Messages in this thread | | | Date | Tue, 22 Oct 2013 14:29:36 -0700 | Subject | Re: [PATCH v2 11/13] NTB: convert to dmaengine_unmap_data | From | Dan Williams <> |
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On Fri, Oct 18, 2013 at 6:06 PM, Jon Mason <jon.mason@intel.com> wrote: > On Fri, Oct 18, 2013 at 07:35:31PM +0200, Bartlomiej Zolnierkiewicz wrote: >> Use the generic unmap object to unmap dma buffers. >> >> As NTB can be compiled without DMA_ENGINE support add > > Seems like the stubs should be added outside of this patch.
I think they are ok here as this is the only driver that uses them. The alternative is a new api patch without a user.
> Also, the > comment implies that NTB could not be compiled without DMA_ENGINE > support before, which it could be.
Hmm, I read it as "since NTB *can* be compiled without dmaengine here are some stubs".
> >> stub functions to <linux/dmaengine.h> for dma_set_unmap(), >> dmaengine_get_unmap_data() and dmaengine_unmap_put(). >> >> Cc: Dan Williams <djbw@fb.com> >> Cc: Vinod Koul <vinod.koul@intel.com> >> Cc: Tomasz Figa <t.figa@samsung.com> >> Cc: Dave Jiang <dave.jiang@intel.com> >> Cc: Jon Mason <jon.mason@intel.com> >> Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> >> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com> >> --- >> drivers/ntb/ntb_transport.c | 63 +++++++++++++++++++++++++++++++++------------ >> include/linux/dmaengine.h | 15 +++++++++++ >> 2 files changed, 61 insertions(+), 17 deletions(-) >> >> diff --git a/drivers/ntb/ntb_transport.c b/drivers/ntb/ntb_transport.c >> index 12a9e83..fc6bbf1 100644 >> --- a/drivers/ntb/ntb_transport.c >> +++ b/drivers/ntb/ntb_transport.c >> @@ -1034,7 +1034,7 @@ static void ntb_async_rx(struct ntb_queue_entry *entry, void *offset, >> struct dma_chan *chan = qp->dma_chan; >> struct dma_device *device; >> size_t pay_off, buff_off; >> - dma_addr_t src, dest; >> + struct dmaengine_unmap_data *unmap; >> dma_cookie_t cookie; >> void *buf = entry->buf; >> unsigned long flags; >> @@ -1054,27 +1054,41 @@ static void ntb_async_rx(struct ntb_queue_entry *entry, void *offset, >> if (!is_dma_copy_aligned(device, pay_off, buff_off, len)) >> goto err1; >> >> - dest = dma_map_single(device->dev, buf, len, DMA_FROM_DEVICE); >> - if (dma_mapping_error(device->dev, dest)) >> + unmap = dmaengine_get_unmap_data(device->dev, 2, GFP_NOIO); >> + if (!unmap) >> goto err1; >> >> - src = dma_map_single(device->dev, offset, len, DMA_TO_DEVICE); >> - if (dma_mapping_error(device->dev, src)) >> + unmap->addr[0] = dma_map_page(device->dev, virt_to_page(offset), >> + pay_off, len, DMA_TO_DEVICE); >> + if (dma_mapping_error(device->dev, unmap->addr[0])) >> goto err2; >> >> - flags = DMA_COMPL_DEST_UNMAP_SINGLE | DMA_COMPL_SRC_UNMAP_SINGLE | >> + unmap->to_cnt = 1; >> + >> + unmap->addr[1] = dma_map_page(device->dev, virt_to_page(buf), >> + buff_off, len, DMA_FROM_DEVICE); >> + if (dma_mapping_error(device->dev, unmap->addr[1])) >> + goto err2; >> + >> + unmap->from_cnt = 1; >> + >> + flags = DMA_COMPL_SKIP_SRC_UNMAP | DMA_COMPL_SKIP_DEST_UNMAP | >> DMA_PREP_INTERRUPT; >> - txd = device->device_prep_dma_memcpy(chan, dest, src, len, flags); >> + txd = device->device_prep_dma_memcpy(chan, unmap->addr[1], >> + unmap->addr[0], len, flags); > > I must say, as a user I dislike this interface much less than the > previous. Can we abstract all of this away in a helper function > that simply takes the src, dest, and len, then maps and calls > device_prep_dma_memcpy? The driver does not keep track of the > dmaengine_unmap_data, so the helper function could simply return an > error if something isn't happy. Thoughts?
Well, that's almost dma_async_memcpy_pg_to_pg, except NTB wants it's own callback. We could add a new helper that does dma_async_memcpy_pg_to_pg() with callback, but I want to do a larger reorganization of dmaengine to try to kill off the need to specify the callback after ->prep(). Can we go with as is for now and cleanup later? The same is happening to the other clients in this patchset (async_tx, dmatest, net_dma) in terms of picking up unmap responsibility from the drivers. It looks "worse" for each client at this stage, but the overall effect is:
34 files changed, 538 insertions(+), 1157 deletions(-)
-- Dan
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