On Wed, 12 Mar 2008 09:28:56 +0900 FUJITA Tomonori <fujita.tomonori@xxxxxxxxxxxxx> wrote: > On Wed, 12 Mar 2008 09:14:00 +0900 > FUJITA Tomonori <fujita.tomonori@xxxxxxxxxxxxx> wrote: > > > On Tue, 11 Mar 2008 16:09:26 -0400 (EDT) > > Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > > > > > On Tue, 11 Mar 2008, FUJITA Tomonori wrote: > > > > > > > On Mon, 10 Mar 2008 16:10:36 +0200 > > > > Boaz Harrosh <bharrosh@xxxxxxxxxxx> wrote: > > > > > > > > Have you had a look at drivers/usb/storage/protocol.c usb_stor_access_xfer_buf() ? > > > > > It looks like it could also use these, but there they have a twist where they want > > > > > to do it in parts. Do you think that the code there could also use the helpers > > > > > presented here somehow? (I know that one of the USB guys was asking about it) > > > > > > > > I've not. If the USB people are eager to use the new APIs, I'll try > > > > though I prefer to keep them simple. > > > > > > It would be great if the code could be removed from usb-storage and put > > > in a central library. The problem is, as Boaz mentioned, that some of > > > the subdrivers need to transfer their data in pieces. > > > > I'm fine with add a trick for USB to the APIs as long as USB people > > inspect and test the trick ;) > > > > > > > It may be that the device is able to send or receive only a few blocks > > > at a time, or it may be that the blocks aren't stored in continguous > > > locations on the device. Either way, the drivers need to do multiple > > > transfers, each starting from where the previous one left off. > > > > > > It shouldn't be too hard to adjust your code to make this work. > > > Instead of passing sgl and nents directly to sg_copy_buffer(), pass a > > > pointer to a structure containing fields for sgl, nents, n, sg_off, and > > > sg_copy. Then the caller could retain the ending values for use in a > > > later call. > > > > > > Does this sound reasonable? > > > > How about this? > > > > diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h > > index a3d567a..8951e3c 100644 > > --- a/include/linux/scatterlist.h > > +++ b/include/linux/scatterlist.h > > @@ -213,6 +213,13 @@ int __sg_alloc_table(struct sg_table *, unsigned int, unsigned int, gfp_t, > > sg_alloc_fn *); > > int sg_alloc_table(struct sg_table *, unsigned int, gfp_t); > > > > +int sg_copy_buffer(struct scatterlist **sgl, unsigned int nents, > > + unsigned long *offset, void *buf, int buflen, int to_buffer); > > +int sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents, > > + void *buf, int buflen); > > +int sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents, > > + void *buf, int buflen); > > + > > It enables us to simplify usb_stor_access_xfer_buf like this, I think > (it's not tested). I fixed some minor issues (comments, warning, etc) and I've uploaded the patchset: git://git.kernel.org/pub/scm/linux/kernel/git/tomo/linux-2.6-misc.git sg-copy -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
