[PATCH] drm/bridge-connector: select DRM_DISPLAY_HELPER from DRM_BRIDGE_CONNECTOR

[Dmitry Baryshkov]

On Fri, Oct 18, 2024 at 04:01:17PM +0000, Arnd Bergmann wrote:
> On Fri, Oct 18, 2024, at 15:42, Dmitry Baryshkov wrote:
> > On Fri, Oct 18, 2024 at 03:08:45PM +0000, Arnd Bergmann wrote:
> >> From: Arnd Bergmann <arnd at arndb.de>
> >> 
> >> The imx display drivers use the new bridge connector helpers but don't
> >> explicitly select CONFIG_DRM_DISPLAY_HELPER, leading to a link failure
> >> in rare configurations:
> >> 
> >> ld.lld-20: error: undefined symbol: drm_bridge_connector_init
> >> >>> referenced by imx-ldb.c
> >> >>>               drivers/gpu/drm/imx/ipuv3/imx-ldb.o:(imx_ldb_bind) in archive vmlinux.a
> >> >>> referenced by parallel-display.c
> >> >>>               drivers/gpu/drm/imx/ipuv3/parallel-display.o:(imx_pd_bind) in archive vmlinux.a
> >> 
> >> Move DRM_BRIDGE_CONNECTOR out of the DRM_DISPLAY_HELPER block and
> >> instead select that symbol indirectly.
> >> 
> >> Fixes: f94b9707a1c9 ("drm/imx: parallel-display: switch to imx_legacy_bridge / drm_bridge_connector")
> >> Signed-off-by: Arnd Bergmann <arnd at arndb.de>
> >
> > I think a correct fix is to select DRM_DISPLAY_HELPER instead.
> 
> I think I just didn't express that clearly enough, selecting
> DRM_DISPLAY_HELPER is what I did and what I tried to explain:
> 
> >>  config DRM_BRIDGE_CONNECTOR
> >>  	bool
> >>  	select DRM_DISPLAY_HDMI_STATE_HELPER
> >> +	select DRM_DISPLAY_HELPER
> >>  	help
> >>  	  DRM connector implementation terminating DRM bridge chains.
> 
> I had to move the 'if' block just to avoid a circular
> dependency.
> 
> Or did you mean the imx driver is the one that should
> 'select DRM_DISPLAY_HELPER'? That would also work, but
> adds a bit more complexity.

Yes, I proposed this solution. I think this is what other drivers do.


-- 
With best wishes
Dmitry