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Commit c4a98793 authored by Mauro Carvalho Chehab's avatar Mauro Carvalho Chehab
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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: default avatarMauro Carvalho Chehab <mchehab@redhat.com>
parent 625ff167

drivers/media/video/em28xx/em28xx-core.c

+26 −22
Original line number Diff line number Diff line
@@ -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;

	}



	if (reg_debug)

		printk(ret < 0 ? " failed!\n" :

				 "%02x\n", (unsigned char) val);

	val = dev->urb_buf[0];



	if (ret < 0)

		return ret;

	if (reg_debug)

		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;

}

drivers/media/video/em28xx/em28xx.h

+5 −0
Original line number Diff line number Diff line
@@ -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);