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

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

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

>
> --
> 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