Re: [PATCH 1/1] V4L: stk11xx, add a new webcam driver

[Mauro Carvalho Chehab <mchehab@infradead.org>]

Hi Jiri,

I have some comments for your driver.

> + * Copyright (C) Nicolas VIVIEN

It would be interesting to have Nicolas SOB as well, if possible.

> +
> +#ifndef CONFIG_STK11XX_DEBUG_STREAM
> +#define CONFIG_STK11XX_DEBUG_STREAM	0
> +#endif
> +
> +#if CONFIG_STK11XX_DEBUG_STREAM

I would instead use:
#ifdef CONFIG_STK11XX_DEBUG_STREAM

> +/*
> + * Bayer conversion
> + */

We don't do format conversions in kernel. Instead, you should return a
proper Bayer Fourcc format (like V4L2_PIX_FMT_SBGGR8).

> +static void stk11xx_resize_image(u8 *out, const u8 *in,
> +		unsigned int width, unsigned int height, unsigned int factor)

Also, kernel shouldn't be doing image resize.

> +static int stk11xx_decompress(struct stk11xx *dev)
> +{

We don't do format conversions in kernel. Instead, you should return a
proper Bayer Fourcc format (like V4L2_PIX_FMT_SBGGR8).

> +static int stk1125_load_microcode(struct stk11xx *dev)
> +{
> +	unsigned int i;
> +	const u8 *values_204, *values_205;
> +	int retok, value;
> +
> +	/* From 80x60 to 640x480 */
> +	const u8 values_1_204[] = {
> +		0x12, 0x11, 0x3b, 0x6a, 0x13, 0x10, 0x00, 0x01, 0x02, 0x13,
> +		0x39, 0x38, 0x37, 0x35, 0x0e, 0x12, 0x04, 0x0c, 0x0d, 0x17,
> +		0x18, 0x32, 0x19, 0x1a, 0x03, 0x1b, 0x16, 0x33, 0x34, 0x41,
> +		0x96, 0x3d, 0x69, 0x3a, 0x8e, 0x3c, 0x8f, 0x8b, 0x8c, 0x94,
> +		0x95, 0x40, 0x29, 0x0f, 0xa5, 0x1e, 0xa9, 0xaa, 0xab, 0x90,
> +		0x91, 0x9f, 0xa0, 0x24, 0x25, 0x26, 0x14, 0x2a, 0x2b
> +	};
> +	const u8 values_1_205[] = {
> +		0x45, 0x80, 0x01, 0x7d, 0x80, 0x00, 0x00, 0x80, 0x80, 0x80,
> +		0x50, 0x93, 0x00, 0x81, 0x20, 0x45, 0x00, 0x00, 0x00, 0x24,
> +		0xc4, 0xb6, 0x00, 0x3c, 0x36, 0x00, 0x07, 0xe2, 0xbf, 0x00,
> +		0x04, 0x19, 0x40, 0x0d, 0x00, 0x73, 0xdf, 0x06, 0x20, 0x88,
> +		0x88, 0xc1, 0x3f, 0x42, 0x80, 0x04, 0xb8, 0x92, 0x0a, 0x00,
> +		0x00, 0x00, 0x00, 0x68, 0x5c, 0xc3, 0x2e, 0x00, 0x00
> +	};
> +
> +	/* From 800x600 to 1280x1024 */
> +	const u8 values_2_204[] = {
> +		0x12, 0x11, 0x3b, 0x6a, 0x13, 0x10, 0x00, 0x01, 0x02, 0x13,
> +		0x39, 0x38, 0x37, 0x35, 0x0e, 0x12, 0x04, 0x0c, 0x0d, 0x17,
> +		0x18, 0x32, 0x19, 0x1a, 0x03, 0x1b, 0x16, 0x33, 0x34, 0x41,
> +		0x96, 0x3d, 0x69, 0x3a, 0x8e, 0x3c, 0x8f, 0x8b, 0x8c, 0x94,
> +		0x95, 0x40, 0x29, 0x0f, 0xa5, 0x1e, 0xa9, 0xaa, 0xab, 0x90,
> +		0x91, 0x9f, 0xa0, 0x24, 0x25, 0x26, 0x14, 0x2a, 0x2b
> +	};
> +	const u8 values_2_205[] = {
> +		0x05, 0x80, 0x01, 0x7d, 0x80, 0x00, 0x00, 0x80, 0x80, 0x80,
> +		0x50, 0x93, 0x00, 0x81, 0x20, 0x05, 0x00, 0x00, 0x00, 0x1b,
> +		0xbb, 0xa4, 0x01, 0x81, 0x12, 0x00, 0x07, 0xe2, 0xbf, 0x00,
> +		0x04, 0x19, 0x40, 0x0d, 0x00, 0x73, 0xdf, 0x06, 0x20, 0x88,
> +		0x88, 0xc1, 0x3f, 0x42, 0x80, 0x04, 0xb8, 0x92, 0x0a, 0x00,
> +		0x00, 0x00, 0x00, 0x68, 0x5c, 0xc3, 0x2e, 0x00, 0x00
> +	};

Please use instead the load_firmware routines. It is not a good idea to
have firmware inside the kernel. Also, this might rise some legal issues
due to licensing models.

> +
> +/* 
> + * The configuration of device is composed of 11 steps.
> + * This function is called by the initialization process.
> + *
> + * We don't know the meaning of these steps! We only replay the USB log.
> + *
> + * The steps 0 to 9 are called during the initialization.
> + * Then, the driver choose the last step :
> + *   10 : for a resolution from 80x60 to 640x480 
> + *   11 : for a resolution from 800x600 to 1280x1024
> + */
> +static int stk1125_configure_device(struct stk11xx *dev, int step)
> +{
> +	int value;
> +
> +	/*      0,    1,    2,    3,    4,    5,    6,    7,    8,    9, 
> +		    10,   11 */
> +
> +	const u8 values_001B[] = {
> +		0x0E, 0x03, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E,
> +		    0x0E, 0x0E
> +	};
> +	const u8 values_001C[] = {
> +		0x06, 0x02, 0x46, 0x46, 0x46, 0x46, 0x46, 0x46, 0x46, 0x46,
> +		    0x46, 0x0E
> +	};
> +	const u8 values_0202[] = {
> +		0x1E, 0x0A, 0x1E, 0x1E, 0x1E, 0x1E, 0x1E, 0x1E, 0x1E, 0x1E,
> +		    0x1E, 0x1E
> +	};
> +	const u8 values_0110[] = {
> +		0x07, 0x00, 0x00, 0x00, 0x00, 0x3E, 0x3E, 0x00, 0x00, 0x00,
> +		    0x00, 0x00
> +	};
> +	const u8 values_0112[] = {
> +		0x07, 0x00, 0x00, 0x00, 0x00, 0x09, 0x09, 0x00, 0x00, 0x00,
> +		    0x00, 0x00
> +	};
> +	const u8 values_0114[] = {
> +		0x87, 0x80, 0x80, 0x80, 0x80, 0xBE, 0xBE, 0x80, 0x80, 0x80,
> +		    0x80, 0x00
> +	};
> +	const u8 values_0115[] = {
> +		0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02,
> +		    0x02, 0x05
> +	};
> +	const u8 values_0116[] = {
> +		0xE7, 0xE0, 0xE0, 0xE0, 0xE0, 0xE9, 0xE9, 0xE0, 0xE0, 0xE0,
> +		    0xE0, 0x00
> +	};
> +	const u8 values_0117[] = {
> +		0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
> +		    0x01, 0x04
> +	};
> +	const u8 values_0100[] = {
> +		0x20, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21,
> +		    0x21, 0x21
> +	};
> +
> +	dev_dbg(&dev->udev->dev, "stk1125_configure_device: %d\n", step);
> +
> +	stk11xx_write_registry(dev, 0x0000, 0x0024);
> +	stk11xx_write_registry(dev, 0x0002, 0x0068);
> +	stk11xx_write_registry(dev, 0x0003, 0x0080);
> +	stk11xx_write_registry(dev, 0x0005, 0x0000);
	...

Instead of using all those write, you should consider creating a table
of values and use something like:
	stk11xx_write_regs(dev, table1);

> +/*
> + * STK-1135 API
> + */
> +
> +static int stk1135_load_microcode(struct stk11xx *dev)
> +{
> +	unsigned int i;
> +	int retok, value;

> +
> +	const u8 values_204[] = {
> +		0x17, 0x19, 0xb4, 0xa6, 0x12, 0x13, 0x1e, 0x21, 0x24, 0x32,
> +		0x36, 0x39, 0x4d, 0x53, 0x5d, 0x5f, 0x60, 0x61, 0x62, 0x63,
> +		0x64, 0x65, 0x66, 0x82, 0x83, 0x85, 0x86, 0x89, 0x97, 0x98,
> +		0xad, 0xae, 0xb8, 0xb9, 0xba, 0xbb, 0xbc, 0xbf, 0x48, 0xd8,
> +		0x76, 0x77, 0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f,
> +		0x80, 0x81, 0xd8, 0x76, 0x77, 0x78, 0x79, 0x7a, 0x7b, 0x7c,
> +		0x7d, 0x7e, 0x7f, 0x80, 0x81, 0xd8, 0x76, 0x77, 0x78, 0x79,
> +		0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f, 0x80, 0x81, 0x5c, 0xc0,
> +		0x59, 0x5a, 0x5b, 0xd4, 0x8e, 0x8f, 0x90, 0x91, 0x92, 0x93,
> +		0x94, 0x95, 0x96, 0xb3, 0x73, 0x06, 0x07, 0x0b, 0x15, 0x20,
> +		0x4e, 0x4f, 0x49, 0x4a, 0x4b, 0x4c, 0x46, 0x06, 0x07, 0xb9,
> +		0xba, 0xbb, 0xbc, 0x61, 0x62, 0x65, 0x66
> +	};
> +	const u8 values_205[] = {
> +		0x41, 0x41, 0x03, 0x06, 0x06, 0x08, 0x06, 0x00, 0x02, 0x69,
> +		0x35, 0x60, 0xfe, 0x1c, 0x04, 0x08, 0x08, 0x08, 0x08, 0x00,
> +		0x00, 0x10, 0x14, 0x01, 0x80, 0x0c, 0xb6, 0x00, 0x25, 0x25,
> +		0x3f, 0x24, 0x10, 0x07, 0xcc, 0x1f, 0x30, 0x02, 0x9c, 0x80,
> +		0x00, 0x0d, 0x18, 0x22, 0x2c, 0x3e, 0x4f, 0x6f, 0x8e, 0xac,
> +		0xc8, 0xe5, 0xa0, 0x00, 0x0d, 0x18, 0x22, 0x2c, 0x3e, 0x4f,
> +		0x6f, 0x8e, 0xac, 0xc8, 0xe5, 0xc0, 0x00, 0x0d, 0x18, 0x22,
> +		0x2c, 0x3e, 0x4f, 0x6f, 0x8e, 0xac, 0xc8, 0xe5, 0x70, 0x18,
> +		0x09, 0x07, 0x07, 0x3c, 0x3d, 0x95, 0x88, 0x89, 0x47, 0x9c,
> +		0x81, 0x9c, 0x3d, 0x76, 0x76, 0x01, 0xf3, 0x05, 0x00, 0x44,
> +		0x06, 0x0a, 0x96, 0x00, 0x7d, 0x00, 0x20, 0x01, 0xf3, 0x04,
> +		0xe4, 0x09, 0xc8, 0x08, 0x08, 0x10, 0x14
> +	};

Same as commented before about microcode.

You may also consider writing a separate c file for stk1135. Having a
large .c file is not very nice. The better is to split the code into a
few parts.
> +static void *stk11xx_rvmalloc(unsigned long size)

Another rvmalloc implementation? You should consider using the one
already at kernel.

> +
> +static void stk11xx_rvfree(void *mem, unsigned long size)

same as above.

> +	cap->version = (u32)DRIVER_VERSION_NUM;

You should use, instead, KERNEL_VERSION macro.

> +       /* Create frame buffers and make circular ring */
> +       for (i = 0; i < default_nbrframebuf; i++)
> +               if (dev->framebuf[i].data == NULL) {
> +                       dev->framebuf[i].data = vmalloc(STK11XX_FRAME_SIZE); 

STK11XX_FRAME_SIZE is defined previously as  (1280 * 1024 * 3). Why to
allocate so much memory, even if the user selects a lower format? You
should, instead, allocate memory dynamically as needed by the user.

> +static int stk11xx_querystd(struct file *file, void *fh, v4l2_std_id
> *a)
> +{
> +	*a = V4L2_STD_UNKNOWN;
> +	return 0;
> +}
> +
> +static int stk11xx_s_std(struct file *file, void *fh, v4l2_std_id *a)
> +{
> +	return *a == V4L2_STD_UNKNOWN ? 0 : -EINVAL;
> +}

This raises an interesting discussion about video standards. I would,
instead, use V4L2_STD_ALL, since webcams are capable of properly
handling on 525 raw lines/60Hz based standards (those derived from
640x480 res) as well as 625 raw lines/50Hz based standards (those
derived from ITU-T CIF resolutions).

As reference, STD_ALL is defined as:

#define V4L2_STD_ALL            (V4L2_STD_525_60        |\
                                 V4L2_STD_625_50)

---

Also, I noticed that several hexadecimal values are using uppercases.
The better is to convert all of them to lowercase, to keep the same
codingstyle as the other drivers.

-- 
Cheers,
Mauro