Hi Arnd, On 11/23/22 01:08, Arnd Bergmann wrote: > On Wed, Nov 23, 2022, at 04:16, Randy Dunlap wrote: >> 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. >> > > Is it actually a useful configuration to have OFDRM=m and > FB_OF=y though? I would expect in that case that the OFDRM > driver never binds to a device because it's already owned > by FB_OF. > >> 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 > > I would instead make this 'depends on DRM_OFDRM=n', which > completely eliminates configs that have both driver enabled. Yep, that works for me. Thanks. Thomas, Michal, are you OK with that change? > A nicer change would be to make FB_OF a tristate symbol, > which makes it possible to load one of the two modules if > both are enabled =m, while only allowing one of them to > be =y if the other is completely disabled. It looks like > offb was originally written to be usable as a loadable module, > but Kconfig has prevented this since at least the start of > the git history. -- ~Randy
