drivers/media/usb/gspca/sq905c.c

Source file repositories/reference/linux-study-clean/drivers/media/usb/gspca/sq905c.c

File Facts

System
Linux kernel
Corpus path
drivers/media/usb/gspca/sq905c.c
Extension
.c
Size
9363 bytes
Lines
331
Domain
Driver Families
Bucket
drivers/media
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

struct sd {
	struct gspca_dev gspca_dev;	/* !! must be the first item */
	const struct v4l2_pix_format *cap_mode;
	/* Driver stuff */
	struct work_struct work_struct;
	struct workqueue_struct *work_thread;
};

/*
 * Most of these cameras will do 640x480 and 320x240. 160x120 works
 * in theory but gives very poor output. Therefore, not supported.
 * The 0x2770:0x9050 cameras have max resolution of 320x240.
 */
static struct v4l2_pix_format sq905c_mode[] = {
	{ 320, 240, V4L2_PIX_FMT_SQ905C, V4L2_FIELD_NONE,
		.bytesperline = 320,
		.sizeimage = 320 * 240,
		.colorspace = V4L2_COLORSPACE_SRGB,
		.priv = 0},
	{ 640, 480, V4L2_PIX_FMT_SQ905C, V4L2_FIELD_NONE,
		.bytesperline = 640,
		.sizeimage = 640 * 480,
		.colorspace = V4L2_COLORSPACE_SRGB,
		.priv = 0}
};

/* Send a command to the camera. */
static int sq905c_command(struct gspca_dev *gspca_dev, u16 command, u16 index)
{
	int ret;

	ret = usb_control_msg(gspca_dev->dev,
			      usb_sndctrlpipe(gspca_dev->dev, 0),
			      USB_REQ_SYNCH_FRAME,                /* request */
			      USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
			      command, index, NULL, 0,
			      SQ905C_CMD_TIMEOUT);
	if (ret < 0) {
		pr_err("%s: usb_control_msg failed (%d)\n", __func__, ret);
		return ret;
	}

	return 0;
}

static int sq905c_read(struct gspca_dev *gspca_dev, u16 command, u16 index,
		       int size)
{
	int ret;

	ret = usb_control_msg(gspca_dev->dev,
			      usb_rcvctrlpipe(gspca_dev->dev, 0),
			      USB_REQ_SYNCH_FRAME,		/* request */
			      USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
			      command, index, gspca_dev->usb_buf, size,
			      SQ905C_CMD_TIMEOUT);
	if (ret < 0) {
		pr_err("%s: usb_control_msg failed (%d)\n", __func__, ret);
		return ret;
	}

	return 0;
}

/*
 * This function is called as a workqueue function and runs whenever the camera
 * is streaming data. Because it is a workqueue function it is allowed to sleep
 * so we can use synchronous USB calls. To avoid possible collisions with other
 * threads attempting to use gspca_dev->usb_buf we take the usb_lock when
 * performing USB operations using it. In practice we don't really need this
 * as the camera doesn't provide any controls.
 */
static void sq905c_dostream(struct work_struct *work)
{
	struct sd *dev = container_of(work, struct sd, work_struct);
	struct gspca_dev *gspca_dev = &dev->gspca_dev;
	int bytes_left; /* bytes remaining in current frame. */
	int data_len;   /* size to use for the next read. */
	int act_len;
	int packet_type;
	int ret;
	u8 *buffer;

	buffer = kmalloc(SQ905C_MAX_TRANSFER, GFP_KERNEL);
	if (!buffer) {
		pr_err("Couldn't allocate USB buffer\n");
		goto quit_stream;
	}

	while (gspca_dev->present && gspca_dev->streaming) {

Annotation

Implementation Notes