...")

Well, technically I think commit c5611df96804 ("MIPS: PCI: Introduce
CONFIG_PCI_DRIVERS_LEGACY") is to blame (Cc'ing paul), and the first bad
commit would be commit eed0eabd12ef ("MIPS: generic: Introduce generic
DT-based board support") which selects PCI_DRIVERS_GENERIC and is the
only platform to do so. Both commits were first in v4.9-rc1 and I can
reproduce this problem at that latter commit with the appropriate
configuration.

Ah - yes if I recall correctly my assumption was that the MIPS-specific
struct pci_controller was only used by the MIPS-specific PCI drivers
under arch/mips/pci/, which are only built when configured for the
appropriate platform.

In this case use of that MIPS-specific struct pci_controller has spread
beyond arch/mips/ & the user can be configured in for platforms other
than the one that will actually use the driver, including the generic
platform which moves towards more generic PCI drivers in
drivers/pci/host/.

But yes clearly the mentioned commit does also expose that existing
problem more widely and to the default allmodconfig, and it looks like a
reasonable approach for now, so if some mention of the other two commits
is added:

Reviewed-by: James Hogan <jhogan@xxxxxxxxxx>

Likewise, with the "Fixes:" tag fixed:

Reviewed-by: Paul Burton <paul.burton@xxxxxxxx>


Unfortunately, that alone doesn't fix the problem. SSB driver dependencies
are also broken, and in much worse shape. I had to add dependencies in five
places to get it to build, and the result is so messy that I won't even try
to submit it. And if that is fixed, mips:allmodconfig still doesn't build -
the next error is an undefined reference to physical_memsize in
arch/mips/kernel/vpe-mt.o.

I wonder if I should just stop trying to build allmodconfig for mips.
Any thoughts ?

Guenter

Thanks,
Paul

Having it in 4.15 would be great.

Cheers
James

Cc: Matt Redfearn <matt.redfearn@xxxxxxxxxx>
Cc: James Hogan <jhogan@xxxxxxxxxx>
Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
---
I am aware that this problem has been reported several times. I have
not been able to find a fix, but I may have missed it. If so, my
apologies for the noise.

Also note that this is not the only fix required; commit d41e6858ba58c,
as simple as it looks like, does a pretty good job messing up
"mips:allmodconfig" builds.

drivers/bcma/Kconfig | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/bcma/Kconfig b/drivers/bcma/Kconfig
index 02d78f6cecbb..ba8acca036df 100644
--- a/drivers/bcma/Kconfig
+++ b/drivers/bcma/Kconfig
@@ -55,7 +55,7 @@ config BCMA_DRIVER_PCI
config BCMA_DRIVER_PCI_HOSTMODE
bool "Driver for PCI core working in hostmode"
- depends on MIPS && BCMA_DRIVER_PCI
+ depends on MIPS && BCMA_DRIVER_PCI && PCI_DRIVERS_LEGACY
help
PCI core hostmode operation (external PCI bus).
--
2.7.4