On Tuesday 26 January 2016 12:33:08 Mauro Carvalho Chehab wrote:

Em Tue, 26 Jan 2016 15:10:00 +0100
Arnd Bergmann [off-list ref] escreveu:

quoted

em28xx selects VIDEO_TUNER, which has a dependency on MEDIA_TUNER,
so we get a Kconfig warning if that is disabled:

warning: (VIDEO_PVRUSB2 && VIDEO_USBVISION && VIDEO_GO7007 && VIDEO_AU0828_V4L2 && VIDEO_CX231XX && VIDEO_TM6000 && VIDEO_EM28XX && VIDEO_IVTV && VIDEO_MXB && VIDEO_CX18 && VIDEO_CX23885 && VIDEO_CX88 && VIDEO_BT848 && VIDEO_SAA7134 && VIDEO_SAA7164) selects VIDEO_TUNER which has unmet direct dependencies (MEDIA_SUPPORT && MEDIA_TUNER)

This warning is bogus, as it is OK to select VIDEO_TUNER even if MEDIA_TUNER
is not defined.

See how MEDIA_TUNER is defined:


config MEDIA_TUNER
	tristate
	depends on (MEDIA_ANALOG_TV_SUPPORT || MEDIA_DIGITAL_TV_SUPPORT || MEDIA_RADIO_SUPPORT || MEDIA_SDR_SUPPORT) && I2C
	default y
	select MEDIA_TUNER_XC2028 if MEDIA_SUBDRV_AUTOSELECT
	select MEDIA_TUNER_XC5000 if MEDIA_SUBDRV_AUTOSELECT
	select MEDIA_TUNER_XC4000 if MEDIA_SUBDRV_AUTOSELECT
	select MEDIA_TUNER_MT20XX if MEDIA_SUBDRV_AUTOSELECT
	select MEDIA_TUNER_TDA8290 if MEDIA_SUBDRV_AUTOSELECT
	select MEDIA_TUNER_TEA5761 if MEDIA_SUBDRV_AUTOSELECT && MEDIA_RADIO_SUPPORT
	select MEDIA_TUNER_TEA5767 if MEDIA_SUBDRV_AUTOSELECT && MEDIA_RADIO_SUPPORT
	select MEDIA_TUNER_SIMPLE if MEDIA_SUBDRV_AUTOSELECT
	select MEDIA_TUNER_TDA9887 if MEDIA_SUBDRV_AUTOSELECT
	select MEDIA_TUNER_MC44S803 if MEDIA_SUBDRV_AUTOSELECT

MEDIA_TUNER is just one of the media Kconfig workarounds to its limitation of
not allowing to select a device that has dependencies. It is true if the user
selected either TV or radio media devices. It works together with 
MEDIA_SUBDRV_AUTOSELECT. When both are enabled, it selects all
media tuners. That makes easier for end users to not need to worry about
manually selecting the needed tuners.

Advanced users may, instead, manually select the media tuner that his
hardware needs. In such case, it doesn't matter if MEDIA_TUNER
is enabled or not.

As this is due to a Kconfig limitation, I've no idea how to fix or get
hid of it, but making em28xx dependent of MEDIA_TUNER is wrong.

I don't understand what limitation you see here. The definition
of the VIDEO_TUNER symbol is an empty 'tristate' symbol with a
dependency on MEDIA_TUNER to ensure we get a warning if MEDIA_TUNER
is not enabled, and to ensure it is set to 'm' if MEDIA_TUNER=m and
a "bool" driver selects VIDEO_TUNER.

You are saying that the first one is not correct, so I assume we
still need the second meaning. We could probably do that like the
patch below (untested) that makes the intention much more explicit.

	Arnd

diff --git a/drivers/media/v4l2-core/Kconfig b/drivers/media/v4l2-core/Kconfig
index 9beece00869b..1050bdf1848f 100644
--- a/drivers/media/v4l2-core/Kconfig
+++ b/drivers/media/v4l2-core/Kconfig

@@ -37,7 +37,11 @@ config VIDEO_PCI_SKELETON
 # Used by drivers that need tuner.ko
 config VIDEO_TUNER
 	tristate
-	depends on MEDIA_TUNER
+
+config VIDEO_TUNER_MODULE
+	tristate # must not be built-in if MEDIA_TUNER=m because of I2C
+	default y if VIDEO_TUNER=y || MEDIA_TUNER=y
+	default m if VIDEO_TUNER=m
 
 # Used by drivers that need v4l2-mem2mem.ko
 config V4L2_MEM2MEM_DEV

diff --git a/drivers/media/v4l2-core/Makefile b/drivers/media/v4l2-core/Makefile
index 1dc8bba2b198..971af6398d6d 100644
--- a/drivers/media/v4l2-core/Makefile
+++ b/drivers/media/v4l2-core/Makefile

@@ -21,7 +21,7 @@ obj-$(CONFIG_VIDEO_V4L2) += videodev.o
 obj-$(CONFIG_VIDEO_V4L2) += v4l2-common.o
 obj-$(CONFIG_VIDEO_V4L2) += v4l2-dv-timings.o
 
-obj-$(CONFIG_VIDEO_TUNER) += tuner.o
+obj-$(CONFIG_VIDEO_TUNER_MODULE) += tuner.o
 
 obj-$(CONFIG_V4L2_MEM2MEM_DEV) += v4l2-mem2mem.o