Subject: [PATCH] media: i2c: fix max9271 build dependencies

From: Mauro Carvalho Chehab <[email-masked]>
Date: Mon, 8 Feb 2021 07:53:15 +0100

As described on its c file, the Maxim MAX9271 GMSL serializer isn't a
self-contained driver, as MAX9271 is usually embedded in camera modules
with at least one image sensor and optional additional components,
such as uController units or ISPs/DSPs.

After chanseset a59f853b3b4b ("media: i2c: Add driver for RDACM21 camera module"),
there are now two drivers currently needing it: rdacm20 and rdacm21.

Building with allmodconfig is now causing those warnings:

	WARNING: modpost: drivers/media/i2c/rdacm21-camera_module: 'max9271_set_serial_link' exported twice. Previous export was in drivers/media/i2c/rdacm20-camera_module.ko
	WARNING: modpost: drivers/media/i2c/rdacm21-camera_module: 'max9271_configure_i2c' exported twice. Previous export was in drivers/media/i2c/rdacm20-camera_module.ko
	WARNING: modpost: drivers/media/i2c/rdacm21-camera_module: 'max9271_set_high_threshold' exported twice. Previous export was in drivers/media/i2c/rdacm20-camera_module.ko
	WARNING: modpost: drivers/media/i2c/rdacm21-camera_module: 'max9271_configure_gmsl_link' exported twice. Previous export was in drivers/media/i2c/rdacm20-camera_module.ko
	WARNING: modpost: drivers/media/i2c/rdacm21-camera_module: 'max9271_set_gpios' exported twice. Previous export was in drivers/media/i2c/rdacm20-camera_module.ko
	WARNING: modpost: drivers/media/i2c/rdacm21-camera_module: 'max9271_clear_gpios' exported twice. Previous export was in drivers/media/i2c/rdacm20-camera_module.ko
	WARNING: modpost: drivers/media/i2c/rdacm21-camera_module: 'max9271_enable_gpios' exported twice. Previous export was in drivers/media/i2c/rdacm20-camera_module.ko
	WARNING: modpost: drivers/media/i2c/rdacm21-camera_module: 'max9271_disable_gpios' exported twice. Previous export was in drivers/media/i2c/rdacm20-camera_module.ko
	WARNING: modpost: drivers/media/i2c/rdacm21-camera_module: 'max9271_verify_id' exported twice. Previous export was in drivers/media/i2c/rdacm20-camera_module.ko
	WARNING: modpost: drivers/media/i2c/rdacm21-camera_module: 'max9271_set_address' exported twice. Previous export was in drivers/media/i2c/rdacm20-camera_module.ko
	WARNING: modpost: drivers/media/i2c/rdacm21-camera_module: 'max9271_set_deserializer_address' exported twice. Previous export was in drivers/media/i2c/rdacm20-camera_module.ko
	WARNING: modpost: drivers/media/i2c/rdacm21-camera_module: 'max9271_set_translation' exported twice. Previous export was in drivers/media/i2c/rdacm20-camera_module.ko

Address the issue by adding a Kconfig item for it, that it is
seleced if either one of the modules that need max9271 is used.

Reported-by: Stephen Rothwell <[email-masked]>
Fixes: a59f853b3b4b ("media: i2c: Add driver for RDACM21 camera module")
Signed-off-by: Mauro Carvalho Chehab <[email-masked]>
---
 drivers/media/i2c/Kconfig  | 10 ++++++++++
 drivers/media/i2c/Makefile |  8 ++++----
 2 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
index 2d3dc0d82f9e..a6802195d583 100644
--- a/drivers/media/i2c/Kconfig
+++ b/drivers/media/i2c/Kconfig
@@ -712,6 +712,16 @@ config VIDEO_ST_MIPID02
 	  module will be called st-mipid02.
 endmenu
 
+#
+# Camera ancillary chips
+#
+
+# MAX9271 is usually embedded in camera modules
+config VIDEO_MAX9271_SERIALIZER
+	tristate
+	default y
+	depends on VIDEO_RDACM20 || VIDEO_RDACM21
+
 #
 # V4L2 I2C drivers that are related with Camera support
 #
diff --git a/drivers/media/i2c/Makefile b/drivers/media/i2c/Makefile
index 6bd22d63e1a7..63bb16e51876 100644
--- a/drivers/media/i2c/Makefile
+++ b/drivers/media/i2c/Makefile
@@ -125,10 +125,10 @@ obj-$(CONFIG_VIDEO_IMX319)	+= imx319.o
 obj-$(CONFIG_VIDEO_IMX334)	+= imx334.o
 obj-$(CONFIG_VIDEO_IMX355)	+= imx355.o
 obj-$(CONFIG_VIDEO_MAX9286)	+= max9286.o
-rdacm20-camera_module-objs	:= rdacm20.o max9271.o
-obj-$(CONFIG_VIDEO_RDACM20)	+= rdacm20-camera_module.o
-rdacm21-camera_module-objs	:= rdacm21.o max9271.o
-obj-$(CONFIG_VIDEO_RDACM21)	+= rdacm21-camera_module.o
+obj-$(CONFIG_VIDEO_RDACM20)	+= rdacm20.o
+obj-$(CONFIG_VIDEO_RDACM21)	+= rdacm21.o
 obj-$(CONFIG_VIDEO_ST_MIPID02) += st-mipid02.o
 
+obj-$(CONFIG_VIDEO_MAX9271_SERIALIZER) += max9271.o
+
 obj-$(CONFIG_SDR_MAX2175) += max2175.o
-- 
2.29.2