From: Paul Cercueil <paul@crapouillou.net>
To: "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
"Jonathan Corbet" <corbet@lwn.net>,
"Sumit Semwal" <sumit.semwal@linaro.org>,
"Christian König" <christian.koenig@amd.com>
Cc: "Jonathan Cameron" <jic23@kernel.org>,
"Nuno Sá" <noname.nuno@gmail.com>,
"Michael Hennerich" <Michael.Hennerich@analog.com>,
linux-usb@vger.kernel.org, linux-doc@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-media@vger.kernel.org,
dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org,
"Paul Cercueil" <paul@crapouillou.net>
Subject: [PATCH v5 1/6] dma-buf: Add dma_buf_{begin,end}_access()
Date: Fri, 19 Jan 2024 15:13:57 +0100 [thread overview]
Message-ID: <20240119141402.44262-2-paul@crapouillou.net> (raw)
In-Reply-To: <20240119141402.44262-1-paul@crapouillou.net>
These functions should be used by device drivers when they start and
stop accessing the data of DMABUF. It allows DMABUF importers to cache
the dma_buf_attachment while ensuring that the data they want to access
is available for their device when the DMA transfers take place.
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
---
v5: New patch
---
drivers/dma-buf/dma-buf.c | 66 +++++++++++++++++++++++++++++++++++++++
include/linux/dma-buf.h | 37 ++++++++++++++++++++++
2 files changed, 103 insertions(+)
diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index 8fe5aa67b167..a8bab6c18fcd 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -830,6 +830,8 @@ static struct sg_table * __map_dma_buf(struct dma_buf_attachment *attach,
* - dma_buf_mmap()
* - dma_buf_begin_cpu_access()
* - dma_buf_end_cpu_access()
+ * - dma_buf_begin_access()
+ * - dma_buf_end_access()
* - dma_buf_map_attachment_unlocked()
* - dma_buf_unmap_attachment_unlocked()
* - dma_buf_vmap_unlocked()
@@ -1602,6 +1604,70 @@ void dma_buf_vunmap_unlocked(struct dma_buf *dmabuf, struct iosys_map *map)
}
EXPORT_SYMBOL_NS_GPL(dma_buf_vunmap_unlocked, DMA_BUF);
+/**
+ * @dma_buf_begin_access - Call before any hardware access from/to the DMABUF
+ * @attach: [in] attachment used for hardware access
+ * @sg_table: [in] scatterlist used for the DMA transfer
+ * @direction: [in] direction of DMA transfer
+ */
+int dma_buf_begin_access(struct dma_buf_attachment *attach,
+ struct sg_table *sgt, enum dma_data_direction dir)
+{
+ struct dma_buf *dmabuf;
+ bool cookie;
+ int ret;
+
+ if (WARN_ON(!attach))
+ return -EINVAL;
+
+ dmabuf = attach->dmabuf;
+
+ if (!dmabuf->ops->begin_access)
+ return 0;
+
+ cookie = dma_fence_begin_signalling();
+ ret = dmabuf->ops->begin_access(attach, sgt, dir);
+ dma_fence_end_signalling(cookie);
+
+ if (WARN_ON_ONCE(ret))
+ return ret;
+
+ return 0;
+}
+EXPORT_SYMBOL_NS_GPL(dma_buf_begin_access, DMA_BUF);
+
+/**
+ * @dma_buf_end_access - Call after any hardware access from/to the DMABUF
+ * @attach: [in] attachment used for hardware access
+ * @sg_table: [in] scatterlist used for the DMA transfer
+ * @direction: [in] direction of DMA transfer
+ */
+int dma_buf_end_access(struct dma_buf_attachment *attach,
+ struct sg_table *sgt, enum dma_data_direction dir)
+{
+ struct dma_buf *dmabuf;
+ bool cookie;
+ int ret;
+
+ if (WARN_ON(!attach))
+ return -EINVAL;
+
+ dmabuf = attach->dmabuf;
+
+ if (!dmabuf->ops->end_access)
+ return 0;
+
+ cookie = dma_fence_begin_signalling();
+ ret = dmabuf->ops->end_access(attach, sgt, dir);
+ dma_fence_end_signalling(cookie);
+
+ if (WARN_ON_ONCE(ret))
+ return ret;
+
+ return 0;
+}
+EXPORT_SYMBOL_NS_GPL(dma_buf_end_access, DMA_BUF);
+
#ifdef CONFIG_DEBUG_FS
static int dma_buf_debug_show(struct seq_file *s, void *unused)
{
diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
index 8ff4add71f88..8ba612c7cc16 100644
--- a/include/linux/dma-buf.h
+++ b/include/linux/dma-buf.h
@@ -246,6 +246,38 @@ struct dma_buf_ops {
*/
int (*end_cpu_access)(struct dma_buf *, enum dma_data_direction);
+ /**
+ * @begin_access:
+ *
+ * This is called from dma_buf_begin_access() when a device driver
+ * wants to access the data of the DMABUF. The exporter can use this
+ * to flush/sync the caches if needed.
+ *
+ * This callback is optional.
+ *
+ * Returns:
+ *
+ * 0 on success or a negative error code on failure.
+ */
+ int (*begin_access)(struct dma_buf_attachment *, struct sg_table *,
+ enum dma_data_direction);
+
+ /**
+ * @end_access:
+ *
+ * This is called from dma_buf_end_access() when a device driver is
+ * done accessing the data of the DMABUF. The exporter can use this
+ * to flush/sync the caches if needed.
+ *
+ * This callback is optional.
+ *
+ * Returns:
+ *
+ * 0 on success or a negative error code on failure.
+ */
+ int (*end_access)(struct dma_buf_attachment *, struct sg_table *,
+ enum dma_data_direction);
+
/**
* @mmap:
*
@@ -606,6 +638,11 @@ void dma_buf_detach(struct dma_buf *dmabuf,
int dma_buf_pin(struct dma_buf_attachment *attach);
void dma_buf_unpin(struct dma_buf_attachment *attach);
+int dma_buf_begin_access(struct dma_buf_attachment *attach,
+ struct sg_table *sgt, enum dma_data_direction dir);
+int dma_buf_end_access(struct dma_buf_attachment *attach,
+ struct sg_table *sgt, enum dma_data_direction dir);
+
struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info);
int dma_buf_fd(struct dma_buf *dmabuf, int flags);
--
2.43.0
next prev parent reply other threads:[~2024-01-19 14:14 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-19 14:13 [PATCH v5 0/6] usb: gadget: functionfs: DMABUF import interface Paul Cercueil
2024-01-19 14:13 ` Paul Cercueil [this message]
2024-01-20 20:20 ` [PATCH v5 1/6] dma-buf: Add dma_buf_{begin,end}_access() kernel test robot
2024-01-22 10:35 ` [Linaro-mm-sig] " Christian König
2024-01-22 11:01 ` Paul Cercueil
2024-01-22 13:41 ` Christian König
2024-01-23 10:10 ` Paul Cercueil
2024-01-23 11:52 ` Christian König
2024-01-23 13:02 ` Paul Cercueil
[not found] ` <577501f9-9d1c-4f8d-9882-7c71090e5ef3@amd.com>
2024-01-24 10:58 ` Paul Cercueil
2024-01-24 15:38 ` Andrew Davis
2024-01-24 15:52 ` Paul Cercueil
[not found] ` <2ac7562c-d221-409a-bfee-1b3cfcc0f1c6@amd.com>
2024-01-25 18:01 ` Daniel Vetter
2024-01-26 16:42 ` Christian König
2024-01-30 9:01 ` [Linaro-mm-sig] " Daniel Vetter
[not found] ` <a2346244-e22b-4ff6-b6cd-1da7138725ae@amd.com>
2024-01-30 9:48 ` Paul Cercueil
2024-01-30 10:40 ` Daniel Vetter
2024-01-30 13:09 ` Christian König
2024-01-31 9:07 ` Daniel Vetter
2024-02-06 13:28 ` Christian König
2024-02-06 13:57 ` Daniel Vetter
2024-01-30 10:38 ` Daniel Vetter
2024-01-25 18:10 ` Daniel Vetter
2024-01-19 14:13 ` [PATCH v5 2/6] dma-buf: udmabuf: Implement .{begin,end}_access Paul Cercueil
2024-02-07 17:10 ` [Linaro-mm-sig] " Daniel Vetter
2024-01-19 14:13 ` [PATCH v5 3/6] usb: gadget: Support already-mapped DMA SGs Paul Cercueil
2024-01-19 14:14 ` [PATCH v5 4/6] usb: gadget: functionfs: Factorize wait-for-endpoint code Paul Cercueil
2024-01-19 14:14 ` [PATCH v5 5/6] usb: gadget: functionfs: Add DMABUF import interface Paul Cercueil
2024-01-19 14:14 ` [PATCH v5 6/6] Documentation: usb: Document FunctionFS DMABUF API Paul Cercueil
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