[PATCH 1/2] drm/panel: remove unnecessary dependencies

[PATCH 1/2] drm/panel: remove unnecessary dependencies

[Russell King]

DRM_PANEL_LD9040 and DRM_PANEL_S6E8AA0 both explicitly depended on
DRM_PANEL && DRM.  This is nonsense for two reasons:

(a) DRM_PANEL already depends on DRM, so DRM_PANEL can not be enabled
without DRM first being enabled.  Hence the && DRM is useless.

(b) These two configs are already beneath a menu which depends on
DRM_PANEL being enabled; these options will not be visible without
DRM_PANEL already being enabled.

Let's just remove this unnecessary verbosity.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
---
 drivers/gpu/drm/panel/Kconfig | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
index 4ec874da5668..44aea730b3aa 100644
--- a/drivers/gpu/drm/panel/Kconfig
+++ b/drivers/gpu/drm/panel/Kconfig
@@ -18,14 +18,12 @@ config DRM_PANEL_SIMPLE
 
 config DRM_PANEL_LD9040
 	tristate "LD9040 RGB/SPI panel"
-	depends on DRM && DRM_PANEL
 	depends on OF
 	select SPI
 	select VIDEOMODE_HELPERS
 
 config DRM_PANEL_S6E8AA0
 	tristate "S6E8AA0 DSI video mode panel"
-	depends on DRM && DRM_PANEL
 	depends on OF
 	select DRM_MIPI_DSI
 	select VIDEOMODE_HELPERS
-- 
1.8.3.1

[PATCH 1/2] drm/panel: remove unnecessary dependencies

[Arnd Bergmann]

On Thursday 12 June 2014 16:50:15 Russell King wrote:
> DRM_PANEL_LD9040 and DRM_PANEL_S6E8AA0 both explicitly depended on
> DRM_PANEL && DRM.  This is nonsense for two reasons:
> 
> (a) DRM_PANEL already depends on DRM, so DRM_PANEL can not be enabled
> without DRM first being enabled.  Hence the && DRM is useless.
> 
> (b) These two configs are already beneath a menu which depends on
> DRM_PANEL being enabled; these options will not be visible without
> DRM_PANEL already being enabled.
> 
> Let's just remove this unnecessary verbosity.
> 
> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Unfortunately, this is wrong, because the current expression
exploits one of the finer details of Kconfig syntax:

>  drivers/gpu/drm/panel/Kconfig | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
> index 4ec874da5668..44aea730b3aa 100644
> --- a/drivers/gpu/drm/panel/Kconfig
> +++ b/drivers/gpu/drm/panel/Kconfig
> @@ -18,14 +18,12 @@ config DRM_PANEL_SIMPLE
>  
>  config DRM_PANEL_LD9040
>         tristate "LD9040 RGB/SPI panel"
> -       depends on DRM && DRM_PANEL
>         depends on OF
>         select SPI
>         select VIDEOMODE_HELPERS
>  
>  config DRM_PANEL_S6E8AA0
>         tristate "S6E8AA0 DSI video mode panel"
> -       depends on DRM && DRM_PANEL
>         depends on OF
>         select DRM_MIPI_DSI
>         select VIDEOMODE_HELPERS

DRM_PANEL is bool, while DRM is tristate. If DRM=m and DRM_PANEL=y,
these two options can only be 'n' or 'm' but not 'y' with the current
code, but they can be 'y' if you drop the explicit DRM dependency,
which will cause a link failure.

The DRM_PANEL dependency can be removed, it is indeed unnecessary.

	Arnd

[PATCH 1/2] drm/panel: remove unnecessary dependencies

[Russell King - ARM Linux]

On Thu, Jun 12, 2014 at 06:00:07PM +0200, Arnd Bergmann wrote:
> On Thursday 12 June 2014 16:50:15 Russell King wrote:
> > DRM_PANEL_LD9040 and DRM_PANEL_S6E8AA0 both explicitly depended on
> > DRM_PANEL && DRM.  This is nonsense for two reasons:
> > 
> > (a) DRM_PANEL already depends on DRM, so DRM_PANEL can not be enabled
> > without DRM first being enabled.  Hence the && DRM is useless.
> > 
> > (b) These two configs are already beneath a menu which depends on
> > DRM_PANEL being enabled; these options will not be visible without
> > DRM_PANEL already being enabled.
> > 
> > Let's just remove this unnecessary verbosity.
> > 
> > Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
> 
> Unfortunately, this is wrong, because the current expression
> exploits one of the finer details of Kconfig syntax:
> 
> >  drivers/gpu/drm/panel/Kconfig | 2 --
> >  1 file changed, 2 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
> > index 4ec874da5668..44aea730b3aa 100644
> > --- a/drivers/gpu/drm/panel/Kconfig
> > +++ b/drivers/gpu/drm/panel/Kconfig
> > @@ -18,14 +18,12 @@ config DRM_PANEL_SIMPLE
> >  
> >  config DRM_PANEL_LD9040
> >         tristate "LD9040 RGB/SPI panel"
> > -       depends on DRM && DRM_PANEL
> >         depends on OF
> >         select SPI
> >         select VIDEOMODE_HELPERS
> >  
> >  config DRM_PANEL_S6E8AA0
> >         tristate "S6E8AA0 DSI video mode panel"
> > -       depends on DRM && DRM_PANEL
> >         depends on OF
> >         select DRM_MIPI_DSI
> >         select VIDEOMODE_HELPERS
> 
> DRM_PANEL is bool, while DRM is tristate. If DRM=m and DRM_PANEL=y,
> these two options can only be 'n' or 'm' but not 'y' with the current
> code, but they can be 'y' if you drop the explicit DRM dependency,
> which will cause a link failure.
> 
> The DRM_PANEL dependency can be removed, it is indeed unnecessary.

In which case, that's a bug for DRM_PANEL_SIMPLE which uses the same
mechanism.  Since everything is going to be in the same boat, the
menu should depend on DRM && DRM_PANEL.

-- 
FTTC broadband for 0.8mile line: now at 9.7Mbps down 460kbps up... slowly
improving, and getting towards what was expected from it.

[PATCH 1/2] drm/panel: remove unnecessary dependencies

[Arnd Bergmann]

On Thursday 12 June 2014 17:04:34 Russell King - ARM Linux wrote:
> 
> In which case, that's a bug for DRM_PANEL_SIMPLE which uses the same
> mechanism.  Since everything is going to be in the same boat, the
> menu should depend on DRM && DRM_PANEL.
> 

Right, I actually have a patch for DRM_PANEL_SIMPLE in my randconfig
series that I haven't sent out. Making the menu depend on DRM
is probably correct, but I haven't tried.

	Arnd