Hi Arnd. On Fri, Apr 17, 2020 at 05:55:52PM +0200, Arnd Bergmann 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. > > This is the same way that the backlight is already treated for the DRM > subsystem. I am not happy with the direction of this patch. It is not easy to understand that one has to enable backlight to be allowed to select a display or an fbdev driver. How about somthing like this: config BACKLIGHT_CLASS_DEVICE tristate # Will enable backlight module # Has no dependencies config BACKLIGHT bool "Backlight drivers" # Will make the backlight drivers visible - a visibility option # only if BACKLIGHT config BACKLIGHT_ATMEL_LCDC ... config BACKLIGHT_EP93XX endif All drivers outside video/backlight/ can then select BACKLIGHT_CLASS_DEVICE to get the backlight core module. Or in other words BACKLIGHT_CLASS_DEVICE is used as a sort of library symbol that gices us access to backlight functionality. I tried something like this some time ago - but it did not work out for me. But maybe I just missed something obviously in the maze of Kconfig. Loking at your patch it is obviously that the approach I suggest above would require all relevant drivers to explicit add a select BACKLIGHT_CLASS_DEVICE. But that is not a bad thing IMO. Sam > > Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx> > --- > 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 48efa7a047f3..f5751b5b0e88 100644 > --- a/drivers/auxdisplay/Kconfig > +++ b/drivers/auxdisplay/Kconfig > @@ -144,6 +144,7 @@ config IMG_ASCII_LCD > config HT16K33 > tristate "Holtek Ht16K33 LED controller with keyscan" > depends on FB && OF && 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 cbd46c1c5bf7..a1c6677c7043 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 bcf7834dbdbf..47e1b65276f4 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 > @@ -861,6 +861,7 @@ 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 > @@ -914,6 +915,7 @@ 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. > @@ -961,6 +963,7 @@ 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. > @@ -1232,6 +1235,7 @@ 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. > @@ -1263,6 +1267,7 @@ 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. > @@ -1312,6 +1317,7 @@ 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 > @@ -1855,6 +1861,7 @@ 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 > @@ -2183,7 +2190,7 @@ 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 > @@ -2250,6 +2257,7 @@ config FB_SSD1307 > depends on FB && I2C > depends on OF > depends on GPIOLIB || COMPILE_TEST > + depends on BACKLIGHT_CLASS_DEVICE > select FB_SYS_FOPS > select FB_SYS_FILLRECT > select FB_SYS_COPYAREA > -- > 2.26.0 > > _______________________________________________ > dri-devel mailing list > dri-devel@xxxxxxxxxxxxxxxxxxxxx > https://lists.freedesktop.org/mailman/listinfo/dri-devel _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
