Re: [PATCH] drm/fb: Fix randconfig builds

[Jani Nikula <jani.nikula@linux.intel.com>]

On Mon, 16 Aug 2021, Jani Nikula <jani.nikula@linux.intel.com> wrote:
> On Mon, 16 Aug 2021, Jackie Liu <liu.yun@linux.dev> wrote:
>> Hi Jani.
>>
>> Your suggestion is that?
>>
>> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
>> index 7ff89690a976..ba179a539497 100644
>> --- a/drivers/gpu/drm/Kconfig
>> +++ b/drivers/gpu/drm/Kconfig
>> @@ -77,6 +77,7 @@ config DRM_DEBUG_SELFTEST
>>   config DRM_KMS_HELPER
>>          tristate
>>          depends on DRM
>> +       depends on FB if DRM_FBDEV_EMULATION
>>          help
>>            CRTC helpers for KMS drivers.
>>
>>
>> But it has a syntax error.
>
> Ah, try this then:
>
> 	depends on FB || FB=n

Or this monster:

	depends on FB || DRM_FBDEV_EMULATION=n


>
>>
>> --
>> Thanks, BR, Jackie Liu
>>
>> 在 2021/8/16 下午4:33, Jani Nikula 写道:
>>> On Mon, 16 Aug 2021, Jackie Liu <liu.yun@linux.dev> wrote:
>>>> Hi Jani.
>>>>
>>>> My CI report an randconfigs build failed. there are:
>>>>
>>>> drm_fb_helper.c:(.text+0x302): undefined reference to `fb_set_suspend'
>>>> drm_fb_helper.c:(.text+0xaea): undefined reference to `register_framebuffer'
>>>> drm_fb_helper.c:(.text+0x1dcc): undefined reference to `framebuffer_alloc'
>>>> ld: drm_fb_helper.c:(.text+0x1dea): undefined reference to `fb_alloc_cmap'
>>>> ld: drm_fb_helper.c:(.text+0x1e2f): undefined reference to `fb_dealloc_cmap'
>>>> ld: drm_fb_helper.c:(.text+0x1e5b): undefined reference to
>>>> `framebuffer_release'
>>>> drm_fb_helper.c:(.text+0x1e85): undefined reference to
>>>> `unregister_framebuffer'
>>>> drm_fb_helper.c:(.text+0x1ee9): undefined reference to `fb_dealloc_cmap'
>>>> ld: drm_fb_helper.c:(.text+0x1ef0): undefined reference to
>>>> `framebuffer_release'
>>>> drm_fb_helper.c:(.text+0x1f96): undefined reference to
>>>> `fb_deferred_io_cleanup'
>>>> drm_fb_helper.c:(.text+0x203b): undefined reference to `fb_sys_read'
>>>> drm_fb_helper.c:(.text+0x2051): undefined reference to `fb_sys_write'
>>>> drm_fb_helper.c:(.text+0x208d): undefined reference to `sys_fillrect'
>>>> drm_fb_helper.c:(.text+0x20bb): undefined reference to `sys_copyarea'
>>>> drm_fb_helper.c:(.text+0x20e9): undefined reference to `sys_imageblit'
>>>> drm_fb_helper.c:(.text+0x2117): undefined reference to `cfb_fillrect'
>>>> drm_fb_helper.c:(.text+0x2172): undefined reference to `cfb_copyarea'
>>>> drm_fb_helper.c:(.text+0x21cd): undefined reference to `cfb_imageblit'
>>>> drm_fb_helper.c:(.text+0x2233): undefined reference to `fb_set_suspend'
>>>> drm_fb_helper.c:(.text+0x22b0): undefined reference to `fb_set_suspend'
>>>> drm_fb_helper.c:(.text+0x250f): undefined reference to `fb_deferred_io_init'
>>>>
>>>> The main reason is because DRM_FBDEV_EMULATION is built-in, and
>>>> CONFIG_FB is compiled as a module.
>>> 
>>> DRM_FBDEV_EMULATION is not a module, it's just a config
>>> knob. drm_fb_helper.ko is the module, enabled via DRM_KMS_HELPER, and it
>>> has an implicit dependency on FB, and DRM_FBDEV_EMULATION selects
>>> DRM_KMS_HELPER. Select just breaks dependencies in all kinds of ways.
>>> 
>>> This might help in config DRM_KMS_HELPER, and it might help the reader
>>> because it's factual:
>>> 
>>> 	depends on FB if DRM_FBDEV_EMULATION
>>> 
>>> 
>>> BR,
>>> Jani.
>>> 
>>> 
>>> 
>>> 
>>> 
>>>>
>>>> --
>>>> Jackie Liu
>>>>
>>>> 在 2021/8/16 下午3:01, Jani Nikula 写道:
>>>>> On Mon, 16 Aug 2021, Jackie Liu <liu.yun@linux.dev> wrote:
>>>>>> From: Jackie Liu <liuyun01@kylinos.cn>
>>>>>>
>>>>>> When CONFIG_DRM_FBDEV_EMULATION is compiled to y and CONFIG_FB is m, the
>>>>>> compilation will fail. we need make that dependency explicit.
>>>>>
>>>>> What's the failure mode? Using select here is a bad idea.
>>>>>
>>>>> BR,
>>>>> Jani.
>>>>>
>>>>>>
>>>>>> Reported-by: k2ci <kernel-bot@kylinos.cn>
>>>>>> Signed-off-by: Jackie Liu <liuyun01@kylinos.cn>
>>>>>> ---
>>>>>>    drivers/gpu/drm/Kconfig | 2 +-
>>>>>>    1 file changed, 1 insertion(+), 1 deletion(-)
>>>>>>
>>>>>> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
>>>>>> index 7ff89690a976..346a518b5119 100644
>>>>>> --- a/drivers/gpu/drm/Kconfig
>>>>>> +++ b/drivers/gpu/drm/Kconfig
>>>>>> @@ -98,7 +98,7 @@ config DRM_DEBUG_DP_MST_TOPOLOGY_REFS
>>>>>>    config DRM_FBDEV_EMULATION
>>>>>>    	bool "Enable legacy fbdev support for your modesetting driver"
>>>>>>    	depends on DRM
>>>>>> -	depends on FB
>>>>>> +	select FB
>>>>>>    	select DRM_KMS_HELPER
>>>>>>    	select FB_CFB_FILLRECT
>>>>>>    	select FB_CFB_COPYAREA
>>>>>
>>> 

-- 
Jani Nikula, Intel Open Source Graphics Center