media: v4l: async, fwnode: Improve module organisation

The V4L2 async framework is generally used with the V4L2 fwnode, which
also depends on the former. There are a few exceptions but they are
relatively few.

At the same time there is a vast number of systems that need videodev
module, but have no use for v4l2-async that's now part of videodev.

In order to improve, split the v4l2-async into its own module. Selecting
V4L2_FWNODE also selects V4L2_ASYNC.

This also moves the initialisation of the debufs entries for async subdevs
to loading of the v4l2-async module. The directory is named as
"v4l2-async".

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Ezequiel Garcia <ezequiel@collabora.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

drivers/media/i2c/Kconfig

@@ -217,6 +217,7 @@ config VIDEO_ADV7180
 	depends on GPIOLIB && VIDEO_V4L2 && I2C
 	select MEDIA_CONTROLLER
 	select VIDEO_V4L2_SUBDEV_API
+	select V4L2_ASYNC
 	help
 	  Support for the Analog Devices ADV7180 video decoder.
 
@@ -534,6 +535,7 @@ config VIDEO_ADV7175
 config VIDEO_ADV7343
 	tristate "ADV7343 video encoder"
 	depends on I2C
+	select V4L2_ASYNC
 	help
 	  Support for Analog Devices I2C bus based ADV7343 encoder.
 
@@ -652,6 +654,7 @@ config SDR_MAX2175
 	tristate "Maxim 2175 RF to Bits tuner"
 	depends on VIDEO_V4L2 && MEDIA_SDR_SUPPORT && I2C
 	select REGMAP_I2C
+	select V4L2_ASYNC
 	help
 	  Support for Maxim 2175 tuner. It is an advanced analog/digital
 	  radio receiver with RF-to-Bits front-end designed for SDR solutions.
@@ -668,6 +671,7 @@ menu "Miscellaneous helper chips"
 config VIDEO_THS7303
 	tristate "THS7303/53 Video Amplifier"
 	depends on VIDEO_V4L2 && I2C
+	select V4L2_ASYNC
 	help
 	  Support for TI THS7303/53 video amplifier
 
@@ -1341,6 +1345,7 @@ config VIDEO_AD5820
 	tristate "AD5820 lens voice coil support"
 	depends on GPIOLIB && I2C && VIDEO_V4L2
 	select MEDIA_CONTROLLER
+	select V4L2_ASYNC
 	help
 	  This is a driver for the AD5820 camera lens voice coil.
 	  It is used for example in Nokia N900 (RX-51).
@@ -1350,6 +1355,7 @@ config VIDEO_AK7375
 	depends on I2C && VIDEO_V4L2
 	select MEDIA_CONTROLLER
 	select VIDEO_V4L2_SUBDEV_API
+	select V4L2_ASYNC
 	help
 	  This is a driver for the AK7375 camera lens voice coil.
 	  AK7375 is a 12 bit DAC with 120mA output current sink
@@ -1361,6 +1367,7 @@ config VIDEO_DW9714
 	depends on I2C && VIDEO_V4L2
 	select MEDIA_CONTROLLER
 	select VIDEO_V4L2_SUBDEV_API
+	select V4L2_ASYNC
 	help
 	  This is a driver for the DW9714 camera lens voice coil.
 	  DW9714 is a 10 bit DAC with 120mA output current sink
@@ -1384,6 +1391,7 @@ config VIDEO_DW9807_VCM
 	depends on I2C && VIDEO_V4L2
 	select MEDIA_CONTROLLER
 	select VIDEO_V4L2_SUBDEV_API
+	select V4L2_ASYNC
 	help
 	  This is a driver for the DW9807 camera lens voice coil.
 	  DW9807 is a 10 bit DAC with 100mA output current sink
@@ -1399,6 +1407,7 @@ config VIDEO_ADP1653
 	tristate "ADP1653 flash support"
 	depends on I2C && VIDEO_V4L2
 	select MEDIA_CONTROLLER
+	select V4L2_ASYNC
 	help
 	  This is a driver for the ADP1653 flash controller. It is used for
 	  example in Nokia N900.
@@ -1408,6 +1417,7 @@ config VIDEO_LM3560
 	depends on I2C && VIDEO_V4L2
 	select MEDIA_CONTROLLER
 	select REGMAP_I2C
+	select V4L2_ASYNC
 	help
 	  This is a driver for the lm3560 dual flash controllers. It controls
 	  flash, torch LEDs.
@@ -1417,6 +1427,7 @@ config VIDEO_LM3646
 	depends on I2C && VIDEO_V4L2
 	select MEDIA_CONTROLLER
 	select REGMAP_I2C
+	select V4L2_ASYNC
 	help
 	  This is a driver for the lm3646 dual flash controllers. It controls
 	  flash, torch LEDs.

drivers/media/v4l2-core/Kconfig

@@ -62,6 +62,7 @@ config V4L2_FLASH_LED_CLASS
 	tristate "V4L2 flash API for LED flash class devices"
 	depends on VIDEO_V4L2 && VIDEO_V4L2_SUBDEV_API
 	depends on LEDS_CLASS_FLASH
+	select V4L2_ASYNC
 	help
 	  Say Y here to enable V4L2 flash API support for LED flash
 	  class drivers.
@@ -70,6 +71,10 @@ config V4L2_FLASH_LED_CLASS
 
 config V4L2_FWNODE
 	tristate
+	select V4L2_ASYNC
+
+config V4L2_ASYNC
+	tristate
 
 # Used by drivers that need Videobuf modules
 config VIDEOBUF_GEN

drivers/media/v4l2-core/Makefile

@@ -6,7 +6,7 @@
 tuner-objs	:=	tuner-core.o
 
 videodev-objs	:=	v4l2-dev.o v4l2-ioctl.o v4l2-device.o v4l2-fh.o \
-			v4l2-event.o v4l2-subdev.o v4l2-async.o v4l2-common.o \
+			v4l2-event.o v4l2-subdev.o v4l2-common.o \
 			v4l2-ctrls-core.o v4l2-ctrls-api.o \
 			v4l2-ctrls-request.o v4l2-ctrls-defs.o
 videodev-$(CONFIG_COMPAT) += v4l2-compat-ioctl32.o
@@ -15,8 +15,9 @@ videodev-$(CONFIG_MEDIA_CONTROLLER) += v4l2-mc.o
 videodev-$(CONFIG_SPI) += v4l2-spi.o
 videodev-$(CONFIG_VIDEO_V4L2_I2C) += v4l2-i2c.o
 
-obj-$(CONFIG_V4L2_FWNODE) += v4l2-fwnode.o
 obj-$(CONFIG_VIDEO_V4L2) += videodev.o
+obj-$(CONFIG_V4L2_FWNODE) += v4l2-fwnode.o
+obj-$(CONFIG_V4L2_ASYNC) += v4l2-async.o
 obj-$(CONFIG_VIDEO_V4L2) += v4l2-dv-timings.o
 
 obj-$(CONFIG_VIDEO_TUNER) += tuner.o

drivers/media/v4l2-core/v4l2-async.c

@@ -854,8 +854,27 @@ static int pending_subdevs_show(struct seq_file *s, void *data)
 }
 DEFINE_SHOW_ATTRIBUTE(pending_subdevs);
 
-void v4l2_async_debug_init(struct dentry *debugfs_dir)
+static struct dentry *v4l2_async_debugfs_dir;
+
+static int __init v4l2_async_init(void)
 {
-	debugfs_create_file("pending_async_subdevices", 0444, debugfs_dir, NULL,
+	v4l2_async_debugfs_dir = debugfs_create_dir("v4l2-async", NULL);
+	debugfs_create_file("pending_async_subdevices", 0444,
+			    v4l2_async_debugfs_dir, NULL,
 			    &pending_subdevs_fops);
+
+	return 0;
 }
+
+static void __exit v4l2_async_exit(void)
+{
+	debugfs_remove_recursive(v4l2_async_debugfs_dir);
+}
+
+subsys_initcall(v4l2_async_init);
+module_exit(v4l2_async_exit);
+
+MODULE_AUTHOR("Guennadi Liakhovetski <g.liakhovetski@gmx.de>");
+MODULE_AUTHOR("Sakari Ailus <sakari.ailus@linux.intel.com>");
+MODULE_AUTHOR("Ezequiel Garcia <ezequiel@collabora.com>");
+MODULE_LICENSE("GPL");

drivers/media/v4l2-core/v4l2-dev.c

@@ -39,8 +39,6 @@
 		       __func__, ##arg);				\
 } while (0)
 
-static struct dentry *v4l2_debugfs_dir;
-
 /*
  *	sysfs stuff
  */
@@ -1121,8 +1119,6 @@ static int __init videodev_init(void)
 		return -EIO;
 	}
 
-	v4l2_debugfs_dir = debugfs_create_dir("video4linux", NULL);
-	v4l2_async_debug_init(v4l2_debugfs_dir);
 	return 0;
 }
 
@@ -1130,7 +1126,6 @@ static void __exit videodev_exit(void)
 {
 	dev_t dev = MKDEV(VIDEO_MAJOR, 0);
 
-	debugfs_remove_recursive(v4l2_debugfs_dir);
 	class_unregister(&video_class);
 	unregister_chrdev_region(dev, VIDEO_NUM_DEVICES);
 }