Stephen Warren <swarren@xxxxxxxxxxxxx> wrote @ Wed, 20 Jun 2012 19:11:51 +0200: > On 06/20/2012 01:16 AM, Hiroshi DOYU wrote: > > From: Hiroshi Doyu <hdoyu@xxxxxxxxxx> > > > > This code was based on: > > "arch/microblaze/kernel/prom_parse.c" > > "arch/powerpc/kernel/prom_parse.c" > > > > Can be promoted as a global function for general use to replace > > "of_parse_dma_window()" in the above. This supports different formats > > flexibly. "prefix" can be configured if any. "busno" and "index" are > > optionally specified. Set NULL and 0 if not used. > > > > Signed-off-by: Hiroshi DOYU <hdoyu@xxxxxxxxxx> > > --- > > Based on the discussion: > > http://marc.info/?l=linux-tegra&m=133732046606458&w=2 > > Hmmm. This function really should be in some common location and > available for all drivers to use. Can't we add it to that common > location from the start? What prevented the earlier patch that did this > from getting merged into 3.5? It's because there was no feedback against the original patches(the common location ones, *1,*2) from DT side. *1: http://article.gmane.org/gmane.linux.ports.tegra/4468 *2: https://lkml.org/lkml/2012/4/30/153 > One thing that might help here would be /not/ to add the common code to > drivers/of/of_dma.c as was done in the earlier revisions of this patch - > I believe that Grant has been trying to push subsystem-specific OF > functionality into files in those individual subsystems, so that > drivers/of can be kept for core support. Perhaps this patch should > create drivers/iommu/of_iommu.c or similar? "drivers/iommu/of_iommu.c" seems quite reasonable for this function. > But I wonder: Is this function likely to be useful outside of > drivers/iommu/ - you mentioned that similar code already exists in the > two arch-specific prom_parse.c files; where are the existing users of > those functions. If not in drivers/iommu/, then probably drivers/iommu/ > isn't a good place to put the new common function... There are the following 3 users of of_parse_dma_window() as below. All of them are IOMMU related, but they are architecture specific ones, not for the standard IOMMU API. I guess that the current trend is to convert Arch specific IOMMU API to the standard one basically. arch/powerpc/kernel/vio.c of_parse_dma_window(dev->dev.of_node, dma_window, arch/powerpc/platforms/cell/iommu.c of_parse_dma_window(np, dma_window, &index, base, size); arch/powerpc/platforms/pseries/iommu.c of_parse_dma_window(dn, dma_window, &tbl->it_index, &offset, &size); I think that the common "dma-window" DT parser is necessary for the standard IOMMU because "dma-window" info is dealt as DOMAIN_ATTR_GEOMETRY in the following Joerg's patch too. [PATCH 0/5] IOMMU: Make IOMMU-API ready for GART-like hardware https://lkml.org/lkml/2012/1/19/170 If it's ok to have of_get_dma_window() in "drivers/iommu/of_iommu.c", I'll post that version. Any comment? -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
