Messages in this thread | | | Subject | Re: [PATCH] drm/panel-edp: modify Kconfig to prevent build error | From | Randy Dunlap <> | Date | Wed, 17 Nov 2021 12:04:33 -0800 |
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On 11/16/21 11:58 PM, Arnd Bergmann wrote: > On Wed, Nov 17, 2021 at 7:27 AM Randy Dunlap <rdunlap@infradead.org> wrote: >> >> When CONFIG_DRM_KMS_HELPER=m and CONFIG_DRM_PANEL_EDP=y, >> there is a build error in gpu/drm/panel/panel-edp.o: >> >> arm-linux-gnueabi-ld: drivers/gpu/drm/panel/panel-edp.o: in function `panel_edp_probe': >> panel-edp.c:(.text+0xf38): undefined reference to `drm_panel_dp_aux_backlight' >> >> Fix this by limiting DRM_PANEL_DEP by the value of the DRM_KMS_HELPER >> symbol. > > I think the analysis is correct, but this is not the correct fix since > DRM_KMS_HELPER > is not user-selectable. (Almost) all other drivers that rely on DRM_KMS_HELPER > use 'select' for this, and mixing the two risks running into circular > dependencies.
Oops. Thanks for catching that.
My first (local) version of the patch used select, but that got me into kconfig circular dependency chain land (ugly). Maybe your all-at-once patch can take care of that problem.
> > I see that there are already some 'depends on DRM_KMS_HELPER' in bridge > and panel drivers, so it's possible that we have to fix them all at the same to > do this right. I ran into another problem like this the other day and > I'm currently > testing with the patch below, but I have not posted that yet since I am not > fully convinced that this is the correct fix either.
I'll test some with it also.
thanks.
-- ~Randy
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