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

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Date:   Mon, 15 Jan 2018 12:05:48 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Paul Burton <paul.burton@...s.com>, James Hogan <jhogan@...nel.org>
Cc:     Rafał Miłecki <zajec5@...il.com>,
        linux-wireless@...r.kernel.org, linux-kernel@...r.kernel.org,
        Matt Redfearn <matt.redfearn@...tec.com>,
        Linux MIPS Mailing List <linux-mips@...ux-mips.org>
Subject: Re: [PATCH] bcma: Fix 'allmodconfig' and BCMA builds on MIPS targets

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@...nel.org>
> 
> Likewise, with the "Fixes:" tag fixed:
> 
>      Reviewed-by: Paul Burton <paul.burton@...s.com>
> 

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@...tec.com>
>>> Cc: James Hogan <jhogan@...nel.org>
>>> Signed-off-by: Guenter Roeck <linux@...ck-us.net>
>>> ---
>>> 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
>>>
> 
> 
>