Re: OV5693 Kconfig missing a select VIDEO_V4L2_SUBDEV_API ?

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Hi Laurent,

On Thu, Jun 15, 2023 at 12:13:53PM +0300, Laurent Pinchart wrote:
> Hi Sakari,
> 
> On Thu, Jun 15, 2023 at 08:22:51AM +0000, sakari.ailus@xxxxxxxxxxxxxxx wrote:
> > On Thu, Jun 15, 2023 at 12:23:45AM +0300, Laurent Pinchart wrote:
> > > On Thu, Jun 15, 2023 at 12:22:58AM +0300, Laurent Pinchart wrote:
> > > > On Wed, Jun 14, 2023 at 08:30:16PM +0000, sakari.ailus@xxxxxxxxxxxxxxx wrote:
> > > > > On Wed, Jun 14, 2023 at 06:50:14PM +0200, Hans de Goede wrote:
> > > > > > On 6/14/23 18:05, sakari.ailus@xxxxxxxxxxxxxxx wrote:
> > > > > > > On Wed, Jun 14, 2023 at 05:47:01PM +0200, Hans de Goede wrote:
> > > > > > >> Hi All,
> > > > > > >>
> > > > > > >> The ov5693 driver uses v4l2_subdev_get_try_crop() /
> > > > > > >> v4l2_subdev_get_try_format() both of which are
> > > > > > >> only defined if CONFIG_VIDEO_V4L2_SUBDEV_API=y .
> > > > > > >>
> > > > > > >> Yet it does not do select VIDEO_V4L2_SUBDEV_API
> > > > > > >> in its Kconfig bits ?
> > > > > > >>
> > > > > > >> Note I've not seen any build errors because of this,
> > > > > > >> I guess we somehow end up getting away with this...
> > > > > > >>
> > > > > > >> But still I think the select should be added ?
> > > > > > > 
> > > > > > > I agree.
> > > > > > > 
> > > > > > > The reason there haven't been compile failures is that there's a vast
> > > > > > > number of sensor drivers that all select this so for a failure you'd need
> > > > > > > to select this one but none of the others.
> > > > > > > 
> > > > > > > I can send a fix.
> > > > > > 
> > > > > > Also see my follow-up email. If we're going to fix this
> > > > > > we really should fix it properly. As mentioned in
> > > > > > my folow-up email an intermediate Kconfig option
> > > > > > might be best.
> > > > > > 
> > > > > > E.g. doing:
> > > > > > 
> > > > > > grep -l v4l2_async_register_subdev drivers/media/i2c/*.c
> > > > > > 
> > > > > > And comparing that to Kconfig finds the following Kconfig
> > > > > > entries lacking a select V4L2_FWNODE / select V4l2_ASYNC
> > > > > > 
> > > > > > VIDEO_IMX208
> > > > > > VIDEO_IMX258
> > > > > > VIDEO_IMX274
> > > > > > VIDEO_IMX319
> > > > > > VIDEO_IMX355
> > > > > > VIDEO_OV6650
> > > > > > VIDEO_OV7740
> > > > > > VIDEO_OV9640
> > > > > > VIDEO_OV9650
> > > > > > 
> > > > > > and I stopped checking after the ov* drivers since I think
> > > > > > the above list makes my point.
> > > > > 
> > > > > Yeah, sometimes difficult to find errors get repeated. Luckily it's "just"
> > > > > a compilation problem.
> > > > > 
> > > > > Using V4L2 fwnode and V4L2 sub-device APIs are still unrelated as such
> > > > > although in practice they do often happen together. There are still quite a
> > > > > few sensor drivers that don't need both of them. Some can be compiled with
> > > > > VIDEO_V4L2_SUBDEV_API disabled, too, but I'm not sure how useful that
> > > > > really is. The rest are probably not usable outside a very specific scope,
> > > > > such as I²C async matching used by a handful of receiver drivers (none use
> > > > > MC, thus no sub-device API either).
> > > > > 
> > > > > Perhaps we could group these in two classes where the common class has
> > > > > V4L2_FWNODE and VIDEO_V4L2_SUBDEV_API selected? I'm not sure having an
> > > > > intermediate, somewhat obscure, option would be helpful.
> > > > > 
> > > > > Also cc Hans and Laurent.
> > > > 
> > > > I'm all for simplifying the current state and removing the need to get
> > > > every Kconfig entry right by moving the dependencies to a common
> > > > location.
> > > 
> > > Also, if sensor drivers are encouraged to use new APIs, but not all of
> > > them have been converted, I'd be fine selecting the new APIs
> > > unconditionally even if no selected sensor driver uses them.
> > 
> > There are old drivers that do not need these features and there has been
> > discussion there may be a desire to disable features to make the kernel
> > smaller (for e.g. OpenWRT), however I suspect in this case it's more likely
> > drivers that are little used.
> 
> Just to be clear, I didn't mean selecting V4L2_FWNODE, V4L2_ASYNC and
> VIDEO_V4L2_SUBDEV_API unconditionally, but when any sensor driver is
> selected. If a device has a camera, memory requirements increase
> significantly and I don't think enabling the above options will make a
> real difference.

How about something like this:

diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
index 256d55bb2b1da..8a6961aafef98 100644
--- a/drivers/media/i2c/Kconfig
+++ b/drivers/media/i2c/Kconfig
@@ -25,8 +25,14 @@ config VIDEO_IR_I2C
 # V4L2 I2C drivers that are related with Camera support
 #
 
-menu "Camera sensor devices"
-	visible if MEDIA_CAMERA_SUPPORT
+menuconfig VIDEO_CAMERA_SENSOR
+	bool "Camera sensor devices"
+	depends on MEDIA_CAMERA_SUPPORT
+	select V4L2_FWNODE
+	select VIDEO_V4L2_SUBDEV_API
+	default y
+
+if VIDEO_CAMERA_SENSOR
 
 config VIDEO_APTINA_PLL
 	tristate
@@ -797,7 +803,7 @@ config VIDEO_ST_VGXY61
 source "drivers/media/i2c/ccs/Kconfig"
 source "drivers/media/i2c/et8ek8/Kconfig"
 
-endmenu
+endif # VIDEO_CAMERA_SENSOR
 
 menu "Lens drivers"
 	visible if MEDIA_CAMERA_SUPPORT

-- 
Regards,

Sakari Ailus



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