Re: Two more patches required for soc_camera

[Guennadi Liakhovetski <g.liakhovetski@xxxxxxxxxxxxxx>]

On Fri, 8 Feb 2008, Mauro Carvalho Chehab wrote:

> > I think, "#include <linux/pci.h>" is needed for the current version of 
> > videobuf-dma-sg.c, which, however, doesn't necessarily mean, it works only 
> > on PCI-enabled platforms. Perhaps, the right fix would be to convert 
> > videobuf-dma-sg.c to purely dma API. In fact, it wouldn't be a very 
> > difficult task. Only these two prototypes in videobuf-dma-sg.h
> > 
> > int videobuf_pci_dma_map(struct pci_dev *pci,struct videobuf_dmabuf *dma);
> > int videobuf_pci_dma_unmap(struct pci_dev *pci,struct videobuf_dmabuf *dma);
> > 
> > and their implementations in videobuf-dma-sg.c should indeed be placed 
> > under #ifdef CONFIG_PCI. You would use enum dma_data_direction instead of 
> > PCI_DMA_FROMDEVICE and friends, call dma mapping and syncing functions 
> > directly, instead of their pci analogs, etc.
> 
> Yes. This seems to be the proper direction to me also.
> > 
> > Your proposal to use CONFIG_HAS_DMA might be a good interim solution. This 
> > is also in a way confirmed in a comment in 
> > include/asm-generic/dma-mapping-broken.h. The "dummy" pci-dma API 
> > conversions are defined in include/asm-generic/pci-dma-compat.h.
> 
> I think this won't work for some platforms. I remember someone adding PCI or
> other DMA dependency to some drivers, due to this (sorry, I can't remember the
> details of those patches).

Ok, how about

	depends on PCI || ARCH_PXA

? I think, this way we are safe.

> > Right, so, what would be your preference on this? It would be puty to hold 
> > off the patches ony because of this. If you want, I can try to look into 
> > converting videobuf-dma-sg.c to pci-free API, hopefully, for -rc2? And in 
> > the meantime maybe we could use the CONFIG_HAS_DMA?
> 
> Touching on videobuf-dma-sg is something very sensitive, since it affects most
> drivers. I would prefer to have this kind of commit happening during a
> merge window.
> 
> If we can't manage to have this happening for 2.6.25 window, let's postpone the
> PCI specific changesets to 2.6.26, merging they only at -mm series.

If we do accept the above solution, would we still want to move to dma 
API? And would you like me to try to do this or you'd prefer to do this 
yourself?

Thanks
Guennadi
---
Guennadi Liakhovetski

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