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.
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.
Arnd --- commit a836092fedaac66af03ea9ed7cb13214fd2ab8a2 Author: Arnd Bergmann arnd@arndb.de Date: Mon Nov 15 16:54:04 2021 +0100
drm/mipi-dbi: select CONFIG_DRM_KMS_HELPER
The driver fails to build when the KMS helpers are disabled:
ld.lld: error: undefined symbol: drm_gem_fb_get_obj >>> referenced by drm_mipi_dbi.c >>> gpu/drm/drm_mipi_dbi.o:(mipi_dbi_buf_copy) in archive drivers/built-in.a >>> referenced by drm_mipi_dbi.c >>> gpu/drm/drm_mipi_dbi.o:(mipi_dbi_fb_dirty) in archive drivers/built-in.a
ld.lld: error: undefined symbol: drm_gem_fb_begin_cpu_access >>> referenced by drm_mipi_dbi.c >>> gpu/drm/drm_mipi_dbi.o:(mipi_dbi_buf_copy) in archive drivers/built-in.a
ld.lld: error: undefined symbol: drm_fb_swab >>> referenced by drm_mipi_dbi.c >>> gpu/drm/drm_mipi_dbi.o:(mipi_dbi_buf_copy) in archive drivers/built-in.a
ld.lld: error: undefined symbol: drm_fb_xrgb8888_to_rgb565 >>> referenced by drm_mipi_dbi.c >>> gpu/drm/drm_mipi_dbi.o:(mipi_dbi_buf_copy) in archive drivers/built-in.a
ld.lld: error: undefined symbol: drm_fb_memcpy >>> referenced by drm_mipi_dbi.c >>> gpu/drm/drm_mipi_dbi.o:(mipi_dbi_buf_copy) in archive drivers/built-in.a
This is fairly hard to hit in randconfig drivers, but it eventually did trigger for me in a configuration where all other DRM drivers are loadable modules, but DRM_PANEL_WIDECHIPS_WS2401 was built-in.
Signed-off-by: Arnd Bergmann arnd@arndb.de
diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig index 0039df26854b..a03c2761c5f9 100644 --- a/drivers/gpu/drm/Kconfig +++ b/drivers/gpu/drm/Kconfig @@ -29,6 +29,7 @@ menuconfig DRM
config DRM_MIPI_DBI tristate + select DRM_KMS_HELPER depends on DRM
config DRM_MIPI_DSI diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig index 431b6e12a81f..17a8d603e7d8 100644 --- a/drivers/gpu/drm/bridge/Kconfig +++ b/drivers/gpu/drm/bridge/Kconfig @@ -8,7 +8,6 @@ config DRM_BRIDGE config DRM_PANEL_BRIDGE def_bool y depends on DRM_BRIDGE - depends on DRM_KMS_HELPER select DRM_PANEL help DRM bridge wrapper of DRM panels diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig index cfc8d644cedf..40ec20f3552d 100644 --- a/drivers/gpu/drm/panel/Kconfig +++ b/drivers/gpu/drm/panel/Kconfig @@ -140,9 +140,8 @@ config DRM_PANEL_ILITEK_IL9322 config DRM_PANEL_ILITEK_ILI9341 tristate "Ilitek ILI9341 240x320 QVGA panels" depends on OF && SPI - depends on DRM_KMS_HELPER - depends on DRM_KMS_CMA_HELPER depends on BACKLIGHT_CLASS_DEVICE + select DRM_KMS_CMA_HELPER select DRM_MIPI_DBI help Say Y here if you want to enable support for Ilitek IL9341