[PATCH 1/3] fbdev: rework FB_DDC dependencies

[PATCH 1/3] fbdev: rework FB_DDC dependencies

[Arnd Bergmann]

From: Arnd Bergmann <arnd@arndb.de>

Selecting FB_DDC currently turns on CONFIG_I2C implicitly,
which is often not desired and can lead to circular dependencies.

Change this to a 'depends on' and change all drivers that
rely on FB_DDC to have an appropriate I2C dependency as well.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/video/fbdev/Kconfig | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/drivers/video/fbdev/Kconfig b/drivers/video/fbdev/Kconfig
index 6ed5e608dd04..c187a93c9a16 100644
--- a/drivers/video/fbdev/Kconfig
+++ b/drivers/video/fbdev/Kconfig
@@ -62,9 +62,8 @@ config FIRMWARE_EDID
 
 config FB_DDC
 	tristate
-	depends on FB
+	depends on FB && I2C
 	select I2C_ALGOBIT
-	select I2C
 
 config FB_BOOT_VESA_SUPPORT
 	bool
@@ -356,6 +355,7 @@ config FB_CYBER2000
 config FB_CYBER2000_DDC
 	bool "DDC for CyberPro support"
 	depends on FB_CYBER2000
+	depends on I2C=y || I2C=FB_CYBER2000
 	select FB_DDC
 	default y
 	help
@@ -894,6 +894,7 @@ config FB_NVIDIA
 config FB_NVIDIA_I2C
 	bool "Enable DDC Support"
 	depends on FB_NVIDIA
+	depends on I2C=y || I2C=FB_NVIDIA
 	select FB_DDC
 	help
 	  This enables I2C support for nVidia Chipsets.  This is used
@@ -940,6 +941,7 @@ config FB_RIVA
 config FB_RIVA_I2C
 	bool "Enable DDC Support"
 	depends on FB_RIVA
+	depends on I2C=y || I2C=FB_RIVA
 	select FB_DDC
 	help
 	  This enables I2C support for nVidia Chipsets.  This is used
@@ -967,7 +969,7 @@ config FB_RIVA_BACKLIGHT
 
 config FB_I740
 	tristate "Intel740 support"
-	depends on FB && PCI
+	depends on FB && PCI && I2C
 	select FB_MODE_HELPERS
 	select FB_CFB_FILLRECT
 	select FB_CFB_COPYAREA
@@ -1021,6 +1023,7 @@ config FB_I810_GTF
 config FB_I810_I2C
 	bool "Enable DDC Support"
 	depends on FB_I810 && FB_I810_GTF
+	depends on I2C=y || I2C=FB_I810
 	select FB_DDC
 	help
 	  Add DDC/I2C support for i810fb.  This will allow the driver to get
@@ -1076,6 +1079,7 @@ config FB_INTEL_DEBUG
 config FB_INTEL_I2C
 	bool "DDC/I2C for Intel framebuffer support"
 	depends on FB_INTEL
+	depends on I2C=y || I2C=FB_INTEL
 	select FB_DDC
 	default y
 	help
@@ -1155,6 +1159,7 @@ config FB_MATROX_G
 config FB_MATROX_I2C
 	tristate "Matrox I2C support"
 	depends on FB_MATROX
+	depends on I2C=y || I2C=FB_MATROX
 	select FB_DDC
 	help
 	  This drivers creates I2C buses which are needed for accessing the
@@ -1220,6 +1225,7 @@ config FB_RADEON
 config FB_RADEON_I2C
 	bool "DDC/I2C for ATI Radeon support"
 	depends on FB_RADEON
+	depends on I2C=y || I2C=FB_RADEON
 	select FB_DDC
 	default y
 	help
@@ -1329,6 +1335,7 @@ config FB_S3
 config FB_S3_DDC
 	bool "DDC for S3 support"
 	depends on FB_S3
+	depends on I2C=y || I2C=FB_S3
 	select FB_DDC
 	default y
 	help
@@ -1354,6 +1361,7 @@ config FB_SAVAGE
 config FB_SAVAGE_I2C
 	bool "Enable DDC2 Support"
 	depends on FB_SAVAGE
+	depends on I2C=y || I2C=FB_SAVAGE
 	select FB_DDC
 	help
 	  This enables I2C support for S3 Savage Chipsets.  This is used
@@ -1493,6 +1501,7 @@ config FB_3DFX_ACCEL
 config FB_3DFX_I2C
 	bool "Enable DDC/I2C support"
 	depends on FB_3DFX
+	depends on I2C=y || I2C=FB_3DFX
 	select FB_DDC
 	default y
 	help
@@ -1532,7 +1541,7 @@ config FB_VT8623
 
 config FB_TRIDENT
 	tristate "Trident/CyberXXX/CyberBlade support"
-	depends on FB && PCI
+	depends on FB && PCI && I2C
 	select FB_CFB_FILLRECT
 	select FB_CFB_COPYAREA
 	select FB_CFB_IMAGEBLIT
-- 
2.29.2

[PATCH 2/3] fbdev: rework backlight dependencies

[Arnd Bergmann]

From: Arnd Bergmann <arnd@arndb.de>

Rather than having CONFIG_FB_BACKLIGHT select CONFIG_BACKLIGHT_CLASS_DEVICE,
make any driver that needs it have a dependency on the class device
being available, to prevent circular dependencies.

This is the same way that the backlight is already treated for the DRM
subsystem.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/auxdisplay/Kconfig        |  1 +
 drivers/macintosh/Kconfig         |  1 +
 drivers/staging/fbtft/Kconfig     |  1 +
 drivers/staging/olpc_dcon/Kconfig |  2 +-
 drivers/video/fbdev/Kconfig       | 14 +++++++++++---
 5 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/drivers/auxdisplay/Kconfig b/drivers/auxdisplay/Kconfig
index 64012cda4d12..356afb6a569d 100644
--- a/drivers/auxdisplay/Kconfig
+++ b/drivers/auxdisplay/Kconfig
@@ -170,6 +170,7 @@ config IMG_ASCII_LCD
 config HT16K33
 	tristate "Holtek Ht16K33 LED controller with keyscan"
 	depends on FB && I2C && INPUT
+	depends on BACKLIGHT_CLASS_DEVICE
 	select FB_SYS_FOPS
 	select FB_SYS_FILLRECT
 	select FB_SYS_COPYAREA
diff --git a/drivers/macintosh/Kconfig b/drivers/macintosh/Kconfig
index 5cdc361da37c..cb0fbdf8ff7f 100644
--- a/drivers/macintosh/Kconfig
+++ b/drivers/macintosh/Kconfig
@@ -113,6 +113,7 @@ config PMAC_MEDIABAY
 config PMAC_BACKLIGHT
 	bool "Backlight control for LCD screens"
 	depends on PPC_PMAC && ADB_PMU && FB = y && (BROKEN || !PPC64)
+	depends on BACKLIGHT_CLASS_DEVICE
 	select FB_BACKLIGHT
 	help
 	  Say Y here to enable Macintosh specific extensions of the generic
diff --git a/drivers/staging/fbtft/Kconfig b/drivers/staging/fbtft/Kconfig
index dad1ddcd7b0c..c4f2f01cd798 100644
--- a/drivers/staging/fbtft/Kconfig
+++ b/drivers/staging/fbtft/Kconfig
@@ -3,6 +3,7 @@ menuconfig FB_TFT
 	tristate "Support for small TFT LCD display modules"
 	depends on FB && SPI
 	depends on GPIOLIB || COMPILE_TEST
+	depends on BACKLIGHT_CLASS_DEVICE
 	select FB_SYS_FILLRECT
 	select FB_SYS_COPYAREA
 	select FB_SYS_IMAGEBLIT
diff --git a/drivers/staging/olpc_dcon/Kconfig b/drivers/staging/olpc_dcon/Kconfig
index d1a0dea09ef0..a9f36538d7ab 100644
--- a/drivers/staging/olpc_dcon/Kconfig
+++ b/drivers/staging/olpc_dcon/Kconfig
@@ -4,7 +4,7 @@ config FB_OLPC_DCON
 	depends on OLPC && FB
 	depends on I2C
 	depends on GPIO_CS5535 && ACPI
-	select BACKLIGHT_CLASS_DEVICE
+	depends on BACKLIGHT_CLASS_DEVICE
 	help
 	  In order to support very low power operation, the XO laptop uses a
 	  secondary Display CONtroller, or DCON.  This secondary controller
diff --git a/drivers/video/fbdev/Kconfig b/drivers/video/fbdev/Kconfig
index c187a93c9a16..3ad499433726 100644
--- a/drivers/video/fbdev/Kconfig
+++ b/drivers/video/fbdev/Kconfig
@@ -186,7 +186,7 @@ config FB_MACMODES
 config FB_BACKLIGHT
 	tristate
 	depends on FB
-	select BACKLIGHT_CLASS_DEVICE
+	depends on BACKLIGHT_CLASS_DEVICE
 
 config FB_MODE_HELPERS
 	bool "Enable Video Mode Handling Helpers"
@@ -275,12 +275,12 @@ config FB_ARMCLCD
 	tristate "ARM PrimeCell PL110 support"
 	depends on ARM || ARM64 || COMPILE_TEST
 	depends on FB && ARM_AMBA && HAS_IOMEM
+	depends on BACKLIGHT_CLASS_DEVICE || !OF
 	select FB_CFB_FILLRECT
 	select FB_CFB_COPYAREA
 	select FB_CFB_IMAGEBLIT
 	select FB_MODE_HELPERS if OF
 	select VIDEOMODE_HELPERS if OF
-	select BACKLIGHT_CLASS_DEVICE if OF
 	help
 	  This framebuffer device driver is for the ARM PrimeCell PL110
 	  Colour LCD controller.  ARM PrimeCells provide the building
@@ -863,6 +863,7 @@ config FB_ATMEL
 	tristate "AT91 LCD Controller support"
 	depends on FB && OF && HAVE_CLK && HAS_IOMEM
 	depends on HAVE_FB_ATMEL || COMPILE_TEST
+	depends on BACKLIGHT_CLASS_DEVICE
 	select FB_BACKLIGHT
 	select FB_CFB_FILLRECT
 	select FB_CFB_COPYAREA
@@ -916,6 +917,7 @@ config FB_NVIDIA_DEBUG
 config FB_NVIDIA_BACKLIGHT
 	bool "Support for backlight control"
 	depends on FB_NVIDIA
+	depends on BACKLIGHT_CLASS_DEVICE=y || BACKLIGHT_CLASS_DEVICE=FB_NVIDIA
 	default y
 	help
 	  Say Y here if you want to control the backlight of your display.
@@ -963,6 +965,7 @@ config FB_RIVA_DEBUG
 config FB_RIVA_BACKLIGHT
 	bool "Support for backlight control"
 	depends on FB_RIVA
+	depends on BACKLIGHT_CLASS_DEVICE=y || BACKLIGHT_CLASS_DEVICE=FB_RIVA
 	default y
 	help
 	  Say Y here if you want to control the backlight of your display.
@@ -1234,6 +1237,7 @@ config FB_RADEON_I2C
 config FB_RADEON_BACKLIGHT
 	bool "Support for backlight control"
 	depends on FB_RADEON
+	depends on BACKLIGHT_CLASS_DEVICE=y || BACKLIGHT_CLASS_DEVICE=FB_RADEON
 	default y
 	help
 	  Say Y here if you want to control the backlight of your display.
@@ -1265,6 +1269,7 @@ config FB_ATY128
 config FB_ATY128_BACKLIGHT
 	bool "Support for backlight control"
 	depends on FB_ATY128
+	depends on BACKLIGHT_CLASS_DEVICE=y || BACKLIGHT_CLASS_DEVICE=FB_ATY128
 	default y
 	help
 	  Say Y here if you want to control the backlight of your display.
@@ -1314,6 +1319,7 @@ config FB_ATY_GX
 
 config FB_ATY_BACKLIGHT
 	bool "Support for backlight control"
+	depends on BACKLIGHT_CLASS_DEVICE=y || BACKLIGHT_CLASS_DEVICE=FB_ATY
 	depends on FB_ATY
 	default y
 	help
@@ -1838,6 +1844,7 @@ config FB_SH_MOBILE_LCDC
 	tristate "SuperH Mobile LCDC framebuffer support"
 	depends on FB && HAVE_CLK && HAS_IOMEM
 	depends on SUPERH || ARCH_RENESAS || COMPILE_TEST
+	depends on BACKLIGHT_CLASS_DEVICE
 	select FB_SYS_FILLRECT
 	select FB_SYS_COPYAREA
 	select FB_SYS_IMAGEBLIT
@@ -2166,7 +2173,7 @@ config FB_PRE_INIT_FB
 config FB_MX3
 	tristate "MX3 Framebuffer support"
 	depends on FB && MX3_IPU
-	select BACKLIGHT_CLASS_DEVICE
+	depends on BACKLIGHT_CLASS_DEVICE
 	select FB_CFB_FILLRECT
 	select FB_CFB_COPYAREA
 	select FB_CFB_IMAGEBLIT
@@ -2222,6 +2229,7 @@ config FB_SSD1307
 	tristate "Solomon SSD1307 framebuffer support"
 	depends on FB && I2C
 	depends on GPIOLIB || COMPILE_TEST
+	depends on BACKLIGHT_CLASS_DEVICE
 	select FB_SYS_FOPS
 	select FB_SYS_FILLRECT
 	select FB_SYS_COPYAREA
-- 
2.29.2

[PATCH 3/3] [v2] i915: fix backlight configuration issue

[Arnd Bergmann]

From: Arnd Bergmann <arnd@arndb.de>

The i915 driver can use the backlight subsystem as an option, and usually
selects it when CONFIG_ACPI is set. However it is possible to configure
a kernel with modular backlight classdev support and a built-in i915
driver, which leads to a linker error:

drivers/gpu/drm/i915/display/intel_panel.o: In function `intel_backlight_device_register':
intel_panel.c:(.text+0x2f58): undefined reference to `backlight_device_register'
drivers/gpu/drm/i915/display/intel_panel.o: In function `intel_backlight_device_unregister':
intel_panel.c:(.text+0x2fe4): undefined reference to `backlight_device_unregister'

Change i915 to just 'depends on' for both BACKLIGHT_CLASS_DEVICE
and ACPI_VIDEO, which avoids a lot of the problems.

Link: https://lore.kernel.org/all/20200108140227.3976563-1-arnd@arndb.de/
Link: https://lore.kernel.org/all/20200417155553.675905-1-arnd@arndb.de/
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
This change depends on cleaning up drivers/video/fbdev to no longer
'select' I2C and BACKLIGHT_CLASS_DEVICE, otherwise it causes
dependency loops.
---
 drivers/gpu/drm/i915/Kconfig | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/Kconfig b/drivers/gpu/drm/i915/Kconfig
index 84b6fc70cbf5..f427e6d50d9b 100644
--- a/drivers/gpu/drm/i915/Kconfig
+++ b/drivers/gpu/drm/i915/Kconfig
@@ -3,6 +3,8 @@ config DRM_I915
 	tristate "Intel 8xx/9xx/G3x/G4x/HD Graphics"
 	depends on DRM
 	depends on X86 && PCI
+	depends on ACPI_VIDEO || !ACPI
+	depends on BACKLIGHT_CLASS_DEVICE || !BACKLIGHT_CLASS_DEVICE
 	select INTEL_GTT
 	select INTERVAL_TREE
 	# we need shmfs for the swappable backing store, and in particular
@@ -16,10 +18,6 @@ config DRM_I915
 	select IRQ_WORK
 	# i915 depends on ACPI_VIDEO when ACPI is enabled
 	# but for select to work, need to select ACPI_VIDEO's dependencies, ick
-	select BACKLIGHT_CLASS_DEVICE if ACPI
-	select INPUT if ACPI
-	select ACPI_VIDEO if ACPI
-	select ACPI_BUTTON if ACPI
 	select SYNC_FILE
 	select IOSF_MBI
 	select CRC32
-- 
2.29.2

Re: [PATCH 2/3] fbdev: rework backlight dependencies

[Miguel Ojeda]

On Wed, Oct 27, 2021 at 3:28 PM Arnd Bergmann <arnd@kernel.org> wrote:
>
> Rather than having CONFIG_FB_BACKLIGHT select CONFIG_BACKLIGHT_CLASS_DEVICE,
> make any driver that needs it have a dependency on the class device
> being available, to prevent circular dependencies.

Acked-by: Miguel Ojeda <ojeda@kernel.org>

Cheers,
Miguel

Re: [PATCH 3/3] [v2] i915: fix backlight configuration issue

[Jani Nikula]

On Wed, 27 Oct 2021, Arnd Bergmann <arnd@kernel.org> wrote:
> From: Arnd Bergmann <arnd@arndb.de>
>
> The i915 driver can use the backlight subsystem as an option, and usually
> selects it when CONFIG_ACPI is set. However it is possible to configure
> a kernel with modular backlight classdev support and a built-in i915
> driver, which leads to a linker error:
>
> drivers/gpu/drm/i915/display/intel_panel.o: In function `intel_backlight_device_register':
> intel_panel.c:(.text+0x2f58): undefined reference to `backlight_device_register'
> drivers/gpu/drm/i915/display/intel_panel.o: In function `intel_backlight_device_unregister':
> intel_panel.c:(.text+0x2fe4): undefined reference to `backlight_device_unregister'
>
> Change i915 to just 'depends on' for both BACKLIGHT_CLASS_DEVICE
> and ACPI_VIDEO, which avoids a lot of the problems.
>
> Link: https://lore.kernel.org/all/20200108140227.3976563-1-arnd@arndb.de/
> Link: https://lore.kernel.org/all/20200417155553.675905-1-arnd@arndb.de/
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> This change depends on cleaning up drivers/video/fbdev to no longer
> 'select' I2C and BACKLIGHT_CLASS_DEVICE, otherwise it causes
> dependency loops.
> ---
>  drivers/gpu/drm/i915/Kconfig | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/Kconfig b/drivers/gpu/drm/i915/Kconfig
> index 84b6fc70cbf5..f427e6d50d9b 100644
> --- a/drivers/gpu/drm/i915/Kconfig
> +++ b/drivers/gpu/drm/i915/Kconfig
> @@ -3,6 +3,8 @@ config DRM_I915
>  	tristate "Intel 8xx/9xx/G3x/G4x/HD Graphics"
>  	depends on DRM
>  	depends on X86 && PCI
> +	depends on ACPI_VIDEO || !ACPI
> +	depends on BACKLIGHT_CLASS_DEVICE || !BACKLIGHT_CLASS_DEVICE
>  	select INTEL_GTT
>  	select INTERVAL_TREE
>  	# we need shmfs for the swappable backing store, and in particular
> @@ -16,10 +18,6 @@ config DRM_I915
>  	select IRQ_WORK
>  	# i915 depends on ACPI_VIDEO when ACPI is enabled
>  	# but for select to work, need to select ACPI_VIDEO's dependencies, ick

The comment needs updating as well.

Other than that,

Acked-by: Jani Nikula <jani.nikula@intel.com>

on the series.

> -	select BACKLIGHT_CLASS_DEVICE if ACPI
> -	select INPUT if ACPI
> -	select ACPI_VIDEO if ACPI
> -	select ACPI_BUTTON if ACPI
>  	select SYNC_FILE
>  	select IOSF_MBI
>  	select CRC32

-- 
Jani Nikula, Intel Open Source Graphics Center

Re: [PATCH 3/3] [v2] i915: fix backlight configuration issue

[Arnd Bergmann]

On Wed, Oct 27, 2021 at 3:41 PM Jani Nikula <jani.nikula@linux.intel.com> wrote:
> > @@ -16,10 +18,6 @@ config DRM_I915
> >       select IRQ_WORK
> >       # i915 depends on ACPI_VIDEO when ACPI is enabled
> >       # but for select to work, need to select ACPI_VIDEO's dependencies, ick
>
> The comment needs updating as well.

Right, I've removed that comment now.

> Other than that,
>
> Acked-by: Jani Nikula <jani.nikula@intel.com>
>
> on the series.

Thanks!

         Arnd

Re: [PATCH 1/3] fbdev: rework FB_DDC dependencies

[Andy Shevchenko]

On Wed, Oct 27, 2021 at 03:27:12PM +0200, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> Selecting FB_DDC currently turns on CONFIG_I2C implicitly,
> which is often not desired and can lead to circular dependencies.
> 
> Change this to a 'depends on' and change all drivers that
> rely on FB_DDC to have an appropriate I2C dependency as well.

No objections from me.
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>  drivers/video/fbdev/Kconfig | 17 +++++++++++++----
>  1 file changed, 13 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/video/fbdev/Kconfig b/drivers/video/fbdev/Kconfig
> index 6ed5e608dd04..c187a93c9a16 100644
> --- a/drivers/video/fbdev/Kconfig
> +++ b/drivers/video/fbdev/Kconfig
> @@ -62,9 +62,8 @@ config FIRMWARE_EDID
>  
>  config FB_DDC
>  	tristate
> -	depends on FB
> +	depends on FB && I2C
>  	select I2C_ALGOBIT
> -	select I2C
>  
>  config FB_BOOT_VESA_SUPPORT
>  	bool
> @@ -356,6 +355,7 @@ config FB_CYBER2000
>  config FB_CYBER2000_DDC
>  	bool "DDC for CyberPro support"
>  	depends on FB_CYBER2000
> +	depends on I2C=y || I2C=FB_CYBER2000
>  	select FB_DDC
>  	default y
>  	help
> @@ -894,6 +894,7 @@ config FB_NVIDIA
>  config FB_NVIDIA_I2C
>  	bool "Enable DDC Support"
>  	depends on FB_NVIDIA
> +	depends on I2C=y || I2C=FB_NVIDIA
>  	select FB_DDC
>  	help
>  	  This enables I2C support for nVidia Chipsets.  This is used
> @@ -940,6 +941,7 @@ config FB_RIVA
>  config FB_RIVA_I2C
>  	bool "Enable DDC Support"
>  	depends on FB_RIVA
> +	depends on I2C=y || I2C=FB_RIVA
>  	select FB_DDC
>  	help
>  	  This enables I2C support for nVidia Chipsets.  This is used
> @@ -967,7 +969,7 @@ config FB_RIVA_BACKLIGHT
>  
>  config FB_I740
>  	tristate "Intel740 support"
> -	depends on FB && PCI
> +	depends on FB && PCI && I2C
>  	select FB_MODE_HELPERS
>  	select FB_CFB_FILLRECT
>  	select FB_CFB_COPYAREA
> @@ -1021,6 +1023,7 @@ config FB_I810_GTF
>  config FB_I810_I2C
>  	bool "Enable DDC Support"
>  	depends on FB_I810 && FB_I810_GTF
> +	depends on I2C=y || I2C=FB_I810
>  	select FB_DDC
>  	help
>  	  Add DDC/I2C support for i810fb.  This will allow the driver to get
> @@ -1076,6 +1079,7 @@ config FB_INTEL_DEBUG
>  config FB_INTEL_I2C
>  	bool "DDC/I2C for Intel framebuffer support"
>  	depends on FB_INTEL
> +	depends on I2C=y || I2C=FB_INTEL
>  	select FB_DDC
>  	default y
>  	help
> @@ -1155,6 +1159,7 @@ config FB_MATROX_G
>  config FB_MATROX_I2C
>  	tristate "Matrox I2C support"
>  	depends on FB_MATROX
> +	depends on I2C=y || I2C=FB_MATROX
>  	select FB_DDC
>  	help
>  	  This drivers creates I2C buses which are needed for accessing the
> @@ -1220,6 +1225,7 @@ config FB_RADEON
>  config FB_RADEON_I2C
>  	bool "DDC/I2C for ATI Radeon support"
>  	depends on FB_RADEON
> +	depends on I2C=y || I2C=FB_RADEON
>  	select FB_DDC
>  	default y
>  	help
> @@ -1329,6 +1335,7 @@ config FB_S3
>  config FB_S3_DDC
>  	bool "DDC for S3 support"
>  	depends on FB_S3
> +	depends on I2C=y || I2C=FB_S3
>  	select FB_DDC
>  	default y
>  	help
> @@ -1354,6 +1361,7 @@ config FB_SAVAGE
>  config FB_SAVAGE_I2C
>  	bool "Enable DDC2 Support"
>  	depends on FB_SAVAGE
> +	depends on I2C=y || I2C=FB_SAVAGE
>  	select FB_DDC
>  	help
>  	  This enables I2C support for S3 Savage Chipsets.  This is used
> @@ -1493,6 +1501,7 @@ config FB_3DFX_ACCEL
>  config FB_3DFX_I2C
>  	bool "Enable DDC/I2C support"
>  	depends on FB_3DFX
> +	depends on I2C=y || I2C=FB_3DFX
>  	select FB_DDC
>  	default y
>  	help
> @@ -1532,7 +1541,7 @@ config FB_VT8623
>  
>  config FB_TRIDENT
>  	tristate "Trident/CyberXXX/CyberBlade support"
> -	depends on FB && PCI
> +	depends on FB && PCI && I2C
>  	select FB_CFB_FILLRECT
>  	select FB_CFB_COPYAREA
>  	select FB_CFB_IMAGEBLIT
> -- 
> 2.29.2
> 

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH 2/3] fbdev: rework backlight dependencies

[Randy Dunlap]

On 10/27/21 6:27 AM, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> Rather than having CONFIG_FB_BACKLIGHT select CONFIG_BACKLIGHT_CLASS_DEVICE,
> make any driver that needs it have a dependency on the class device
> being available, to prevent circular dependencies.
> 
> This is the same way that the backlight is already treated for the DRM
> subsystem.
> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>   drivers/auxdisplay/Kconfig        |  1 +
>   drivers/macintosh/Kconfig         |  1 +
>   drivers/staging/fbtft/Kconfig     |  1 +
>   drivers/staging/olpc_dcon/Kconfig |  2 +-
>   drivers/video/fbdev/Kconfig       | 14 +++++++++++---
>   5 files changed, 15 insertions(+), 4 deletions(-)

Acked-by: Randy Dunlap <rdunlap@infraded.org>

Thanks.

-- 
~Randy