On Feb 15, 2008 2:53 AM, Haavard Skinnemoen <[EMAIL PROTECTED]> wrote: > On Wed, 13 Feb 2008 20:24:02 +0100 > Haavard Skinnemoen <[EMAIL PROTECTED]> wrote: > > > But looking at your latest patch series, I guess we can use the new > > "next" field instead. It's not like we really need the full > > capabilities of list_head. > > On second thought, if we do this, we would be using the "next" field in > an undocumented way. It is currently documented as follows: > > * @next: at completion submit this descriptor > > But that's not how we're going to use it when doing slave transfers: > We're using it to keep track of all the descriptors that have already > been submitted. > > I think it would actually be better to go the other way and have the > async_tx API extend the descriptor as well for its private fields. That > way, we get the pointer we need, but we can document it differently. > > So how about we do something along the lines of the patch below? We > need to update all the users too of course, but apart from making the > dma_slave_descriptor struct smaller, I don't think it will change the > actual memory layout at all. >
I like the direction of the patch, i.e. splitting out separate functionality into separate structs. However, I do not want to break the model of clients sourcing the operations and drivers sinking them which dma_slave_descriptor appears to do. How about adding a scatterlist pointer and an 'unmap_type' to the common descriptor? Where unmap_type selects between, page, single, sg, or no-unmap. Drivers already know the length and direction. Regards, Dan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
