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SubjectRe: [PATCH/RESEND] [media] VIDEO_CAFE_CCIC should select VIDEOBUF2_DMA_SG
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Hi Jon,

On Mon, Dec 15, 2014 at 3:04 PM, Jonathan Corbet <corbet@lwn.net> wrote:
> On Mon, 15 Dec 2014 14:55:37 +0100
> Geert Uytterhoeven <geert@linux-m68k.org> wrote:
>
>> If VIDEO_CAFE_CCIC=y, but VIDEOBUF2_DMA_SG=m:
>>
>> drivers/built-in.o: In function `mcam_v4l_open':
>> mcam-core.c:(.text+0x1c2e81): undefined reference to `vb2_dma_sg_memops'
>> mcam-core.c:(.text+0x1c2eb0): undefined reference to `vb2_dma_sg_init_ctx'
>> drivers/built-in.o: In function `mcam_v4l_release':
>> mcam-core.c:(.text+0x1c34bf): undefined reference to `vb2_dma_sg_cleanup_ctx'
>
> I've been mildly resistant to this because I've never figured out how
> such a configuration can come about. The Cafe chip only appeared in the
> OLPC XO-1 and cannot even come close to doing S/G I/O. So this patch
> robs a bit of memory for no use on a platform that can ill afford it.

If the driver cannot do SG, perhaps this block should be removed from
drivers/media/platform/marvell-ccic/mcam-core.h?

#if IS_ENABLED(CONFIG_VIDEOBUF2_DMA_SG)
#define MCAM_MODE_DMA_SG 1
#endif

Oh, this seems to be a reason for the breakage, too: IS_ENABLED()
evaluates to true for modular options...

> OTOH, the number of people building contemporary kernels for the XO-1 has
> got to be pretty small. So, in the interest of mollifying randconfig
> users out there, you can add my:
>
> Acked-by: Jonathan Corbet <corbet@lwn.net>

Thanks!

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds


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