Re: [PATCH] [media] staging: allow omap4iss to be modular

[Arnd Bergmann <arnd@arndb.de>]

On Wednesday 11 June 2014 09:42:04 Nishanth Menon wrote:
> On 06/11/2014 09:35 AM, Arnd Bergmann wrote:
> > The OMAP4 camera support depends on I2C and VIDEO_V4L2, both
> > of which can be loadable modules. This causes build failures
> > if we want the camera driver to be built-in.
> > 
> > This can be solved by turning the option into "tristate",
> > which unfortunately causes another problem, because the
> > driver incorrectly calls a platform-internal interface
> > for omap4_ctrl_pad_readl/omap4_ctrl_pad_writel.
> > To work around that, we can export those symbols, but
> > that isn't really the correct solution, as we should not
> > have dependencies on platform code this way.
> > 
> > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> > ---
> > This is one of just two patches we currently need to get
> > 'make allmodconfig' to build again on ARM.
> > 
> > diff --git a/arch/arm/mach-omap2/control.c b/arch/arm/mach-omap2/control.c
> > index 751f354..05d2d98 100644
> > --- a/arch/arm/mach-omap2/control.c
> > +++ b/arch/arm/mach-omap2/control.c
> > @@ -190,11 +190,13 @@ u32 omap4_ctrl_pad_readl(u16 offset)
> >  {
> >  	return readl_relaxed(OMAP4_CTRL_PAD_REGADDR(offset));
> >  }
> > +EXPORT_SYMBOL_GPL(omap4_ctrl_pad_readl);
> >  
> >  void omap4_ctrl_pad_writel(u32 val, u16 offset)
> >  {
> >  	writel_relaxed(val, OMAP4_CTRL_PAD_REGADDR(offset));
> >  }
> > +EXPORT_SYMBOL_GPL(omap4_ctrl_pad_writel);
> >  
> >  #ifdef CONFIG_ARCH_OMAP3
> >  
> > diff --git a/drivers/staging/media/omap4iss/Kconfig b/drivers/staging/media/omap4iss/Kconfig
> > index 78b0fba..0c3e3c1 100644
> > --- a/drivers/staging/media/omap4iss/Kconfig
> > +++ b/drivers/staging/media/omap4iss/Kconfig
> > @@ -1,5 +1,5 @@
> >  config VIDEO_OMAP4
> > -	bool "OMAP 4 Camera support"
> > +	tristate "OMAP 4 Camera support"
> >  	depends on VIDEO_V4L2 && VIDEO_V4L2_SUBDEV_API && I2C && ARCH_OMAP4
> >  	select VIDEOBUF2_DMA_CONTIG
> >  	---help---
> > 
> 
> This was discussed in detail here:
> http://marc.info/?t=140198692500001&r=1&w=2
> Direct dependency from a staging driver to mach-omap2 driver is not
> something we'd like, right?

So it was decided to just leave ARM allmodconfig broken?

Why not at least do this instead?

8<----
>From 3a965f4fd5a6b3ef4a66aa4e7c916cfd34fd5706 Mon Sep 17 00:00:00 2001
From: Arnd Bergmann <arnd@arndb.de>
Date: Tue, 21 Jan 2014 09:32:43 +0100
Subject: [PATCH] [media] staging: tighten omap4iss dependencies

The OMAP4 camera support depends on I2C and VIDEO_V4L2, both
of which can be loadable modules. This causes build failures
if we want the camera driver to be built-in.

This can be solved by turning the option into "tristate",
which unfortunately causes another problem, because the
driver incorrectly calls a platform-internal interface
for omap4_ctrl_pad_readl/omap4_ctrl_pad_writel.

Instead, this patch just forbids the invalid configurations
and ensures that the driver can only be built if all its
dependencies are built-in.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

diff --git a/drivers/staging/media/omap4iss/Kconfig b/drivers/staging/media/omap4iss/Kconfig
index 78b0fba..8afc6fe 100644
--- a/drivers/staging/media/omap4iss/Kconfig
+++ b/drivers/staging/media/omap4iss/Kconfig
@@ -1,6 +1,6 @@
 config VIDEO_OMAP4
 	bool "OMAP 4 Camera support"
-	depends on VIDEO_V4L2 && VIDEO_V4L2_SUBDEV_API && I2C && ARCH_OMAP4
+	depends on VIDEO_V4L2=y && VIDEO_V4L2_SUBDEV_API && I2C=y && ARCH_OMAP4
 	select VIDEOBUF2_DMA_CONTIG
 	---help---
 	  Driver for an OMAP 4 ISS controller.