V4L/DVB (9646): em28xx: avoid allocating/dealocating memory on every control urb
Before this patch, every register setup on em28xx were dynamically
allocating a temporary buffer for control URB's to be handled.
To avoid this ping-pong, use, instead a pre-allocated buffer.
Also, be sure that read control URB's also use the buffer, instead of
relying on a stack buffer.
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/drivers/media/video/em28xx/em28xx.h b/drivers/media/video/em28xx/em28xx.h
index 8278117..1adf3d9 100644
--- a/drivers/media/video/em28xx/em28xx.h
+++ b/drivers/media/video/em28xx/em28xx.h
@@ -102,6 +102,9 @@
#define EM28XX_MIN_BUF 4
#define EM28XX_DEF_BUF 8
+/*Limits the max URB message size */
+#define URB_MAX_CTRL_SIZE 80
+
/* Params for validated field */
#define EM28XX_BOARD_NOT_VALIDATED 1
#define EM28XX_BOARD_VALIDATED 0
@@ -451,6 +454,8 @@
unsigned int *alt_max_pkt_size; /* array of wMaxPacketSize */
struct urb *urb[EM28XX_NUM_BUFS]; /* urb for isoc transfers */
char *transfer_buffer[EM28XX_NUM_BUFS]; /* transfer buffers for isoc transfer */
+ char urb_buf[URB_MAX_CTRL_SIZE]; /* urb control msg buffer */
+
/* helper funcs that call usb_control_msg */
int (*em28xx_write_regs) (struct em28xx *dev, u16 reg,
char *buf, int len);