Hiroshi, Hari, > -----Original Message----- > From: Hiroshi DOYU [mailto:Hiroshi.DOYU@xxxxxxxxx] > Sent: Tuesday, May 04, 2010 12:59 AM > To: Aguirre, Sergio > Cc: Kanigeri, Hari; linux-omap@xxxxxxxxxxxxxxx > Subject: Re: [Query][omap iommu] Consulting iommu if a physical region is > "mappable" before actually mapping it > > From: "ext Aguirre, Sergio" <saaguirre@xxxxxx> > Subject: RE: [Query][omap iommu] Consulting iommu if a physical region is > "mappable" before actually mapping it > Date: Mon, 3 May 2010 21:23:46 +0200 > > > > > > >> -----Original Message----- > >> From: Kanigeri, Hari > >> Sent: Monday, May 03, 2010 2:09 PM > >> To: Aguirre, Sergio; Hiroshi DOYU > >> Cc: linux-omap@xxxxxxxxxxxxxxx > >> Subject: RE: [Query][omap iommu] Consulting iommu if a physical region > is > >> "mappable" before actually mapping it > >> > >> Sergio, > >> > >> > > >> > Can the iommu driver be "consulted" if a certain area (contiguous or > >> not) > >> > can be mapped or not, before even trying to do it? > >> > > >> > >> -- As long as there are physical pages backing the area it should be > >> mappable right ? > > > > Ok, well.. maybe my question was more about that, if the ISP MMU has > > some kind of limited translation table size, in which it has a > > limited of pages to map to device addresses that the ISP can use. > > > > The need for this is that, in camera, there's a Video4Linux2 IOCTL > > to know if a certain amount of buffers can be handled (and that > > includes if they could be mapped or not), even before actually doing > > the whole allocation/mapping. > > > > If there's no limitation in the translation table size, then I guess > > the only concern is to ensure we have enough free RAM to use. (Which > > I'll like to think that an userspace resource manager will be able > > to figure out for the camera application, which is the one > > allocating the buffers.) > > Right, currently a whole 4GB address space is available, so virtually > no limitation for the translation table size. OK, understood. Sorry if I asked dumb questions, but I'm not an expert on that area. Now I know. :) Thanks a lot for your patience and time! Regards, Sergio > -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
