[PATCH v2] dmaengine: shdma: fix a build failure on platforms with no DMA support

[Guennadi Liakhovetski]

On Fri, 31 May 2013, Dan Murphy wrote:

> On 05/30/2013 10:01 PM, Guennadi Liakhovetski wrote:
> > On platforms with no support for the shdma dmaengine driver build is
> > currently failing with
> >
> > drivers/built-in.o: In function `sh_mobile_sdhi_probe':
> > drivers/mmc/host/sh_mobile_sdhi.c:170: undefined reference to`shdma_chan_filter'
> >
> > Fix the breakage by defining shdma_chan_filter to NULL in such
> > configurations.
> >
> > Signed-off-by: Guennadi Liakhovetski <g.liakhovetski+renesas at gmail.com>
> > ---
> >
> > v2: in "next" shdma_chan_filter() is defined in shdma-base.c, which is 
> > built if CONFIG_SH_DMAE_BASE is defined. This version uses the correct 
> > symbol.
> >
> > This is for "next." Compile-tested only. I'll test it on hardware next 
> > week, but I don't think it shall break anything.
> >
> >  include/linux/sh_dma.h |    4 ++++
> >  1 files changed, 4 insertions(+), 0 deletions(-)
> >
> > diff --git a/include/linux/sh_dma.h b/include/linux/sh_dma.h
> > index b64d6be..1fd8a20 100644
> > --- a/include/linux/sh_dma.h
> > +++ b/include/linux/sh_dma.h
> > @@ -99,6 +99,10 @@ struct sh_dmae_pdata {
> >  #define CHCR_TE	0x00000002
> >  #define CHCR_IE	0x00000004
> >  
> > +#if IS_ENABLED(CONFIG_SH_DMAE_BASE)
> >  bool shdma_chan_filter(struct dma_chan *chan, void *arg);
> > +#else
> > +#define shdma_chan_filter NULL
> OK I did not see a reply to my previous comment
> Would this not be better as a
> #else
> static inline bool shdma_chan_filter(struct dma_chan *chan, void *arg) { return false; }
> #endif
> 
> Otherwise runtime will call a NULL pointer

Have you looked at the code?:

		if (fn && !fn(chan, fn_param)) {

Have you considered, when this channel allocation at all has a chance to 
get as far as to checking the filter? Have you thought about the meaning 
of "inline" when uing a function to assign it to a pointer? Are you sure 
"will" is the right word here?

Thanks
Guennadi

> > +#endif
> >  
> >  #endif
> 
> 
> -- 
> ------------------
> Dan Murphy
> 

---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/