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V4L/DVB (9646): em28xx: avoid allocating/dealocating memory on every control urb

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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>
This commit is contained in:
Mauro Carvalho Chehab 2008-11-18 14:51:08 -03:00
parent 625ff16794
commit c4a98793a6
2 changed files with 31 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

48
drivers/media/video/em28xx/em28xx-core.c
View File

@ -69,19 +69,29 @@ int em28xx_read_reg_req_len(struct em28xx *dev, u8 req, u16 reg,
int ret, byte;
if (dev->state & DEV_DISCONNECTED)
return(-ENODEV);
return -ENODEV;
if (len > URB_MAX_CTRL_SIZE)
return -EINVAL;
em28xx_regdbg("req=%02x, reg=%02x ", req, reg);
ret = usb_control_msg(dev->udev, usb_rcvctrlpipe(dev->udev, 0), req,
USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
0x0000, reg, buf, len, HZ);
0x0000, reg, dev->urb_buf, len, HZ);
if (ret < 0) {
if (reg_debug)
printk(" failed!\n");
return ret;
}
if (len)
memcpy(buf, dev->urb_buf, len);
if (reg_debug) {
printk(ret < 0 ? " failed!\n" : "%02x values: ", ret);
printk("%02x values: ", ret);
for (byte = 0; byte < len; byte++)
printk(" %02x", (unsigned char)buf[byte]);
printk("\n");
}
@ -104,14 +114,16 @@ int em28xx_read_reg_req(struct em28xx *dev, u8 req, u16 reg)
ret = usb_control_msg(dev->udev, usb_rcvctrlpipe(dev->udev, 0), req,
USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
0x0000, reg, &val, 1, HZ);
0x0000, reg, dev->urb_buf, 1, HZ);
if (ret < 0) {
printk(" failed!\n");
return ret;
}
val = dev->urb_buf[0];
if (reg_debug)
printk(ret < 0 ? " failed!\n" :
"%02x\n", (unsigned char) val);
if (ret < 0)
return ret;
printk("%02x\n", (unsigned char) val);
return val;
}
@ -130,19 +142,13 @@ int em28xx_write_regs_req(struct em28xx *dev, u8 req, u16 reg, char *buf,
{
int ret;
/*usb_control_msg seems to expect a kmalloced buffer */
unsigned char *bufs;
if (dev->state & DEV_DISCONNECTED)
return -ENODEV;
if (len < 1)
if ((len < 1) || (len > URB_MAX_CTRL_SIZE))
return -EINVAL;
bufs = kmalloc(len, GFP_KERNEL);
em28xx_regdbg("req=%02x reg=%02x:", req, reg);
if (reg_debug) {
int i;
for (i = 0; i < len; ++i)
@ -150,16 +156,14 @@ int em28xx_write_regs_req(struct em28xx *dev, u8 req, u16 reg, char *buf,
printk("\n");
}
if (!bufs)
return -ENOMEM;
memcpy(bufs, buf, len);
memcpy(dev->urb_buf, buf, len);
ret = usb_control_msg(dev->udev, usb_sndctrlpipe(dev->udev, 0), req,
USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
0x0000, reg, bufs, len, HZ);
0x0000, reg, dev->urb_buf, len, HZ);
if (dev->wait_after_write)
msleep(dev->wait_after_write);
kfree(bufs);
return ret;
}

5
drivers/media/video/em28xx/em28xx.h
View File

@ -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 @@ struct em28xx {
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);