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>
diff --git a/drivers/media/video/cafe_ccic.c b/drivers/media/video/cafe_ccic.c
index 0fae0e0..ccb3700 100644
--- a/drivers/media/video/cafe_ccic.c
+++ b/drivers/media/video/cafe_ccic.c
@@ -62,13 +62,13 @@
*/
#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 @@
}
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 @@
/*
* 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.");