Re: [Bugme-new] [Bug 40492] New: FB_BACKLIGHT should be set by

Re: [Bugme-new] [Bug 40492] New: FB_BACKLIGHT should be set by

[Randy Dunlap]

On Wed, 3 Aug 2011 18:55:41 GMT bugzilla-daemon@bugzilla.kernel.org wrote:

> https://bugzilla.kernel.org/show_bug.cgi?id@492
> 
>            Summary: FB_BACKLIGHT should be set by BACKLIGHT_CLASS_DEVICE
>            Product: Other
>            Version: 2.5
>     Kernel Version: 3.0.0
>           Platform: All
>         OS/Version: Linux
>               Tree: Mainline
>             Status: NEW
>           Severity: normal
>           Priority: P1
>          Component: Configuration
>         AssignedTo: other_configuration@kernel-bugs.osdl.org
>         ReportedBy: StormByte@gmail.com
>         Regression: No
> 
> 
> Created an attachment (idg432)
>  --> (https://bugzilla.kernel.org/attachment.cgi?idg432)
> Kernel's config
> 
> I discovered a scenario in which menuconfig fails to set FB_BACKLIGHT symbol
> when needed.
> 
> In my case, I have propietary nvidia drivers once loaded Xorg, but in the
> meanwhile, I have configured an uvesafb framebuffer (thus, no other framebuffer
> active nor compiled).
> 
> System works ok, but when trying to install nvidiabl[1] (to control nvidia's
> backlight) I find that FB_BACKLIGHT is not set where it should be because I
> have BACKLIGHT_CLASS_DEVICE set.
> 
> The result is that nvidiabl does not compile.
> 
> The workarround for this now is to enable as a modile any component with
> support for backlight [Nvidia Framebuffer (CONFIG_FB_NVIDIA), ATI Radeon
> display (CONFIG_FB_RADEON), etc...]
> 
> I propose either enabling it automatically with CONFIG_BACKLIGHT_CLASS_DEVICE,
> or either having a separate option to allow it to be selected manually for
> external modules.
> 
> I add an attachment of a kernel config showing this scenario with FB_BACKLIGHT
> not set nor any other framebuffer than uvesafb
> 
> -- 

Any fbdev comments on this bug report?

---
~Randy
*** Remember to use Documentation/SubmitChecklist when testing your code ***

Re: [Bugme-new] [Bug 40492] New: FB_BACKLIGHT should be set by

[Michel Dänzer]

On Mit, 2011-08-03 at 17:55 -0700, Randy Dunlap wrote: 
> On Wed, 3 Aug 2011 18:55:41 GMT bugzilla-daemon@bugzilla.kernel.org wrote:
> 
> > https://bugzilla.kernel.org/show_bug.cgi?id@492
> > 
> >            Summary: FB_BACKLIGHT should be set by BACKLIGHT_CLASS_DEVICE
> >            Product: Other
> >            Version: 2.5
> >     Kernel Version: 3.0.0
> >           Platform: All
> >         OS/Version: Linux
> >               Tree: Mainline
> >             Status: NEW
> >           Severity: normal
> >           Priority: P1
> >          Component: Configuration
> >         AssignedTo: other_configuration@kernel-bugs.osdl.org
> >         ReportedBy: StormByte@gmail.com
> >         Regression: No
> > 
> > 
> > Created an attachment (idg432)
> >  --> (https://bugzilla.kernel.org/attachment.cgi?idg432)
> > Kernel's config
> > 
> > I discovered a scenario in which menuconfig fails to set FB_BACKLIGHT symbol
> > when needed.
> > 
> > In my case, I have propietary nvidia drivers once loaded Xorg, but in the
> > meanwhile, I have configured an uvesafb framebuffer (thus, no other framebuffer
> > active nor compiled).
> > 
> > System works ok, but when trying to install nvidiabl[1] (to control nvidia's
> > backlight) I find that FB_BACKLIGHT is not set where it should be because I
> > have BACKLIGHT_CLASS_DEVICE set.
> > 
> > The result is that nvidiabl does not compile.

Sounds like an nvidiabl bug. I'm successfully using backlight control
with radeon KMS with

# CONFIG_FB_BACKLIGHT is not set
CONFIG_BACKLIGHT_CLASS_DEVICE=m


-- 
Earthling Michel Dänzer           |                   http://www.amd.com
Libre software enthusiast         |          Debian, X and DRI developer

Re: [Bugme-new] [Bug 40492] New: FB_BACKLIGHT should be set by BACKLIGHT_CLASS_DEVICE

[David]

On Thursday 04 August 2011 07:55:16 you wrote:
> On Mit, 2011-08-03 at 17:55 -0700, Randy Dunlap wrote:
> > On Wed, 3 Aug 2011 18:55:41 GMT bugzilla-daemon@bugzilla.kernel.org wrote:
> > > https://bugzilla.kernel.org/show_bug.cgi?id@492
> > > 
> > >            Summary: FB_BACKLIGHT should be set by
> > >            BACKLIGHT_CLASS_DEVICE Product: Other
> > >            Version: 2.5
> > >     
> > >     Kernel Version: 3.0.0
> > >     
> > >           Platform: All
> > >         
> > >         OS/Version: Linux
> > >         
> > >               Tree: Mainline
> > >             
> > >             Status: NEW
> > >           
> > >           Severity: normal
> > >           Priority: P1
> > >          
> > >          Component: Configuration
> > >         
> > >         AssignedTo: other_configuration@kernel-bugs.osdl.org
> > >         ReportedBy: StormByte@gmail.com
> > >         Regression: No
> > > 
> > > Created an attachment (idg432)
> > > 
> > >  --> (https://bugzilla.kernel.org/attachment.cgi?idg432)
> > > 
> > > Kernel's config
> > > 
> > > I discovered a scenario in which menuconfig fails to set
> > > FB_BACKLIGHT symbol when needed.
> > > 
> > > In my case, I have propietary nvidia drivers once loaded Xorg, but
> > > in the meanwhile, I have configured an uvesafb framebuffer (thus,
> > > no other framebuffer active nor compiled).
> > > 
> > > System works ok, but when trying to install nvidiabl[1] (to control
> > > nvidia's backlight) I find that FB_BACKLIGHT is not set where it
> > > should be because I have BACKLIGHT_CLASS_DEVICE set.
> > > 
> > > The result is that nvidiabl does not compile.
> 
> Sounds like an nvidiabl bug. I'm successfully using backlight control
> with radeon KMS with
> 
> # CONFIG_FB_BACKLIGHT is not set
> CONFIG_BACKLIGHT_CLASS_DEVICE=m

It does not seem a bug in nvidiabl, it needs this symbol in order to get 2 
defines (from include/linux/fb.h)
394 #ifdef CONFIG_FB_BACKLIGHT
395 /* Settings for the generic backlight code */
396 #define FB_BACKLIGHT_LEVELS     128
397 #define FB_BACKLIGHT_MAX        0xFF
398 #endif

I think nvidiabl uses those instead of having them hardcoded in its source, 
and thus not a bug really.

Re: [Bugme-new] [Bug 40492] New: FB_BACKLIGHT should be set by

[Michel Dänzer]

On Don, 2011-08-04 at 14:04 +0200, David wrote: 
> On Thursday 04 August 2011 07:55:16 you wrote:
> > On Mit, 2011-08-03 at 17:55 -0700, Randy Dunlap wrote:
> > > On Wed, 3 Aug 2011 18:55:41 GMT bugzilla-daemon@bugzilla.kernel.org wrote:
> > > > https://bugzilla.kernel.org/show_bug.cgi?id@492
> > > > 
> > > >            Summary: FB_BACKLIGHT should be set by
> > > >            BACKLIGHT_CLASS_DEVICE Product: Other
> > > >            Version: 2.5
> > > >     
> > > >     Kernel Version: 3.0.0
> > > >     
> > > >           Platform: All
> > > >         
> > > >         OS/Version: Linux
> > > >         
> > > >               Tree: Mainline
> > > >             
> > > >             Status: NEW
> > > >           
> > > >           Severity: normal
> > > >           Priority: P1
> > > >          
> > > >          Component: Configuration
> > > >         
> > > >         AssignedTo: other_configuration@kernel-bugs.osdl.org
> > > >         ReportedBy: StormByte@gmail.com
> > > >         Regression: No
> > > > 
> > > > Created an attachment (idg432)
> > > > 
> > > >  --> (https://bugzilla.kernel.org/attachment.cgi?idg432)
> > > > 
> > > > Kernel's config
> > > > 
> > > > I discovered a scenario in which menuconfig fails to set
> > > > FB_BACKLIGHT symbol when needed.
> > > > 
> > > > In my case, I have propietary nvidia drivers once loaded Xorg, but
> > > > in the meanwhile, I have configured an uvesafb framebuffer (thus,
> > > > no other framebuffer active nor compiled).
> > > > 
> > > > System works ok, but when trying to install nvidiabl[1] (to control
> > > > nvidia's backlight) I find that FB_BACKLIGHT is not set where it
> > > > should be because I have BACKLIGHT_CLASS_DEVICE set.
> > > > 
> > > > The result is that nvidiabl does not compile.
> > 
> > Sounds like an nvidiabl bug. I'm successfully using backlight control
> > with radeon KMS with
> > 
> > # CONFIG_FB_BACKLIGHT is not set
> > CONFIG_BACKLIGHT_CLASS_DEVICE=m
> 
> It does not seem a bug in nvidiabl, it needs this symbol in order to get 2 
> defines (from include/linux/fb.h)
> 394 #ifdef CONFIG_FB_BACKLIGHT
> 395 /* Settings for the generic backlight code */
> 396 #define FB_BACKLIGHT_LEVELS     128
> 397 #define FB_BACKLIGHT_MAX        0xFF
> 398 #endif
> 
> I think nvidiabl uses those instead of having them hardcoded in its source, 
> and thus not a bug really.

If those defines are relevant outside of CONFIG_FB_BACKLIGHT (radeon KMS
doesn't use them), they should probably be defined somewhere else.


-- 
Earthling Michel Dänzer           |                   http://www.amd.com
Libre software enthusiast         |          Debian, X and DRI developer

Re: [Bugme-new] [Bug 40492] New: FB_BACKLIGHT should be set by

[Randy Dunlap]

On Thu, 04 Aug 2011 14:04:46 +0200 David wrote:

> On Thursday 04 August 2011 07:55:16 you wrote:
> > On Mit, 2011-08-03 at 17:55 -0700, Randy Dunlap wrote:
> > > On Wed, 3 Aug 2011 18:55:41 GMT bugzilla-daemon@bugzilla.kernel.org wrote:
> > > > https://bugzilla.kernel.org/show_bug.cgi?id@492
> > > > 
> > > >            Summary: FB_BACKLIGHT should be set by
> > > >            BACKLIGHT_CLASS_DEVICE Product: Other
> > > >            Version: 2.5
> > > >     
> > > >     Kernel Version: 3.0.0
> > > >     
> > > >           Platform: All
> > > >         
> > > >         OS/Version: Linux
> > > >         
> > > >               Tree: Mainline
> > > >             
> > > >             Status: NEW
> > > >           
> > > >           Severity: normal
> > > >           Priority: P1
> > > >          
> > > >          Component: Configuration
> > > >         
> > > >         AssignedTo: other_configuration@kernel-bugs.osdl.org
> > > >         ReportedBy: StormByte@gmail.com
> > > >         Regression: No
> > > > 
> > > > Created an attachment (idg432)
> > > > 
> > > >  --> (https://bugzilla.kernel.org/attachment.cgi?idg432)
> > > > 
> > > > Kernel's config
> > > > 
> > > > I discovered a scenario in which menuconfig fails to set
> > > > FB_BACKLIGHT symbol when needed.
> > > > 
> > > > In my case, I have propietary nvidia drivers once loaded Xorg, but
> > > > in the meanwhile, I have configured an uvesafb framebuffer (thus,
> > > > no other framebuffer active nor compiled).
> > > > 
> > > > System works ok, but when trying to install nvidiabl[1] (to control
> > > > nvidia's backlight) I find that FB_BACKLIGHT is not set where it
> > > > should be because I have BACKLIGHT_CLASS_DEVICE set.
> > > > 
> > > > The result is that nvidiabl does not compile.
> > 
> > Sounds like an nvidiabl bug. I'm successfully using backlight control
> > with radeon KMS with
> > 
> > # CONFIG_FB_BACKLIGHT is not set
> > CONFIG_BACKLIGHT_CLASS_DEVICE=m
> 
> It does not seem a bug in nvidiabl, it needs this symbol in order to get 2 
> defines (from include/linux/fb.h)
> 394 #ifdef CONFIG_FB_BACKLIGHT
> 395 /* Settings for the generic backlight code */
> 396 #define FB_BACKLIGHT_LEVELS     128
> 397 #define FB_BACKLIGHT_MAX        0xFF
> 398 #endif
> 
> I think nvidiabl uses those instead of having them hardcoded in its source, 
> and thus not a bug really.

David,

You could propose a patch that makes those 2 defines not be conditional
on the CONFIB_FB_BACKLIGHT symbol.

Or you could propose a patch that makes the FB_BACKLIGHT symbol
user-configurable.  Currently it is not user-configurable since it
does not have a prompt string.  I think all it would take is
changing the "bool" line to include a prompt string and adding some
help text.  Something like (not tested, probably needs some
wordsmithing):

config FB_BACKLIGHT
	bool "Generic video backlight support"
	depends on FB
	select BACKLIGHT_LCD_SUPPORT
	select BACKLIGHT_CLASS_DEVICE
	default n
	help
	  This option provides a little video backlight support.
	  Most drivers that need it enable it automatically.

---
~Randy
*** Remember to use Documentation/SubmitChecklist when testing your code ***