drm/dp: Move DisplayPort helpers into separate helper module

Move DisplayPort functions into a separate module to reduce the size
of the KMS helpers. Select DRM_DP_HELPER for all users of the code. To
avoid naming conflicts, rename drm_dp_helper.c to drm_dp.c

This change can help to reduce the size of the kernel binary. Some
numbers from a x86-64 test build:

Before:
	drm_kms_helper.ko:	447480 bytes

After:
	drm_dp_helper.ko:	216632 bytes
	drm_kms_helper.ko:	239424 bytes

For early-boot graphics, generic DRM drivers, such as simpledrm,
require DRM KMS helpers to be built into the kernel. Generic helper
functions for DisplayPort take up a significant portion of DRM KMS
helper library. These functions are not used by generic drivers and
can be loaded as a module.

v3:
	* fix include statement in DRM selftests
v2:
	* move DP helper code into dp/ (Jani)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Lyude Paul <lyude@redhat.com>
Acked-by: Daniel Vetter <daniel@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20220114114535.29157-4-tzimmermann@suse.de

drivers/gpu/drm/Kconfig

@@ -80,6 +80,12 @@ config DRM_DEBUG_SELFTEST
 
 	  If in doubt, say "N".
 
+config DRM_DP_HELPER
+	tristate
+	depends on DRM
+	help
+	  DRM helpers for DisplayPort.
+
 config DRM_KMS_HELPER
 	tristate
 	depends on DRM
@@ -236,6 +242,7 @@ config DRM_RADEON
 	depends on DRM && PCI && MMU
 	depends on AGP || !AGP
 	select FW_LOADER
+	select DRM_DP_HELPER
         select DRM_KMS_HELPER
         select DRM_TTM
 	select DRM_TTM_HELPER
@@ -256,6 +263,7 @@ config DRM_AMDGPU
 	tristate "AMD GPU"
 	depends on DRM && PCI && MMU
 	select FW_LOADER
+	select DRM_DP_HELPER
 	select DRM_KMS_HELPER
 	select DRM_SCHED
 	select DRM_TTM

drivers/gpu/drm/Makefile

@@ -48,21 +48,18 @@ obj-$(CONFIG_DRM_VRAM_HELPER) += drm_vram_helper.o
 drm_ttm_helper-y := drm_gem_ttm_helper.o
 obj-$(CONFIG_DRM_TTM_HELPER) += drm_ttm_helper.o
 
-drm_kms_helper-y := drm_bridge_connector.o drm_crtc_helper.o drm_dp_helper.o \
+drm_kms_helper-y := drm_bridge_connector.o drm_crtc_helper.o \
 		drm_dsc.o drm_encoder_slave.o drm_flip_work.o drm_hdcp.o \
 		drm_probe_helper.o \
-		drm_plane_helper.o drm_dp_mst_topology.o drm_atomic_helper.o \
+		drm_plane_helper.o drm_atomic_helper.o \
-		drm_kms_helper_common.o drm_dp_dual_mode_helper.o \
+		drm_kms_helper_common.o \
 		drm_simple_kms_helper.o drm_modeset_helper.o \
 		drm_scdc_helper.o drm_gem_atomic_helper.o \
 		drm_gem_framebuffer_helper.o \
 		drm_atomic_state_helper.o drm_damage_helper.o \
 		drm_format_helper.o drm_self_refresh_helper.o drm_rect.o
-
 drm_kms_helper-$(CONFIG_DRM_PANEL_BRIDGE) += bridge/panel.o
 drm_kms_helper-$(CONFIG_DRM_FBDEV_EMULATION) += drm_fb_helper.o
-drm_kms_helper-$(CONFIG_DRM_DP_AUX_CHARDEV) += drm_dp_aux_dev.o
-drm_kms_helper-$(CONFIG_DRM_DP_CEC) += drm_dp_cec.o
 
 obj-$(CONFIG_DRM_KMS_HELPER) += drm_kms_helper.o
 obj-$(CONFIG_DRM_DEBUG_SELFTEST) += selftests/
@@ -72,6 +69,7 @@ obj-$(CONFIG_DRM_MIPI_DBI) += drm_mipi_dbi.o
 obj-$(CONFIG_DRM_MIPI_DSI) += drm_mipi_dsi.o
 obj-$(CONFIG_DRM_PANEL_ORIENTATION_QUIRKS) += drm_panel_orientation_quirks.o
 obj-y			+= arm/
+obj-y			+= dp/
 obj-$(CONFIG_DRM_TTM)	+= ttm/
 obj-$(CONFIG_DRM_SCHED)	+= scheduler/
 obj-$(CONFIG_DRM_TDFX)	+= tdfx/

drivers/gpu/drm/bridge/Kconfig

@@ -184,6 +184,7 @@ config DRM_PARADE_PS8640
 	tristate "Parade PS8640 MIPI DSI to eDP Converter"
 	depends on OF
 	select DRM_DP_AUX_BUS
+	select DRM_DP_HELPER
 	select DRM_KMS_HELPER
 	select DRM_MIPI_DSI
 	select DRM_PANEL
@@ -254,6 +255,7 @@ config DRM_TOSHIBA_TC358764
 config DRM_TOSHIBA_TC358767
 	tristate "Toshiba TC358767 eDP bridge"
 	depends on OF
+	select DRM_DP_HELPER
 	select DRM_KMS_HELPER
 	select REGMAP_I2C
 	select DRM_PANEL
@@ -273,6 +275,7 @@ config DRM_TOSHIBA_TC358768
 config DRM_TOSHIBA_TC358775
 	tristate "Toshiba TC358775 DSI/LVDS bridge"
 	depends on OF
+	select DRM_DP_HELPER
 	select DRM_KMS_HELPER
 	select REGMAP_I2C
 	select DRM_PANEL
@@ -300,6 +303,7 @@ config DRM_TI_SN65DSI83
 config DRM_TI_SN65DSI86
 	tristate "TI SN65DSI86 DSI to eDP bridge"
 	depends on OF
+	select DRM_DP_HELPER
 	select DRM_KMS_HELPER
 	select REGMAP_I2C
 	select DRM_PANEL

drivers/gpu/drm/bridge/analogix/Kconfig

@@ -3,6 +3,7 @@ config DRM_ANALOGIX_ANX6345
 	tristate "Analogix ANX6345 bridge"
 	depends on OF
 	select DRM_ANALOGIX_DP
+	select DRM_DP_HELPER
 	select DRM_KMS_HELPER
 	select REGMAP_I2C
 	help
@@ -14,6 +15,7 @@ config DRM_ANALOGIX_ANX6345
 config DRM_ANALOGIX_ANX78XX
 	tristate "Analogix ANX78XX bridge"
 	select DRM_ANALOGIX_DP
+	select DRM_DP_HELPER
 	select DRM_KMS_HELPER
 	select REGMAP_I2C
 	help

drivers/gpu/drm/bridge/cadence/Kconfig

@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0-only
 config DRM_CDNS_MHDP8546
 	tristate "Cadence DPI/DP bridge"
+	select DRM_DP_HELPER
 	select DRM_KMS_HELPER
 	select DRM_PANEL_BRIDGE
 	depends on OF

drivers/gpu/drm/dp/Makefile

@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: MIT
+
+drm_dp_helper-y := drm_dp.o drm_dp_dual_mode_helper.o drm_dp_helper_mod.o drm_dp_mst_topology.o
+drm_dp_helper-$(CONFIG_DRM_DP_AUX_CHARDEV) += drm_dp_aux_dev.o
+drm_dp_helper-$(CONFIG_DRM_DP_CEC) += drm_dp_cec.o
+
+obj-$(CONFIG_DRM_DP_HELPER) += drm_dp_helper.o

drivers/gpu/drm/dp/drm_dp_helper_mod.c

@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: MIT
+
+#include <linux/module.h>
+
+#include "drm_dp_helper_internal.h"
+
+MODULE_DESCRIPTION("DRM DisplayPort helper");
+MODULE_LICENSE("GPL and additional rights");
+
+static int __init drm_dp_helper_module_init(void)
+{
+	return drm_dp_aux_dev_init();
+}
+
+static void __exit drm_dp_helper_module_exit(void)
+{
+	/* Call exit functions from specific dp helpers here */
+	drm_dp_aux_dev_exit();
+}
+
+module_init(drm_dp_helper_module_init);
+module_exit(drm_dp_helper_module_exit);

drivers/gpu/drm/drm_kms_helper_common.c

@@ -29,7 +29,6 @@
 
 #include <drm/drm_print.h>
 
-#include "drm_dp_helper_internal.h"
 #include "drm_crtc_helper_internal.h"
 
 MODULE_AUTHOR("David Airlie, Jesse Barnes");
@@ -62,17 +61,3 @@ MODULE_PARM_DESC(edid_firmware,
 		 "DEPRECATED. Use drm.edid_firmware module parameter instead.");
 
 #endif
-
-static int __init drm_kms_helper_init(void)
-{
-	return drm_dp_aux_dev_init();
-}
-
-static void __exit drm_kms_helper_exit(void)
-{
-	/* Call exit functions from specific kms helpers here */
-	drm_dp_aux_dev_exit();
-}
-
-module_init(drm_kms_helper_init);
-module_exit(drm_kms_helper_exit);

drivers/gpu/drm/i915/Kconfig

@@ -9,6 +9,7 @@ config DRM_I915
 	# the shmem_readpage() which depends upon tmpfs
 	select SHMEM
 	select TMPFS
+	select DRM_DP_HELPER
 	select DRM_KMS_HELPER
 	select DRM_PANEL
 	select DRM_MIPI_DSI

drivers/gpu/drm/msm/Kconfig

@@ -12,6 +12,7 @@ config DRM_MSM
 	select IOMMU_IO_PGTABLE
 	select QCOM_MDT_LOADER if ARCH_QCOM
 	select REGULATOR
+	select DRM_DP_HELPER
 	select DRM_KMS_HELPER
 	select DRM_PANEL
 	select DRM_BRIDGE

drivers/gpu/drm/nouveau/Kconfig

@@ -4,6 +4,7 @@ config DRM_NOUVEAU
 	depends on DRM && PCI && MMU
 	select IOMMU_API
 	select FW_LOADER
+	select DRM_DP_HELPER
 	select DRM_KMS_HELPER
 	select DRM_TTM
 	select DRM_TTM_HELPER

drivers/gpu/drm/rockchip/Kconfig

@@ -2,6 +2,7 @@
 config DRM_ROCKCHIP
 	tristate "DRM Support for Rockchip"
 	depends on DRM && ROCKCHIP_IOMMU
+	select DRM_DP_HELPER
 	select DRM_GEM_CMA_HELPER
 	select DRM_KMS_HELPER
 	select DRM_PANEL

drivers/gpu/drm/selftests/test-drm_dp_mst_helper.c

@@ -10,7 +10,7 @@
 #include <drm/drm_dp_mst_helper.h>
 #include <drm/drm_print.h>
 
-#include "../drm_dp_mst_topology_internal.h"
+#include "../dp/drm_dp_mst_topology_internal.h"
 #include "test-drm_modeset_common.h"
 
 int igt_dp_mst_calc_pbn_mode(void *ignored)

drivers/gpu/drm/tegra/Kconfig

@@ -5,6 +5,7 @@ config DRM_TEGRA
 	depends on COMMON_CLK
 	depends on DRM
 	depends on OF
+	select DRM_DP_HELPER
 	select DRM_KMS_HELPER
 	select DRM_MIPI_DSI
 	select DRM_PANEL

drivers/gpu/drm/xlnx/Kconfig

@@ -6,6 +6,7 @@ config DRM_ZYNQMP_DPSUB
 	depends on PHY_XILINX_ZYNQMP
 	depends on XILINX_ZYNQMP_DPDMA
 	select DMA_ENGINE
+	select DRM_DP_HELPER
 	select DRM_GEM_CMA_HELPER
 	select DRM_KMS_HELPER
 	select GENERIC_PHY