Messages in this thread | | | From | Doug Anderson <> | Date | Wed, 17 Aug 2022 14:33:32 -0700 | Subject | Re: [PATCH 5.18 0309/1095] drm/panel: Fix build error when CONFIG_DRM_PANEL_SAMSUNG_ATNA33XC20=y && CONFIG_DRM_DISPLAY_HELPER=m |
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Hi,
On Mon, Aug 15, 2022 at 12:09 PM Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote: > > From: Gao Chao <gaochao49@huawei.com> > > [ Upstream commit a67664860f7833015a683ea295f7c79ac2901332 ] > > If CONFIG_DRM_PANEL_SAMSUNG_ATNA33XC20=y && CONFIG_DRM_DISPLAY_HELPER=m, > bulding fails: > > drivers/gpu/drm/panel/panel-samsung-atna33xc20.o: In function `atana33xc20_probe': > panel-samsung-atna33xc20.c:(.text+0x744): undefined reference to > `drm_panel_dp_aux_backlight' > make: *** [vmlinux] Error 1 > > Let CONFIG_DRM_PANEL_SAMSUNG_ATNA33XC20 select DRM_DISPLAY_DP_HELPER and > CONFIG_DRM_DISPLAY_HELPER to fix this error. > > Fixes: 32ce3b320343 ("drm/panel: atna33xc20: Introduce the Samsung ATNA33XC20 panel") > Reported-by: Hulk Robot <hulkci@huawei.com> > Signed-off-by: Gao Chao <gaochao49@huawei.com> > Reviewed-by: Douglas Anderson <dianders@chromium.org> > Signed-off-by: Douglas Anderson <dianders@chromium.org> > Link: https://patchwork.freedesktop.org/patch/msgid/20220524024551.539-1-gaochao49@huawei.com > Signed-off-by: Sasha Levin <sashal@kernel.org> > --- > drivers/gpu/drm/panel/Kconfig | 2 ++ > 1 file changed, 2 insertions(+)
While it doesn't hurt to land this patch as-is on 5.18 and older kernels, it's not quite right. The symbols that this patch 'select' don't actually exist on 5.18. ;-) Doing a `git grep` of `DRM_DISPLAY_DP_HELPER` shows no hits except the one introduced in this patch...
If you want the equivalent fix for v5.18 and older, I believe you'd want:
select DRM_DP_HELPER select DRM_KMS_HELPER
See commit 3755d35ee1d2 ("drm/panel: Select DRM_DP_HELPER for DRM_PANEL_EDP") and commit 3c3384050d68 ("drm: Don't make DRM_PANEL_BRIDGE dependent on DRM_KMS_HELPERS") which added those for the (very similar) panel-edp.
The first of those is what got changed in v5.19 in commit 1e0f66420b13 ("drm/display: Introduce a DRM display-helper module")
So I guess the tl;dr:
* If you leave this patch in 5.18 (and 5.15), nothing bad will happen but the broken "randconfig" won't be fixed.
* If you revert this patch in 5.18 (and 5.15) also nothing bad will happen but also the broken "randconfig" won't be fixed.
* If someone cares about the randconfig on 5.15 / 5.18, we need a backport that adapts what's selected to the old symbol names.
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