Investigating Duplex Issues

[QORTEC]

Due to issues #11 and #22, I've tested printing on both pdewacht and Owl-Maintain:

• Tested all 9 setting variations for Duplex in both CUPS and Firefox.
• Test pages are 48-49 of the Command Reference Guide for Software Developers.
• Tested with a Brother HL-2270DW

Operating System	Solus 4.6
Desktop Environment	KDE 6.2.5
Firefox Version	134.0 (64-bit)
CUPS Version	2.4.11

---

pdewacht:

brlaser Version:	v6
brlaser Commit:	23117fe
Built Locally:	Yes

$ eopkg info brlaser
Installed package:
Name                : brlaser, version: 6, release: 0
Summary             : Open-source CUPS driver for monochrome Brother laser printers
Description         : brlaser is an open-source CUPS driver designed specifically for Brother monochrome laser printers and multi-function devices
Licenses            : GPL-2.0-or-later
Component           : drivers.printer
Dependencies        : glibc libgcc cups libstdc++ ghostscript 
Distribution        : Solus, Dist. Release: 1
Architecture        : x86_64, Installed Size: 257.00 KB
Reverse Dependencies: 

Results:

Run	Cups Setting	Firefox Setting	Result	Pages
P1	Duplex Off	Duplex Off	Long	1-2
P2	Duplex Off	Duplex Long	Short	3-4
P3	Duplex Off	Duplex Short	Short	5-6
P4	Duplex Long	Duplex Off	Long	7-8
P5	Duplex Long	Duplex Long	Short	9-10
P6	Duplex Long	Duplex Short	Short	11-12
P7	Duplex Short	Duplex Off	Long	13-14
P8	Duplex Short	Duplex Long	Short	15-16
P9	Duplex Short	Duplex Short	Short	17-18

When printing with this driver, all the printed pages resulted in either Duplex Long-edge or Duplex Short-edge. I was unable to print non-duplex.

The printer would print Duplex Long-edge only when the Firefox Two-Sided printing setting was Off, while the other settings (Flip on long edge/Flip on short edge) would print Duplex Short-edge.

---

Owl-Maintain:

brlaser Version:	v6.2.6
brlaser Commit:	0ee2128
Built Locally:	No

$ eopkg info brlaser
Installed package:
Name                : brlaser, version: 6.2.6, release: 4
Summary             : Open-source CUPS driver for monochrome Brother laser printers
Description         : brlaser is an open-source CUPS driver designed specifically for Brother monochrome laser printers and multi-function devices
Licenses            : GPL-2.0-or-later
Component           : drivers.printer
Dependencies        : libstdc++ cups glibc libgcc ghostscript 
Distribution        : Solus, Dist. Release: 1
Architecture        : x86_64, Installed Size: 666.00 KB
Reverse Dependencies: 

Run	Cups Setting	Firefox Setting	Result	Pages
OM1	Duplex Off	Duplex Off	Off	1-4
OM2	Duplex Off	Duplex Long	Long	5-6
OM3	Duplex Off	Duplex Short	Short	7-8
OM4	Duplex Long	Duplex Off	Off	9-12
OM5	Duplex Long	Duplex Long	Long	13-14
OM6	Duplex Long	Duplex Short	Short	15-16
OM7	Duplex Short	Duplex Off	Off	17-20
OM8	Duplex Short	Duplex Long	Long	22-22
OM9	Duplex Short	Duplex Short	Short	22-24

When printing with this driver, the printing settings in Firefox were respected.

---

Code related to Simplex/Duplex:

Duplex was introduced in commit 7e59e61 on May 1, 2017.

Initial Printer: `DCP-7065DN`

Issues:

• Incomplete printing when using PCL &l1S

Workaround:

• Set duplex to &l2S (job.cc)
• Set Duplex to Rotated (brlaser.drv)
• Result: &l2S and Rotated functionally mimics &l1S but with extra steps/processing.

Notes:

• PCL &l1S for printing Duplex Long-edge
• PCL &l2S for printing Duplex Short-edge
• Duplex Rotated When printing Duplex Long-edge; the 2nd page will be rotated page 180 degrees

Explicit Simplex in commit d209bac on Mar 14, 2023.

Initial Printer: `HL-L2350DW`

Issues:

• The HL-L2350DW would continue to duplex even when disabled, however the reverse side is unreadable with artifacts
• The HL-2270DW also continues to duplex even when disabled, except both sides are printed correctly (Note Test Runs P1, P4 & P7)

Workaround:

• Set &l0S (job.cc)

Notes:

• PCL &l0S for printing Simplex aka (one-sided)

Tumble was introduced in commit b93c4ad on Mar 14, 2023.

Initial Printer: `HL-2300D`

Notes:

• PCL &l1S for printing Duplex Long-edge
• PCL &l2S for printing Duplex Short-edge

This commit does not take into account the CUPS drv Duplex Rotated setting.
This results in #22, where Duplex Long-edge actually prints Duplex Short-edge.
This results in #11, where the reverse side is unreadable with artifacts.

---

After investigating this issue; I've found that the Duplex Rotated setting in brlaser.drv is not being honoured on Solus. :/
This is causing the driver to appear as if it is functioning correctly; however the actual "correct" behaviour would be consistent with Issues #22 or #11.

I've confirmed that this "unexpected" behaviour is not unique to my printer (HL-2270DW). Testing the driver on Fedora resulted in an output consistent with Issue #22.

Also, I've found that the drivers behaviour is identical in both LibreOffice and Firefox; therefore it's unlikely a application specific issue.

[QORTEC]

Update:

• With the release of brlaser v6.2.7, Solus no longer duplexes correctly.
• Solus only honours the duplex PLC settings found in job.cc, ignoring the Duplex Rotated setting in brlaser.drv.
• Currently Solus only prints in Simplex or Duplex Short-edge.

Workaround:

• Revert commit fb46385.
• Optionally:
  • Replace Duplex rotated with Duplex normal:
    This change will not have a functional impact. However, if CUPS starts respecting the duplex settings in brlaser.drv, this change will minimize disruption for most users.

---

CUPS .drv (PPD):
/usr/share/cups/drv/brlaser.drv

{
  ModelName "HL-2270DW series"
  Attribute "NickName" "" "Brother HL-2270DW series, $USING"
  Attribute "1284DeviceID" "" "MFG:Brother;CMD:PJL,PCL,PCLXL;MDL:HL-2270DW series;CLS:PRINTER;CID:Brother Laser Type1;"
  Resolution k 1 0 0 0 "300dpi/300 DPI"
  Duplex rotated
  PCFileName "br2270d.ppd"
}

Duplex rotated: When printing Duplex Long-edge, the reverse side will be rotated 180 degrees.

Reference: Docs

This results in the following behavior:

• Duplex Long-edge -> Duplex Short-edge
• Duplex Short-edge -> Duplex Long-edge

CUPS Filter:
src/job.cc

if (page_params_.duplex || page_params_.tumble) {
    fputs("\033&l2S", out_);
} else {
    fputs("\033&l0S", out_);
}

• PCL &l2S is used for printing Duplex Short-edge.
• PCL &l1S is used for printing Duplex Long-edge.
• PCL &l0S is used for printing Simplex (one-sided).

Reference: PDF (pages 48–49).

---

Code Path/Logic:

• For Duplex Long-edge:
  1. Rotate the reverse side by 180 degrees.
  • Resulting output is now Short-edge.
  2. Set the printer to &l2S (Duplex Short-edge).
  • Resulting output is now Long-edge.
• For Duplex Short-edge:
  1. Set the printer to &l2S (Duplex Short-edge).
  • Resulting output is Short-edge.
• For Duplex Off:
  1. Set the printer to &l0S (Simplex).
  • Resulting output is one-sided printing.

Reason for the current Long-edge approach:

• There was an issue printing with &l1S in the past.
• I cannot test the affected printer to verify if the issue still persists.