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aes2501: Harden against low finger pressure

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Wait for 3 empty frames before stopping the scan

The driver used to stop the scan immediately after an empty frame
(by checking for hist sum == 0), but it is possible to get empty
frames in the middle of the scan due to low finger pressure.
Waiting for 3 empty frames stop the driver wrongly aborting the scan
too early.

https://bugs.freedesktop.org/show_bug.cgi?id=56715
This commit is contained in:
Vasily Khoruzhick 2012-11-03 16:08:04 +03:00 committed by Bastien Nocera
parent 84b97ea15b
commit d8aae30a67
1 changed files with 23 additions and 18 deletions
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29
libfprint/drivers/aes2501.c
View file

@ -67,6 +67,7 @@ struct aes2501_dev {
GSList *strips;
size_t strips_len;
gboolean deactivating;
int no_finger_cnt;
};
typedef void (*aes2501_read_regs_cb)(struct fp_img_dev *dev, int status,
@ -559,12 +560,6 @@ static void capture_read_strip_cb(struct libusb_transfer *transfer)
goto out;
}
/* FIXME: would preallocating strip buffers be a decent optimization? */
stripdata = g_malloc(192 * 8);
memcpy(stripdata, data + 1, 192*8);
aesdev->strips = g_slist_prepend(aesdev->strips, stripdata);
aesdev->strips_len++;
threshold = regval_from_dump(data + 1 + 192*8 + 1 + 16*2 + 1 + 8,
AES2501_REG_DATFMT);
if (threshold < 0) {
@ -579,20 +574,29 @@ static void capture_read_strip_cb(struct libusb_transfer *transfer)
}
fp_dbg("sum=%d", sum);
/* FIXME: 0 might be too low as a threshold */
/* FIXME: sometimes we get 0 in the middle of a scan, should we wait for
* a few consecutive zeroes? */
/* FIXME: we should have an upper limit on the number of strips */
/* If sum is 0, finger has been removed */
/* Sum is 0, maybe finger was removed? Wait for 3 empty frames
* to ensure
*/
if (sum == 0) {
aesdev->no_finger_cnt++;
if (aesdev->no_finger_cnt == 3) {
/* assemble image and submit it to library */
assemble_and_submit_image(dev);
fpi_imgdev_report_finger_status(dev, FALSE);
/* marking machine complete will re-trigger finger detection loop */
fpi_ssm_mark_completed(ssm);
} else {
fpi_ssm_jump_to_state(ssm, CAPTURE_REQUEST_STRIP);
}
} else {
/* obtain next strip */
/* FIXME: would preallocating strip buffers be a decent optimization? */
stripdata = g_malloc(192 * 8);
memcpy(stripdata, data + 1, 192*8);
aesdev->no_finger_cnt = 0;
aesdev->strips = g_slist_prepend(aesdev->strips, stripdata);
aesdev->strips_len++;
fpi_ssm_jump_to_state(ssm, CAPTURE_REQUEST_STRIP);
}
@ -677,6 +681,7 @@ static void start_capture(struct fp_img_dev *dev)
return;
}
aesdev->no_finger_cnt = 0;
ssm = fpi_ssm_new(dev->dev, capture_run_state, CAPTURE_NUM_STATES);
fp_dbg("");
ssm->priv = dev;