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V4L/DVB (6235): cafe_ccic: default to allocating DMA buffers at probe time 

By default, we allocate DMA buffers when actually reading from the video
capture device.  On a system with 128MB or 256MB of ram, it's very easy
for that memory to quickly become fragmented.  We've had users report
having 30+MB of memory free, but the cafe_ccic driver is still unable to
allocate DMA buffers.

Our workaround has been to make use of the 'alloc_bufs_at_load' parameter
to allocate DMA buffers during device probing.  This patch makes DMA
buffer allocation happen during device probe by default, and changes
the parameter to 'alloc_bufs_at_read'.  The camera hardware is there,
if the cafe_ccic driver is enabled/loaded it should do its best to ensure
that the camera is actually usable; delaying DMA buffer allocation
saves an insignicant amount of memory, and causes the driver to be much
less useful.

Signed-off-by: Andres Salomon <dilinger@debian.org>
Acked-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
This commit is contained in:
Andres Salomon 2007-09-19 02:44:18 -03:00 committed by Mauro Carvalho Chehab
parent 4562fbeac6
commit 23869e2368
1 changed files with 9 additions and 9 deletions
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18
drivers/media/video/cafe_ccic.c
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@ -62,13 +62,13 @@ MODULE_SUPPORTED_DEVICE("Video");
*/
#define MAX_DMA_BUFS 3
static int alloc_bufs_at_load = 0;
module_param(alloc_bufs_at_load, bool, 0444);
MODULE_PARM_DESC(alloc_bufs_at_load,
"Non-zero value causes DMA buffers to be allocated at module "
"load time. This increases the chances of successfully getting "
"those buffers, but at the cost of nailing down the memory from "
"the outset.");
static int alloc_bufs_at_read = 0;
module_param(alloc_bufs_at_read, bool, 0444);
MODULE_PARM_DESC(alloc_bufs_at_read,
"Non-zero value causes DMA buffers to be allocated when the "
"video capture device is read, rather than at module load "
"time. This saves memory, but decreases the chances of "
"successfully getting those buffers.");
static int n_dma_bufs = 3;
module_param(n_dma_bufs, uint, 0644);
@ -1502,7 +1502,7 @@ static int cafe_v4l_release(struct inode *inode, struct file *filp)
}
if (cam->users == 0) {
cafe_ctlr_power_down(cam);
if (! alloc_bufs_at_load)
if (alloc_bufs_at_read)
cafe_free_dma_bufs(cam);
}
mutex_unlock(&cam->s_mutex);
@ -2161,7 +2161,7 @@ static int cafe_pci_probe(struct pci_dev *pdev,
/*
* If so requested, try to get our DMA buffers now.
*/
if (alloc_bufs_at_load) {
if (!alloc_bufs_at_read) {
if (cafe_alloc_dma_bufs(cam, 1))
cam_warn(cam, "Unable to alloc DMA buffers at load"
" will try again later.");