* [PATCH 1/3] drm/omap: displays: panel-dpi: add backlight dependency @ 2017-04-19 17:59 Arnd Bergmann 2017-04-19 17:59 ` [PATCH 2/3] drm/panel: S6E3HA2 needs backlight code Arnd Bergmann 2017-04-19 20:21 ` [PATCH 1/3] drm/omap: displays: panel-dpi: add backlight dependency Laurent Pinchart 0 siblings, 2 replies; 8+ messages in thread From: Arnd Bergmann @ 2017-04-19 17:59 UTC (permalink / raw) To: Tomi Valkeinen, David Airlie Cc: Arnd Bergmann, Laurent Pinchart, dri-devel, linux-kernel The panel driver gained support for backlight but fails to link now when that is disabled: drivers/gpu/drm/omapdrm/displays/panel-dpi.o: In function `panel_dpi_probe_of': panel-dpi.c:(.text.panel_dpi_probe_of+0xe8): undefined reference to `of_find_backlight_by_node' This adds a dependency like we have for the other panel drivers. Fixes: 39135a305a0f ("drm/omap: displays: panel-dpi: Support for handling backlight devices") Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- drivers/gpu/drm/omapdrm/displays/Kconfig | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/gpu/drm/omapdrm/displays/Kconfig b/drivers/gpu/drm/omapdrm/displays/Kconfig index c226da145fb3..a349cb61961e 100644 --- a/drivers/gpu/drm/omapdrm/displays/Kconfig +++ b/drivers/gpu/drm/omapdrm/displays/Kconfig @@ -35,6 +35,7 @@ config DRM_OMAP_CONNECTOR_ANALOG_TV config DRM_OMAP_PANEL_DPI tristate "Generic DPI panel" + depends on BACKLIGHT_CLASS_DEVICE help Driver for generic DPI panels. -- 2.9.0 ^ permalink raw reply related [flat|nested] 8+ messages in thread
* [PATCH 2/3] drm/panel: S6E3HA2 needs backlight code 2017-04-19 17:59 [PATCH 1/3] drm/omap: displays: panel-dpi: add backlight dependency Arnd Bergmann @ 2017-04-19 17:59 ` Arnd Bergmann 2017-04-19 18:03 ` [PATCH 3/3] drm/panel: add backlight dependency for sitronix-st7789v Arnd Bergmann 2017-06-14 18:13 ` [PATCH 2/3] drm/panel: S6E3HA2 needs backlight code Thierry Reding 2017-04-19 20:21 ` [PATCH 1/3] drm/omap: displays: panel-dpi: add backlight dependency Laurent Pinchart 1 sibling, 2 replies; 8+ messages in thread From: Arnd Bergmann @ 2017-04-19 17:59 UTC (permalink / raw) To: Thierry Reding, David Airlie Cc: Arnd Bergmann, Vinay Simha BN, Laurent Pinchart, Hoegeun Kwon, dri-devel, linux-kernel The new S6E3HA2 driver fails to link when backlight is disabled: ERROR: "backlight_device_register" [drivers/gpu/drm/panel/panel-samsung-s6e3ha2.ko] undefined! ERROR: "backlight_device_unregister" [drivers/gpu/drm/panel/panel-samsung-s6e3ha2.ko] undefined! This adds a Kconfig dependency like we have it for some other panel drivers. Fixes: ed29f9426d9b ("drm/panel: Add support for S6E3HA2 panel driver on TM2 board") Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- drivers/gpu/drm/panel/Kconfig | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig index 3e29a9903303..6eb9774284df 100644 --- a/drivers/gpu/drm/panel/Kconfig +++ b/drivers/gpu/drm/panel/Kconfig @@ -66,6 +66,7 @@ config DRM_PANEL_SAMSUNG_S6E3HA2 tristate "Samsung S6E3HA2 DSI video mode panel" depends on OF depends on DRM_MIPI_DSI + depends on BACKLIGHT_CLASS_DEVICE select VIDEOMODE_HELPERS config DRM_PANEL_SAMSUNG_S6E8AA0 -- 2.9.0 ^ permalink raw reply related [flat|nested] 8+ messages in thread
* [PATCH 3/3] drm/panel: add backlight dependency for sitronix-st7789v 2017-04-19 17:59 ` [PATCH 2/3] drm/panel: S6E3HA2 needs backlight code Arnd Bergmann @ 2017-04-19 18:03 ` Arnd Bergmann 2017-06-14 18:13 ` Thierry Reding 2017-06-14 18:13 ` [PATCH 2/3] drm/panel: S6E3HA2 needs backlight code Thierry Reding 1 sibling, 1 reply; 8+ messages in thread From: Arnd Bergmann @ 2017-04-19 18:03 UTC (permalink / raw) To: Thierry Reding, David Airlie Cc: Arnd Bergmann, Donghwa Lee, Hoegeun Kwon, Laurent Pinchart, Maxime Ripard, dri-devel, linux-kernel Without the dependency, we run into a link error: drivers/gpu/drm/panel/panel-sitronix-st7789v.o: In function `st7789v_probe': panel-sitronix-st7789v.c:(.text.st7789v_probe+0xc0): undefined reference to `of_find_backlight_by_node' Fixes: 7142afb3a186 ("drm/panel: Add driver for sitronix ST7789V LCD controller") Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- drivers/gpu/drm/panel/Kconfig | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig index 6eb9774284df..04d068177e16 100644 --- a/drivers/gpu/drm/panel/Kconfig +++ b/drivers/gpu/drm/panel/Kconfig @@ -101,6 +101,7 @@ config DRM_PANEL_SHARP_LS043T1LE01 config DRM_PANEL_SITRONIX_ST7789V tristate "Sitronix ST7789V panel" depends on OF && SPI + depends on BACKLIGHT_CLASS_DEVICE help Say Y here if you want to enable support for the Sitronix ST7789V controller for 240x320 LCD panels -- 2.9.0 ^ permalink raw reply related [flat|nested] 8+ messages in thread
* Re: [PATCH 3/3] drm/panel: add backlight dependency for sitronix-st7789v 2017-04-19 18:03 ` [PATCH 3/3] drm/panel: add backlight dependency for sitronix-st7789v Arnd Bergmann @ 2017-06-14 18:13 ` Thierry Reding 0 siblings, 0 replies; 8+ messages in thread From: Thierry Reding @ 2017-06-14 18:13 UTC (permalink / raw) To: Arnd Bergmann Cc: David Airlie, Donghwa Lee, Hoegeun Kwon, Laurent Pinchart, Maxime Ripard, dri-devel, linux-kernel [-- Attachment #1: Type: text/plain, Size: 575 bytes --] On Wed, Apr 19, 2017 at 08:03:08PM +0200, Arnd Bergmann wrote: > Without the dependency, we run into a link error: > > drivers/gpu/drm/panel/panel-sitronix-st7789v.o: In function `st7789v_probe': > panel-sitronix-st7789v.c:(.text.st7789v_probe+0xc0): undefined reference to `of_find_backlight_by_node' > > Fixes: 7142afb3a186 ("drm/panel: Add driver for sitronix ST7789V LCD controller") > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > --- > drivers/gpu/drm/panel/Kconfig | 1 + > 1 file changed, 1 insertion(+) Applied to drm-misc-next, thanks. Thierry [-- Attachment #2: signature.asc --] [-- Type: application/pgp-signature, Size: 833 bytes --] ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH 2/3] drm/panel: S6E3HA2 needs backlight code 2017-04-19 17:59 ` [PATCH 2/3] drm/panel: S6E3HA2 needs backlight code Arnd Bergmann 2017-04-19 18:03 ` [PATCH 3/3] drm/panel: add backlight dependency for sitronix-st7789v Arnd Bergmann @ 2017-06-14 18:13 ` Thierry Reding 1 sibling, 0 replies; 8+ messages in thread From: Thierry Reding @ 2017-06-14 18:13 UTC (permalink / raw) To: Arnd Bergmann Cc: David Airlie, Vinay Simha BN, Laurent Pinchart, Hoegeun Kwon, dri-devel, linux-kernel [-- Attachment #1: Type: text/plain, Size: 688 bytes --] On Wed, Apr 19, 2017 at 07:59:18PM +0200, Arnd Bergmann wrote: > The new S6E3HA2 driver fails to link when backlight is disabled: > > ERROR: "backlight_device_register" [drivers/gpu/drm/panel/panel-samsung-s6e3ha2.ko] undefined! > ERROR: "backlight_device_unregister" [drivers/gpu/drm/panel/panel-samsung-s6e3ha2.ko] undefined! > > This adds a Kconfig dependency like we have it for some other panel drivers. > > Fixes: ed29f9426d9b ("drm/panel: Add support for S6E3HA2 panel driver on TM2 board") > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > --- > drivers/gpu/drm/panel/Kconfig | 1 + > 1 file changed, 1 insertion(+) Applied to drm-misc-next, thanks. Thierry [-- Attachment #2: signature.asc --] [-- Type: application/pgp-signature, Size: 833 bytes --] ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH 1/3] drm/omap: displays: panel-dpi: add backlight dependency 2017-04-19 17:59 [PATCH 1/3] drm/omap: displays: panel-dpi: add backlight dependency Arnd Bergmann 2017-04-19 17:59 ` [PATCH 2/3] drm/panel: S6E3HA2 needs backlight code Arnd Bergmann @ 2017-04-19 20:21 ` Laurent Pinchart 2017-04-19 20:39 ` Arnd Bergmann 1 sibling, 1 reply; 8+ messages in thread From: Laurent Pinchart @ 2017-04-19 20:21 UTC (permalink / raw) To: Arnd Bergmann; +Cc: Tomi Valkeinen, David Airlie, dri-devel, linux-kernel Hi Arnd, Thank you for the patch. On Wednesday 19 Apr 2017 19:59:17 Arnd Bergmann wrote: > The panel driver gained support for backlight but fails to link now > when that is disabled: > > drivers/gpu/drm/omapdrm/displays/panel-dpi.o: In function > `panel_dpi_probe_of': panel-dpi.c:(.text.panel_dpi_probe_of+0xe8): > undefined reference to `of_find_backlight_by_node' > > This adds a dependency like we have for the other panel drivers. I believe the dependency should be made optional. DPI panels that don't need backlight control should be supported by a kernel that has backlight support compiled out. How about something like >From 07a98ab23b2080c79abbf8b5e7479123c50e6be7 Mon Sep 17 00:00:00 2001 From: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Date: Wed, 19 Apr 2017 23:13:43 +0300 Subject: [PATCH] backlight: Define API stub when backlight support is disabled The of_find_backlight_by_node() function has a stubbed when CONFIG_OF is disabled, but drivers that use backlights optionally will still fail to link if backlight support is disabled. Fix it by defining the stub when CONFIG_BACKLIGHT_CLASS_DEVICE is disabled. Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> --- include/linux/backlight.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/backlight.h b/include/linux/backlight.h index 5f2fd61ef4fb..fae0b189f7b4 100644 --- a/include/linux/backlight.h +++ b/include/linux/backlight.h @@ -162,7 +162,7 @@ struct generic_bl_info { void (*kick_battery)(void); }; -#ifdef CONFIG_OF +#if IS_ENABLED(CONFIG_OF) && IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE) struct backlight_device *of_find_backlight_by_node(struct device_node *node); #else static inline struct backlight_device * We might need to create stubs for backlight_force_update() and backlight_device_set_brightness() too. > Fixes: 39135a305a0f ("drm/omap: displays: panel-dpi: Support for handling > backlight devices") > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > --- > drivers/gpu/drm/omapdrm/displays/Kconfig | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/gpu/drm/omapdrm/displays/Kconfig > b/drivers/gpu/drm/omapdrm/displays/Kconfig index c226da145fb3..a349cb61961e > 100644 > --- a/drivers/gpu/drm/omapdrm/displays/Kconfig > +++ b/drivers/gpu/drm/omapdrm/displays/Kconfig > @@ -35,6 +35,7 @@ config DRM_OMAP_CONNECTOR_ANALOG_TV > > config DRM_OMAP_PANEL_DPI > tristate "Generic DPI panel" > + depends on BACKLIGHT_CLASS_DEVICE > help > Driver for generic DPI panels. -- Regards, Laurent Pinchart ^ permalink raw reply related [flat|nested] 8+ messages in thread
* Re: [PATCH 1/3] drm/omap: displays: panel-dpi: add backlight dependency 2017-04-19 20:21 ` [PATCH 1/3] drm/omap: displays: panel-dpi: add backlight dependency Laurent Pinchart @ 2017-04-19 20:39 ` Arnd Bergmann 2017-04-20 9:01 ` Jani Nikula 0 siblings, 1 reply; 8+ messages in thread From: Arnd Bergmann @ 2017-04-19 20:39 UTC (permalink / raw) To: Laurent Pinchart Cc: Tomi Valkeinen, David Airlie, dri-devel, Linux Kernel Mailing List On Wed, Apr 19, 2017 at 10:21 PM, Laurent Pinchart <laurent.pinchart@ideasonboard.com> wrote: >> >> This adds a dependency like we have for the other panel drivers. > > I believe the dependency should be made optional. DPI panels that don't need > backlight control should be supported by a kernel that has backlight support > compiled out. That would be nice in principle, but I fear this would cause additional problems. > --- a/include/linux/backlight.h > +++ b/include/linux/backlight.h > @@ -162,7 +162,7 @@ struct generic_bl_info { > void (*kick_battery)(void); > }; > > -#ifdef CONFIG_OF > +#if IS_ENABLED(CONFIG_OF) && IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE) > struct backlight_device *of_find_backlight_by_node(struct device_node *node); > #else > static inline struct backlight_device * > > > We might need to create stubs for backlight_force_update() and > backlight_device_set_brightness() too. > With BACKLIGHT_CLASS_DEVICE=m, you still get a link error when the user is in a built-in driver. Using 'depends on' usually solves this (except for drivers that cannot be modules). There are three possible workarounds for this that I can think of: - Use 'depends on BACKLIGHT_CLASS_DEVICE || BACKLIGHT_CLASS_DEVICE=n' in each driver that implements optional backlight support. We do this elsewhere, but it's confusing and easy to get wrong. - use IS_REACHABLE() instead of IS_ENABLED() when testing for backlight support. This will always result in a kernel that builds cleanly, but can be surprising for users when backlight support is a module that gets loaded at boot, but it is still not used. - Make BACKLIGHT_CLASS_DEVICE a 'bool' symbol instead, and force the core API code to always be built-in or completely disabled. This makes it really easy to use, at the expense of a larger kernel image for those that currently use a loadable module. Arnd ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH 1/3] drm/omap: displays: panel-dpi: add backlight dependency 2017-04-19 20:39 ` Arnd Bergmann @ 2017-04-20 9:01 ` Jani Nikula 0 siblings, 0 replies; 8+ messages in thread From: Jani Nikula @ 2017-04-20 9:01 UTC (permalink / raw) To: Arnd Bergmann, Laurent Pinchart Cc: Tomi Valkeinen, Linux Kernel Mailing List, dri-devel On Wed, 19 Apr 2017, Arnd Bergmann <arnd@arndb.de> wrote: > On Wed, Apr 19, 2017 at 10:21 PM, Laurent Pinchart > <laurent.pinchart@ideasonboard.com> wrote: >>> >>> This adds a dependency like we have for the other panel drivers. >> >> I believe the dependency should be made optional. DPI panels that don't need >> backlight control should be supported by a kernel that has backlight support >> compiled out. > > That would be nice in principle, but I fear this would cause additional > problems. > >> --- a/include/linux/backlight.h >> +++ b/include/linux/backlight.h >> @@ -162,7 +162,7 @@ struct generic_bl_info { >> void (*kick_battery)(void); >> }; >> >> -#ifdef CONFIG_OF >> +#if IS_ENABLED(CONFIG_OF) && IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE) >> struct backlight_device *of_find_backlight_by_node(struct device_node *node); >> #else >> static inline struct backlight_device * >> >> >> We might need to create stubs for backlight_force_update() and >> backlight_device_set_brightness() too. >> > > With BACKLIGHT_CLASS_DEVICE=m, you still get a link error when the user is > in a built-in driver. Using 'depends on' usually solves this (except for drivers > that cannot be modules). > > There are three possible workarounds for this that I can think of: > > - Use 'depends on BACKLIGHT_CLASS_DEVICE || BACKLIGHT_CLASS_DEVICE=n' > in each driver that implements optional backlight support. We do > this elsewhere, but > it's confusing and easy to get wrong. FWIW I think this is the fix, and not a workaround. "depends on FOO || FOO=n" is an expression used throughout the kernel, and it accurately describes the dependency here. Of course, all drivers implementing this must still wrap backlight class usage around IS_ENABLED(). BR, Jani. > > - use IS_REACHABLE() instead of IS_ENABLED() when testing for > backlight support. This will always result in a kernel that builds cleanly, > but can be surprising for users when backlight support is a module that > gets loaded at boot, but it is still not used. > > - Make BACKLIGHT_CLASS_DEVICE a 'bool' symbol instead, and force the > core API code to always be built-in or completely disabled. This makes > it really easy to use, at the expense of a larger kernel image for those that > currently use a loadable module. > > Arnd > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel -- Jani Nikula, Intel Open Source Technology Center ^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2017-06-14 18:13 UTC | newest] Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2017-04-19 17:59 [PATCH 1/3] drm/omap: displays: panel-dpi: add backlight dependency Arnd Bergmann 2017-04-19 17:59 ` [PATCH 2/3] drm/panel: S6E3HA2 needs backlight code Arnd Bergmann 2017-04-19 18:03 ` [PATCH 3/3] drm/panel: add backlight dependency for sitronix-st7789v Arnd Bergmann 2017-06-14 18:13 ` Thierry Reding 2017-06-14 18:13 ` [PATCH 2/3] drm/panel: S6E3HA2 needs backlight code Thierry Reding 2017-04-19 20:21 ` [PATCH 1/3] drm/omap: displays: panel-dpi: add backlight dependency Laurent Pinchart 2017-04-19 20:39 ` Arnd Bergmann 2017-04-20 9:01 ` Jani Nikula
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