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Date: Fri, 18 Oct 2013 18:06:02 -0700
From: Jon Mason <jon.mason@...el.com>
To: Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
Cc: dan.j.williams@...el.com, vinod.koul@...el.com,
dave.jiang@...el.com, t.figa@...sung.com,
kyungmin.park@...sung.com, linux@....linux.org.uk,
linux-kernel@...r.kernel.org, Dan Williams <djbw@...com>
Subject: Re: [PATCH v2 11/13] NTB: convert to dmaengine_unmap_data
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. Also, the
comment implies that NTB could not be compiled without DMA_ENGINE
support before, which it could be.
> stub functions to <linux/dmaengine.h> for dma_set_unmap(),
> dmaengine_get_unmap_data() and dmaengine_unmap_put().
>
> Cc: Dan Williams <djbw@...com>
> Cc: Vinod Koul <vinod.koul@...el.com>
> Cc: Tomasz Figa <t.figa@...sung.com>
> Cc: Dave Jiang <dave.jiang@...el.com>
> Cc: Jon Mason <jon.mason@...el.com>
> Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
> Signed-off-by: Kyungmin Park <kyungmin.park@...sung.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?
Thanks,
Jon
> if (!txd)
> - goto err3;
> + goto err2;
>
> txd->callback = ntb_rx_copy_callback;
> txd->callback_param = entry;
> + dma_set_unmap(txd, unmap);
>
> cookie = dmaengine_submit(txd);
> if (dma_submit_error(cookie))
> goto err3;
>
> + dmaengine_unmap_put(unmap);
> +
> qp->last_cookie = cookie;
>
> qp->rx_async++;
> @@ -1082,9 +1096,9 @@ static void ntb_async_rx(struct ntb_queue_entry *entry, void *offset,
> return;
>
> err3:
> - dma_unmap_single(device->dev, src, len, DMA_TO_DEVICE);
> + dmaengine_unmap_put(unmap);
> err2:
> - dma_unmap_single(device->dev, dest, len, DMA_FROM_DEVICE);
> + dmaengine_unmap_put(unmap);
> err1:
> /* If the callbacks come out of order, the writing of the index to the
> * last completed will be out of order. This may result in the
> @@ -1245,7 +1259,8 @@ static void ntb_async_tx(struct ntb_transport_qp *qp,
> struct dma_chan *chan = qp->dma_chan;
> struct dma_device *device;
> size_t dest_off, buff_off;
> - dma_addr_t src, dest;
> + struct dmaengine_unmap_data *unmap;
> + dma_addr_t dest;
> dma_cookie_t cookie;
> void __iomem *offset;
> size_t len = entry->len;
> @@ -1273,28 +1288,42 @@ static void ntb_async_tx(struct ntb_transport_qp *qp,
> if (!is_dma_copy_aligned(device, buff_off, dest_off, len))
> goto err;
>
> - src = dma_map_single(device->dev, buf, len, DMA_TO_DEVICE);
> - if (dma_mapping_error(device->dev, src))
> + unmap = dmaengine_get_unmap_data(device->dev, 1, GFP_NOIO);
> + if (!unmap)
> goto err;
>
> - flags = DMA_COMPL_SRC_UNMAP_SINGLE | DMA_PREP_INTERRUPT;
> - txd = device->device_prep_dma_memcpy(chan, dest, src, len, flags);
> + unmap->addr[0] = dma_map_page(device->dev, virt_to_page(buf),
> + buff_off, len, DMA_TO_DEVICE);
> + if (dma_mapping_error(device->dev, unmap->addr[0]))
> + goto err1;
> +
> + unmap->to_cnt = 1;
> +
> + flags = DMA_COMPL_SKIP_SRC_UNMAP | DMA_COMPL_SKIP_DEST_UNMAP |
> + DMA_PREP_INTERRUPT;
> + txd = device->device_prep_dma_memcpy(chan, dest, unmap->addr[0], len,
> + flags);
> if (!txd)
> goto err1;
>
> txd->callback = ntb_tx_copy_callback;
> txd->callback_param = entry;
> + dma_set_unmap(txd, unmap);
>
> cookie = dmaengine_submit(txd);
> if (dma_submit_error(cookie))
> - goto err1;
> + goto err2;
> +
> + dmaengine_unmap_put(unmap);
>
> dma_async_issue_pending(chan);
> qp->tx_async++;
>
> return;
> +err2:
> + dmaengine_unmap_put(unmap);
> err1:
> - dma_unmap_single(device->dev, src, len, DMA_TO_DEVICE);
> + dmaengine_unmap_put(unmap);
> err:
> ntb_memcpy_tx(entry, offset);
> qp->tx_memcpy++;
> diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
> index dc98bc5..3782cdb 100644
> --- a/include/linux/dmaengine.h
> +++ b/include/linux/dmaengine.h
> @@ -457,6 +457,7 @@ struct dma_async_tx_descriptor {
> #endif
> };
>
> +#ifdef CONFIG_DMA_ENGINE
> static inline void dma_set_unmap(struct dma_async_tx_descriptor *tx,
> struct dmaengine_unmap_data *unmap)
> {
> @@ -467,6 +468,20 @@ static inline void dma_set_unmap(struct dma_async_tx_descriptor *tx,
> struct dmaengine_unmap_data *
> dmaengine_get_unmap_data(struct device *dev, int nr, gfp_t flags);
> void dmaengine_unmap_put(struct dmaengine_unmap_data *unmap);
> +#else
> +static inline void dma_set_unmap(struct dma_async_tx_descriptor *tx,
> + struct dmaengine_unmap_data *unmap)
> +{
> +}
> +static inline struct dmaengine_unmap_data *
> +dmaengine_get_unmap_data(struct device *dev, int nr, gfp_t flags)
> +{
> + return NULL;
> +}
> +static inline void dmaengine_unmap_put(struct dmaengine_unmap_data *unmap)
> +{
> +}
> +#endif
>
> static inline void dma_descriptor_unmap(struct dma_async_tx_descriptor *tx)
> {
> --
> 1.8.2.3
>
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