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Commit 23869e23 authored by Andres Salomon's avatar Andres Salomon Committed by Mauro Carvalho Chehab
Browse files

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: default avatarAndres Salomon <dilinger@debian.org>
Acked-by: default avatarJonathan Corbet <corbet@lwn.net>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@infradead.org>
parent 4562fbea

drivers/media/video/cafe_ccic.c

+9 −9
Original line number Diff line number Diff line
@@ -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.");