linux-kernel - Re: [PATCH -next] fbdev: offb: allow build when DRM

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Date:   Wed, 23 Nov 2022 09:02:54 +0100
From:   Thomas Zimmermann <tzimmermann@...e.de>
To:     Randy Dunlap <rdunlap@...radead.org>, linux-kernel@...r.kernel.org
Cc:     Masahiro Yamada <masahiroy@...nel.org>,
        Michal Suchánek <msuchanek@...e.de>,
        linuxppc-dev@...ts.ozlabs.org, Daniel Vetter <daniel@...ll.ch>,
        Helge Deller <deller@....de>, linux-fbdev@...r.kernel.org,
        dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH -next] fbdev: offb: allow build when DRM_OFDRM=m


Am 23.11.22 um 04:16 schrieb Randy Dunlap:
> Fix build when CONFIG_FB_OF=y and CONFIG_DRM_OFDRM=m.
> When the latter symbol is =m, kconfig downgrades (limits) the 'select's
> under FB_OF to modular (=m). This causes undefined symbol references:
> 
> powerpc64-linux-ld: drivers/video/fbdev/offb.o:(.data.rel.ro+0x58): undefined reference to `cfb_fillrect'
> powerpc64-linux-ld: drivers/video/fbdev/offb.o:(.data.rel.ro+0x60): undefined reference to `cfb_copyarea'
> powerpc64-linux-ld: drivers/video/fbdev/offb.o:(.data.rel.ro+0x68): undefined reference to `cfb_imageblit'
> 
> Fix this by allowing FB_OF any time that DRM_OFDRM != y so that the
> selected FB_CFB_* symbols will become =y instead of =m.
> 
> In tristate logic (for DRM_OFDRM), this changes the dependency from
>      !DRM_OFDRM	== 2 - 1 == 1 => modular only (or disabled)
> to (boolean)
>      DRM_OFDRM != y == y, allowing the 'select's to cause the
> FB_CFB_* symbols to =y instead of =m.
> 
> Fixes: c8a17756c425 ("drm/ofdrm: Add ofdrm for Open Firmware framebuffers")
> Signed-off-by: Randy Dunlap <rdunlap@...radead.org>
> Suggested-by: Masahiro Yamada <masahiroy@...nel.org>
> Cc: Thomas Zimmermann <tzimmermann@...e.de>
> Cc: Michal Suchánek <msuchanek@...e.de>
> Cc: linuxppc-dev@...ts.ozlabs.org
> Cc: Daniel Vetter <daniel@...ll.ch>
> Cc: Helge Deller <deller@....de>
> Cc: linux-fbdev@...r.kernel.org
> Cc: dri-devel@...ts.freedesktop.org

Acked-by: Thomas Zimmermann <tzimmermann@...e.de>

> ---
>   drivers/video/fbdev/Kconfig |    2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff -- a/drivers/video/fbdev/Kconfig b/drivers/video/fbdev/Kconfig
> --- a/drivers/video/fbdev/Kconfig
> +++ b/drivers/video/fbdev/Kconfig
> @@ -455,7 +455,7 @@ 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

-- 
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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