Re: [PATCH] staging: fbtft: Disable DMA support if DMA is not available

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Thu, Apr 23, 2015 at 08:06:52PM +0200, Geert Uytterhoeven wrote:
> If NO_DMA=y:
> 
>     drivers/built-in.o: In function `fbtft_framebuffer_alloc':
>     (.text+0xb53cae): undefined reference to `dmam_alloc_coherent'
> 
> As DMA support is already optional, make it depend on HAS_DMA.
> 
> Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
> ---
>  drivers/staging/fbtft/fbtft-core.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/staging/fbtft/fbtft-core.c b/drivers/staging/fbtft/fbtft-core.c
> index 53b748be27124793..88bf4705ebadc590 100644
> --- a/drivers/staging/fbtft/fbtft-core.c
> +++ b/drivers/staging/fbtft/fbtft-core.c
> @@ -47,9 +47,13 @@ static unsigned long debug;
>  module_param(debug, ulong, 0);
>  MODULE_PARM_DESC(debug, "override device debug level");
>  
> +#ifdef CONFIG_HAS_DMA
>  static bool dma = true;
>  module_param(dma, bool, 0);
>  MODULE_PARM_DESC(dma, "Use DMA buffer");
> +#else
> +static const bool dma;
> +#endif
>  

I don't see how this change can fix the build error you show above.
What am I missing?

thanks,

greg k-h