Merge branch 'genesys-canon-4400f' into 'master'

Fix flatbed scans on Canon 4400F

See merge request sane-project/backends!341

backend/genesys/gl843.cpp

@@ -1928,6 +1928,12 @@ void CommandSetGl843::offset_calibration(Genesys_Device* dev, const Genesys_Sens
         target_pixels = static_cast<int>((size * resolution) / MM_PER_INCH);
     }
 
+    if (dev->model->model_id == ModelId::CANON_4400F &&
+        dev->settings.scan_method == ScanMethod::FLATBED)
+    {
+        return;
+    }
+
     ScanFlag flags = ScanFlag::DISABLE_SHADING |
                      ScanFlag::DISABLE_GAMMA |
                      ScanFlag::SINGLE_LINE |

backend/genesys/tables_model.cpp

@@ -430,7 +430,7 @@ void genesys_init_usb_device_tables()
     model.x_size = 215.9;
     model.y_size = 297.0;
 
-    model.y_offset_calib_white = 0.0;
+    model.y_offset_calib_white = 2.0;
     model.y_size_calib_mm = 4.0;
     model.x_offset_calib_black = 0.0;