[sane-devel] [PATCH] Progress on HP2400 (genesys backend)

[Alexey Osipov]

Hi, dear SANE developers!

Proposed patch enable support of 50/150/600dpi Color/Gray/LineArt modes
for Hewlett-Packard ScanJet 2400 scanner.

This was made by parsing UsbSnoop logs with stef's scripts (thank you!).

100/300dpi modes were already good, so I didn't touch them.

I have also refined sensor and motor values for 1200dpi modes, but there
are some problems with them.

Here is a list of remaining problems I can't solve:

1. 1200dpi Gray mode works, but the resulting image is interlaced
vertically with black one-pixel width lines. Why this can happen?
Example: http://lion-simba.github.com/1200dpi_gray_lines.tiff

2. 1200dpi Color mode works, but very slow. Scanner warm-up and
calibration takes approx 5 mins before head even moves. Then, when
scanning begins, head moves forward and backward each few lines. I have
made timestamped logs of this situation (truncated log attached). You can see -
problem is in "gl646_bulk_read_data" which regularly hangs for approx 10
seconds like this:

during warm-up and calibration:
---------------------
1307470777: [genesys_gl646] gl646_bulk_read_data: trying to read 65472 bytes of data
1307470778: [genesys_gl646] gl646_bulk_read_data read 65472 bytes, 679896 remaining
1307470778: [genesys_gl646] gl646_bulk_read_data: trying to read 65472 bytes of data
1307470778: [genesys_gl646] gl646_bulk_read_data read 65472 bytes, 614424 remaining
1307470778: [genesys_gl646] gl646_bulk_read_data: trying to read 65472 bytes of data
[9 seconds delay]
1307470787: [genesys_gl646] gl646_bulk_read_data read 65472 bytes, 548952 remaining
1307470787: [genesys_gl646] gl646_bulk_read_data: trying to read 65472 bytes of data
1307470787: [genesys_gl646] gl646_bulk_read_data read 65472 bytes, 483480 remaining
---------------------

during scan:
---------------------
1307471061: [genesys_gl646] gl646_bulk_read_data: requesting 30464 bytes
1307471061: [genesys_gl646] gl646_bulk_read_data: trying to read 30464 bytes of data
[9 seconds delay]
1307471070: [genesys_gl646] gl646_bulk_read_data read 30464 bytes, 0 remaining
1307471070: [genesys_gl646] gl646_bulk_read_data: end
---------------------

Any ideas of what is wrong? Proprietary driver running on the same
system scan well in 1200dpi Color, so I think this is not libusb bug.
Maybe some GL646 miscofiguration?

3. In all modes, there are extra pixels to the left of the image, which
are beyond of glass window of scanner. Meanwhile, right side of image is
cropped by (i guess) same number of pixels. I think it can be fixed by
tuning CCD_start_xoffset/dummy_pixel/sensor_pixels in Genesys_Sensor,
but I'm unsure what is for exactly? What is dummy_pixel?

Regards,
Alexey.


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