linux-kernel - Re: build failure in linux-next: offb missing fb helpers

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Date:   Sun, 20 Nov 2022 18:47:08 +0100
From:   Thomas Zimmermann <tzimmermann@...e.de>
To:     Randy Dunlap <rdunlap@...radead.org>,
        Michal Suchánek <msuchanek@...e.de>,
        Masahiro Yamada <masahiroy@...nel.org>
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-fbdev@...r.kernel.org, linux-kbuild@...r.kernel.org
Subject: Re: build failure in linux-next: offb missing fb helpers

Hi

Am 19.11.22 um 19:15 schrieb Randy Dunlap:
> Hi,
> 
> On 11/19/22 07:37, Michal Suchánek wrote:
>> Hello,
>>
>> On Sat, Nov 19, 2022 at 10:27:04PM +0900, Masahiro Yamada wrote:
>>> On Sat, Nov 19, 2022 at 3:20 PM Randy Dunlap <rdunlap@...radead.org> wrote:
>>>>
>>>> Hi--
>>>>
>>>> [adding Masahiro-san]
>>>>
>>>>
>>>> On 11/18/22 07:03, Michal Suchánek wrote:
>>>>> Hello,
>>>>>
>>>>> I am seeing these errors:
>>>>>
>>>>> [ 3825s]   AR      built-in.a
>>>>> [ 3827s]   AR      vmlinux.a
>>>>> [ 3835s]   LD      vmlinux.o
>>>>> [ 3835s]   OBJCOPY modules.builtin.modinfo
>>>>> [ 3835s]   GEN     modules.builtin
>>>>> [ 3835s]   GEN     .vmlinux.objs
>>>>> [ 3848s]   MODPOST Module.symvers
>>>>> [ 3848s]   CC      .vmlinux.export.o
>>>>> [ 3849s]   UPD     include/generated/utsversion.h
>>>>> [ 3849s]   CC      init/version-timestamp.o
>>>>> [ 3849s]   LD      .tmp_vmlinux.btf
>>>>> [ 3864s] ld: drivers/video/fbdev/offb.o:(.data.rel.ro+0x58): undefined
>>>>> reference to `cfb_fillrect'
>>>>> [ 3864s] ld: drivers/video/fbdev/offb.o:(.data.rel.ro+0x60): undefined
>>>>> reference to `cfb_copyarea'
>>>>> [ 3864s] ld: drivers/video/fbdev/offb.o:(.data.rel.ro+0x68): undefined
>>>>> reference to `cfb_imageblit'
>>>>>
>>>>> cfb_fillrect is provided by drivers/video/fbdev/core/cfbfillrect.c
>>>>>
>>>>> It is compiled when CONFIG_FB_CFB_FILLRECT
>>>>> drivers/video/fbdev/core/Makefile:obj-$(CONFIG_FB_CFB_FILLRECT)  += cfbfillrect.o
>>>>>
>>>>> drivers/video/fbdev/Makefile:obj-$(CONFIG_FB_OF)               += offb.o
>>>>> is compiled when CONFIG_FB_OF
>>>>>
>>>>> It selects CONFIG_FB_CFB_FILLRECT
>>>>> config FB_OF
>>>>>          bool "Open Firmware frame buffer device support"
>>>>>          depends on (FB = y) && PPC && (!PPC_PSERIES || PCI)
>>>>>          select APERTURE_HELPERS
>>>>>          select FB_CFB_FILLRECT
>>>>>          select FB_CFB_COPYAREA
>>>>>          select FB_CFB_IMAGEBLIT
>>>>>          select FB_MACMODES
>>>>>
>>>>> The config has FB_OF built-in and FB_CFB_FILLRECT modular
>>>>> config/ppc64le/vanilla:CONFIG_FB_CFB_FILLRECT=m
>>>>> config/ppc64le/vanilla:CONFIG_FB_CFB_COPYAREA=m
>>>>> config/ppc64le/vanilla:CONFIG_FB_CFB_IMAGEBLIT=m
>>>>> config/ppc64le/vanilla:CONFIG_FB_OF=y
>>>>>
>>>>> It only depends on FB which mut be built-in for FB_OF
>>>>> config FB_CFB_FILLRECT
>>>>>          tristate
>>>>>          depends on FB
>>>>>
>>>>> Is select in kconfig broken?
>>>>>
>>>>> Attachnig the config in question.
>>>>
>>>> The symbol info from xconfig says:
>>>>
>>>> Symbol: FB_CFB_FILLRECT [=m]
>>>> Type : tristate
>>>> Defined at drivers/video/fbdev/Kconfig:69
>>>> Depends on: HAS_IOMEM [=y] && FB [=y]
>>>> Selected by [m]:
>>>> [deleted]
>>>> - FB_OF [=y] && HAS_IOMEM [=y] && FB [=y]=y && PPC [=y] && (!PPC_PSERIES [=y] || PCI [=y]) && !DRM_OFDRM [=m]
>>>>
>>>> I don't see why the 'select' from (bool) FB_OF would leave FB_CFB_FILLRECT (and the others)
>>>> as =m instead of =y.
>>>>
>>>> Hopefully Masahiro can shed some light on this.
>>>>
>>>> --
>>>> ~Randy
>>>
>>>
>>> The reason is shown in your paste of help message:
>>>
>>> "&& !DRM_OFDRM [=m]" downgrades it to "selected by m"
>>>
>>> To aid this particular case, the following will select
>>> FB_CFB_FILLRECT=y.
>>>
>>>
> 
> Thanks again for your help.
> 
>>>
>>>
>>> diff --git a/drivers/video/fbdev/Kconfig b/drivers/video/fbdev/Kconfig
>>> index 66f36b69e8f3..2bcf8627819f 100644
>>> --- a/drivers/video/fbdev/Kconfig
>>> +++ b/drivers/video/fbdev/Kconfig
>>> @@ -458,7 +458,7 @@ config FB_ATARI
>>>   config FB_OF
>>>          bool "Open Firmware frame buffer device support"
>>>          depends on (FB = y) && PPC && (!PPC_PSERIES || PCI)
>>> -       depends on !DRM_OFDRM
>>> +       depends on DRM_OFDRM != y
>>>          select APERTURE_HELPERS
>>>          select FB_CFB_FILLRECT
>>>          select FB_CFB_COPYAREA
>>
>> Thanks for clarification.
>>
>> This change fixess the config for me.
> 
> 
> Thomas, is this change to DRM_OFDRM under FB_OF acceptable to you?

Sure, thanks for helping.

The only reason for adding this Kconfig rule is that it doesn't make 
much sense to have offb and ofdrm enabled at the same time. BTW we have 
a similar rule for simplefb/simpledrm, which never made any problems.

Best regards
Thomas

> 
> 
>>> Or, perhaps "depends on DRM_OFDRM = n"
>>> I do not know the intention of this dependency.
>>>
>>> Recommendation is to use "depends on" instead of "select" though.
>>>
>>>
>>>
>>> BTW, this is similar to what you asked before.
>>>
>>> https://lore.kernel.org/linux-kbuild/e1a6228d-1341-6264-d97a-e2bd52a65c82@infradead.org/
>>>
>>>
>>> I tried to fix it in the past, but the issue was not as shallow as I
>>> had expected.
>>> I did not get around to revisiting this topic.
>>>
>>> https://patchwork.kernel.org/project/linux-kbuild/patch/1543216969-2227-1-git-send-email-yamada.masahiro@socionext.com/
>>>
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev

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