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Date: Wed, 26 May 2010 16:19:33 +0200
From: Richard Röjfors
<richard.rojfors@...agicore.com>
To: Mauro Carvalho Chehab <mchehab@...hat.com>
Cc: Linux Media Mailing List <linux-media@...r.kernel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Douglas Schilling Landgraf <dougsland@...il.com>,
Samuel Ortiz <sameo@...ux.intel.com>,
"Williams, Dan J" <dan.j.williams@...el.com>
Subject: Re: [PATCH 1/2] media: Add timberdale video-in driver
Hi Mauro,
On Sun, 2010-04-25 at 13:13 -0300, Mauro Carvalho Chehab wrote:
> >
> > 2.
> > I tried using videobuf-dma-contig, but got poor performance. I can not
> > really explain why, I though it's due to the fact that the contiguous
> > buffer is allocated coherent -> no caching.
> > I saw both gstreamer and mplayer perform very badly.
> > The frame grabber requires the DMA transfer for a frame beeing started
> > while the frame is decoded. When I tested using contigous buffers
> > gstreamer sometimes was that slow that it sometimes missed to have a
> > frame queued when a transfer was finished, so I got frame drops. Any
> > other ideas of the poor performance? otherwise I would like to go for
> > the double buffered solution.
>
> The better is to fix videobuf-dma_contig to better work on your hardware.
> It makes sense to add a flag to allow specifying if it should use coherent
> or non-coherent memory for the dma buffer alloc/free calls.
>
I have verified the performance issue and it goes back to non cached coherent buffers.
I did an update to the videobuf-dma-contig. I did it by adding another init function,
which calls videobuf_queue_core_init with another set of qops.
The other set uses the same functions as the uncached version, but a sync function
is added, and the alloc_functions are different.
What do you think?
Signed-off-by: Richard Röjfors <richard.rojfors@...agicore.com>
---
diff --git a/drivers/media/video/videobuf-dma-contig.c b/drivers/media/video/videobuf-dma-contig.c
index dce4f3a..2fc923c 100644
--- a/drivers/media/video/videobuf-dma-contig.c
+++ b/drivers/media/video/videobuf-dma-contig.c
@@ -27,6 +27,7 @@ struct videobuf_dma_contig_memory {
u32 magic;
void *vaddr;
dma_addr_t dma_handle;
+ bool cached;
unsigned long size;
int is_userptr;
};
@@ -38,6 +39,54 @@ struct videobuf_dma_contig_memory {
BUG(); \
}
+static int __videobuf_dc_alloc(struct device *dev,
+ struct videobuf_dma_contig_memory *mem, unsigned long size)
+{
+ mem->size = size;
+ if (mem->cached) {
+ mem->vaddr = kmalloc(mem->size, GFP_KERNEL);
+ if (mem->vaddr) {
+ int err;
+
+ mem->dma_handle = dma_map_single(dev, mem->vaddr,
+ mem->size, DMA_FROM_DEVICE);
+ err = dma_mapping_error(dev, mem->dma_handle);
+ if (err) {
+ dev_err(dev, "dma_map_single failed\n");
+
+ kfree(mem->vaddr);
+ mem->vaddr = 0;
+ return err;
+ }
+ }
+ } else
+ mem->vaddr = dma_alloc_coherent(dev, mem->size,
+ &mem->dma_handle, GFP_KERNEL);
+
+ if (!mem->vaddr) {
+ dev_err(dev, "memory alloc size %ld failed\n",
+ mem->size);
+ return -ENOMEM;
+ }
+
+ dev_dbg(dev, "dma mapped data is at %p (%ld)\n", mem->vaddr, mem->size);
+
+ return 0;
+}
+
+static void __videobuf_dc_free(struct device *dev,
+ struct videobuf_dma_contig_memory *mem)
+{
+ if (mem->cached) {
+ dma_unmap_single(dev, mem->dma_handle, mem->size,
+ DMA_FROM_DEVICE);
+ kfree(mem->vaddr);
+ } else
+ dma_free_coherent(dev, mem->size, mem->vaddr, mem->dma_handle);
+
+ mem->vaddr = NULL;
+}
+
static void
videobuf_vm_open(struct vm_area_struct *vma)
{
@@ -92,9 +141,7 @@ static void videobuf_vm_close(struct vm_area_struct *vma)
dev_dbg(map->q->dev, "buf[%d] freeing %p\n",
i, mem->vaddr);
- dma_free_coherent(q->dev, mem->size,
- mem->vaddr, mem->dma_handle);
- mem->vaddr = NULL;
+ __videobuf_dc_free(q->dev, mem);
}
q->bufs[i]->map = NULL;
@@ -190,7 +237,7 @@ static int videobuf_dma_contig_user_get(struct videobuf_dma_contig_memory *mem,
return ret;
}
-static void *__videobuf_alloc(size_t size)
+static void *__videobuf_alloc(size_t size, bool cached)
{
struct videobuf_dma_contig_memory *mem;
struct videobuf_buffer *vb;
@@ -199,11 +246,22 @@ static void *__videobuf_alloc(size_t size)
if (vb) {
mem = vb->priv = ((char *)vb) + size;
mem->magic = MAGIC_DC_MEM;
+ mem->cached = cached;
}
return vb;
}
+static void *__videobuf_alloc_uncached(size_t size)
+{
+ return __videobuf_alloc(size, false);
+}
+
+static void *__videobuf_alloc_cached(size_t size)
+{
+ return __videobuf_alloc(size, true);
+}
+
static void *__videobuf_to_vmalloc(struct videobuf_buffer *buf)
{
struct videobuf_dma_contig_memory *mem = buf->priv;
@@ -241,17 +299,8 @@ static int __videobuf_iolock(struct videobuf_queue *q,
return videobuf_dma_contig_user_get(mem, vb);
/* allocate memory for the read() method */
- mem->size = PAGE_ALIGN(vb->size);
- mem->vaddr = dma_alloc_coherent(q->dev, mem->size,
- &mem->dma_handle, GFP_KERNEL);
- if (!mem->vaddr) {
- dev_err(q->dev, "dma_alloc_coherent %ld failed\n",
- mem->size);
+ if (__videobuf_dc_alloc(q->dev, mem, PAGE_ALIGN(vb->size)))
return -ENOMEM;
- }
-
- dev_dbg(q->dev, "dma_alloc_coherent data is at %p (%ld)\n",
- mem->vaddr, mem->size);
break;
case V4L2_MEMORY_OVERLAY:
default:
@@ -276,6 +325,20 @@ static int __videobuf_mmap_free(struct videobuf_queue *q)
return 0;
}
+static int __videobuf_sync(struct videobuf_queue *q,
+ struct videobuf_buffer *buf)
+{
+ struct videobuf_dma_contig_memory *mem = buf->priv;
+ BUG_ON(!mem);
+ MAGIC_CHECK(mem->magic, MAGIC_DC_MEM);
+
+ dma_sync_single_for_cpu(q->dev, mem->dma_handle, mem->size,
+ DMA_FROM_DEVICE);
+
+ return 0;
+}
+
+
static int __videobuf_mmap_mapper(struct videobuf_queue *q,
struct vm_area_struct *vma)
{
@@ -321,30 +384,22 @@ static int __videobuf_mmap_mapper(struct videobuf_queue *q,
BUG_ON(!mem);
MAGIC_CHECK(mem->magic, MAGIC_DC_MEM);
- mem->size = PAGE_ALIGN(q->bufs[first]->bsize);
- mem->vaddr = dma_alloc_coherent(q->dev, mem->size,
- &mem->dma_handle, GFP_KERNEL);
- if (!mem->vaddr) {
- dev_err(q->dev, "dma_alloc_coherent size %ld failed\n",
- mem->size);
+ if (__videobuf_dc_alloc(q->dev, mem, PAGE_ALIGN(q->bufs[first]->bsize)))
goto error;
- }
- dev_dbg(q->dev, "dma_alloc_coherent data is at addr %p (size %ld)\n",
- mem->vaddr, mem->size);
/* Try to remap memory */
size = vma->vm_end - vma->vm_start;
size = (size < mem->size) ? size : mem->size;
- vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+ if (!mem->cached)
+ vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
retval = remap_pfn_range(vma, vma->vm_start,
mem->dma_handle >> PAGE_SHIFT,
size, vma->vm_page_prot);
if (retval) {
dev_err(q->dev, "mmap: remap failed with error %d. ", retval);
- dma_free_coherent(q->dev, mem->size,
- mem->vaddr, mem->dma_handle);
+ __videobuf_dc_free(q->dev, mem);
goto error;
}
@@ -422,9 +477,22 @@ static int __videobuf_copy_stream(struct videobuf_queue *q,
static struct videobuf_qtype_ops qops = {
.magic = MAGIC_QTYPE_OPS,
- .alloc = __videobuf_alloc,
+ .alloc = __videobuf_alloc_uncached,
+ .iolock = __videobuf_iolock,
+ .mmap_free = __videobuf_mmap_free,
+ .mmap_mapper = __videobuf_mmap_mapper,
+ .video_copy_to_user = __videobuf_copy_to_user,
+ .copy_stream = __videobuf_copy_stream,
+ .vmalloc = __videobuf_to_vmalloc,
+};
+
+static struct videobuf_qtype_ops qops_cached = {
+ .magic = MAGIC_QTYPE_OPS,
+
+ .alloc = __videobuf_alloc_cached,
.iolock = __videobuf_iolock,
.mmap_free = __videobuf_mmap_free,
+ .sync = __videobuf_sync,
.mmap_mapper = __videobuf_mmap_mapper,
.video_copy_to_user = __videobuf_copy_to_user,
.copy_stream = __videobuf_copy_stream,
@@ -445,6 +513,20 @@ void videobuf_queue_dma_contig_init(struct videobuf_queue *q,
}
EXPORT_SYMBOL_GPL(videobuf_queue_dma_contig_init);
+void videobuf_queue_dma_contig_init_cached(struct videobuf_queue *q,
+ const struct videobuf_queue_ops *ops,
+ struct device *dev,
+ spinlock_t *irqlock,
+ enum v4l2_buf_type type,
+ enum v4l2_field field,
+ unsigned int msize,
+ void *priv)
+{
+ videobuf_queue_core_init(q, ops, dev, irqlock, type, field, msize,
+ priv, &qops_cached);
+}
+EXPORT_SYMBOL_GPL(videobuf_queue_dma_contig_init_cached);
+
dma_addr_t videobuf_to_dma_contig(struct videobuf_buffer *buf)
{
struct videobuf_dma_contig_memory *mem = buf->priv;
@@ -481,9 +563,7 @@ void videobuf_dma_contig_free(struct videobuf_queue *q,
return;
}
- /* read() method */
- dma_free_coherent(q->dev, mem->size, mem->vaddr, mem->dma_handle);
- mem->vaddr = NULL;
+ __videobuf_dc_free(q->dev, mem);
}
EXPORT_SYMBOL_GPL(videobuf_dma_contig_free);
diff --git a/include/media/videobuf-dma-contig.h b/include/media/videobuf-dma-contig.h
index ebaa9bc..43b94cd 100644
--- a/include/media/videobuf-dma-contig.h
+++ b/include/media/videobuf-dma-contig.h
@@ -25,6 +25,15 @@ void videobuf_queue_dma_contig_init(struct videobuf_queue *q,
unsigned int msize,
void *priv);
+void videobuf_queue_dma_contig_init_cached(struct videobuf_queue *q,
+ const struct videobuf_queue_ops *ops,
+ struct device *dev,
+ spinlock_t *irqlock,
+ enum v4l2_buf_type type,
+ enum v4l2_field field,
+ unsigned int msize,
+ void *priv);
+
dma_addr_t videobuf_to_dma_contig(struct videobuf_buffer *buf);
void videobuf_dma_contig_free(struct videobuf_queue *q,
struct videobuf_buffer *buf);
--
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