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aes2501: write multiple registers simultaneously

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Instead of writing each register in a separate USB transaction, we now
write up to 16 at once.

This drastically improves scan image quality due to reducing the amount of
time needed per iteration of the sampling loop (sending 1 USB transaction
per iteration instead of 7).
This commit is contained in:
Daniel Drake 2007-11-16 15:35:48 +00:00
parent bfc55c4f0f
commit be0e9debd9
1 changed files with 43 additions and 12 deletions
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55
libfprint/drivers/aes2501.c
View file

@ -36,6 +36,7 @@
#define EP_OUT (2 | USB_ENDPOINT_OUT)
#define BULK_TIMEOUT 4000
#define MAX_REGWRITES_PER_REQUEST 16
/*
* The AES2501 is an imaging device using a swipe-type sensor. It samples
@ -61,19 +62,27 @@ struct aes2501_regwrite {
unsigned char value;
};
static int write_reg(struct fp_img_dev *dev, unsigned char reg,
unsigned char value)
static int do_write_regv(struct fp_img_dev *dev, struct aes2501_regwrite *regs,
unsigned int num)
{
unsigned char data[] = { reg, value };
size_t alloc_size = num * 2;
unsigned char *data = g_malloc(alloc_size);
unsigned int i;
size_t offset = 0;
int r;
fp_dbg("%02x=%02x", reg, value);
r = usb_bulk_write(dev->udev, EP_OUT, data, sizeof(data), BULK_TIMEOUT);
for (i = 0; i < num; i++) {
data[offset++] = regs[i].reg;
data[offset++] = regs[i].value;
}
r = usb_bulk_write(dev->udev, EP_OUT, data, alloc_size, BULK_TIMEOUT);
g_free(data);
if (r < 0) {
fp_err("bulk write error %d", r);
return r;
} else if (r < sizeof(data)) {
fp_err("unexpected short write %d/%d", r, sizeof(data));
} else if (r < alloc_size) {
fp_err("unexpected short write %d/%d", r, alloc_size);
return -EIO;
}
@ -84,15 +93,27 @@ static int write_regv(struct fp_img_dev *dev, struct aes2501_regwrite *regs,
unsigned int num)
{
unsigned int i;
int r;
int skip = 0;
int add_offset = 0;
fp_dbg("write %d regs", num);
/* FIXME: could combine multiple writes into a single transaction */
for (i = 0; i < num; i += add_offset + skip) {
int r, j;
int limit = MIN(num, i + MAX_REGWRITES_PER_REQUEST);
skip = 0;
for (i = 0; i < num; i++) {
r = write_reg(dev, regs[i].reg, regs[i].value);
for (j = i; j < limit; j++)
if (!regs[j].reg) {
skip = 1;
break;
}
add_offset = j - i;
r = do_write_regv(dev, &regs[i], add_offset);
if (r < 0)
return r;
}
return 0;
}
@ -115,9 +136,13 @@ static int read_data(struct fp_img_dev *dev, unsigned char *data, size_t len)
static int read_regs(struct fp_img_dev *dev, unsigned char *data)
{
int r;
const struct aes2501_regwrite regwrite = {
AES2501_REG_CTRL2, AES2501_CTRL2_READ_REGS
};
fp_dbg("");
r = write_reg(dev, AES2501_REG_CTRL2, AES2501_CTRL2_READ_REGS);
r = write_regv(dev, &regwrite, 1);
if (r < 0)
return r;
@ -126,6 +151,7 @@ static int read_regs(struct fp_img_dev *dev, unsigned char *data)
static const struct aes2501_regwrite init_1[] = {
{ AES2501_REG_CTRL1, AES2501_CTRL1_MASTER_RESET },
{ 0, 0 },
{ 0xb0, 0x27 }, /* Reserved? */
{ AES2501_REG_CTRL1, AES2501_CTRL1_MASTER_RESET },
{ AES2501_REG_EXCITCTRL, 0x40 },
@ -304,6 +330,7 @@ static const struct aes2501_regwrite finger_det_reqs[] = {
{ 0xa7, 0x00 },
{ AES2501_REG_TREGC, AES2501_TREGC_ENABLE },
{ AES2501_REG_TREGD, 0x1a },
{ 0, 0 },
{ AES2501_REG_CTRL1, AES2501_CTRL1_REG_UPDATE },
{ AES2501_REG_CTRL2, AES2501_CTRL2_SET_ONE_SHOT },
{ AES2501_REG_LPONT, AES2501_LPONT_MIN_VALUE },
@ -460,6 +487,7 @@ static unsigned int assemble(unsigned char *input, unsigned char *output,
static const struct aes2501_regwrite capture_reqs_1[] = {
{ AES2501_REG_CTRL1, AES2501_CTRL1_MASTER_RESET },
{ 0, 0 },
{ AES2501_REG_EXCITCTRL, 0x40 },
{ AES2501_REG_DETCTRL,
AES2501_DETCTRL_SDELAY_31_MS | AES2501_DETCTRL_DRATE_CONTINUOUS },
@ -590,6 +618,9 @@ static int capture(struct fp_img_dev *dev, gboolean unconditional,
if (r_errors_sum > errors_sum) {
img->height = assemble(img->data, cooked, nstrips, FALSE, &errors_sum);
img->flags |= FP_IMG_V_FLIPPED | FP_IMG_H_FLIPPED;
fp_dbg("normal scan direction");
} else {
fp_dbg("reversed scan direction");
}
for (i = 0; i < img->height * FRAME_WIDTH; i++)