genesys: Use common code path to compute session num_staggered_lines

backend/genesys_gl124.cc

@@ -1071,7 +1071,6 @@ static void gl124_init_scan_regs(Genesys_Device* dev, const Genesys_Sensor& sens
   unsigned int lincnt;
     unsigned int mflags;
   int exposure_time;
-  int stagger;
 
   int dummy = 0;
   int slope_dpi = 0;
@@ -1081,20 +1080,12 @@ static void gl124_init_scan_regs(Genesys_Device* dev, const Genesys_Sensor& sens
 
     DBG (DBG_info, "%s: optical_res=%d\n", __func__, session.optical_resolution);
 
-  /* stagger */
-    if (session.ccd_size_divisor == 1 && (dev->model->flags & GENESYS_FLAG_STAGGERED_LINE)) {
-        stagger = (4 * session.params.yres) / dev->motor.base_ydpi;
-    } else {
-        stagger = 0;
-    }
-  DBG (DBG_info, "gl124_init_scan_regs : stagger=%d lines\n", stagger);
-
   /* compute scan parameters values */
   /* pixels are allways given at full optical resolution */
   /* use detected left margin and fixed value */
     start = session.params.startx;
 
-    if (stagger > 0) {
+    if (session.num_staggered_lines > 0) {
         start |= 1;
     }
 
@@ -1143,7 +1134,7 @@ static void gl124_init_scan_regs(Genesys_Device* dev, const Genesys_Sensor& sens
     max_shift = sanei_genesys_compute_max_shift(dev, session.params.channels, session.params.yres,
                                                 session.params.flags);
 
-    lincnt = session.params.lines + max_shift + stagger;
+    lincnt = session.params.lines + max_shift + session.num_staggered_lines;
 
   /* add tl_y to base movement */
     move = session.params.starty;
@@ -1172,8 +1163,8 @@ static void gl124_init_scan_regs(Genesys_Device* dev, const Genesys_Sensor& sens
   requested_buffer_size = 16 * bytes_per_line;
 
     read_buffer_size = 2 * requested_buffer_size +
-            ((max_shift + stagger) * session.optical_pixels * session.params.channels *
+            ((max_shift + session.num_staggered_lines) * session.optical_pixels *
-             session.params.depth) / 8;
+             session.params.channels * session.params.depth) / 8;
 
     dev->read_buffer.clear();
     dev->read_buffer.alloc(read_buffer_size);
@@ -1199,8 +1190,8 @@ static void gl124_init_scan_regs(Genesys_Device* dev, const Genesys_Sensor& sens
   dev->current_setup.exposure_time = exposure_time;
     dev->current_setup.xres = session.params.xres;
   dev->current_setup.ccd_size_divisor = session.ccd_size_divisor;
-  dev->current_setup.stagger = stagger;
+    dev->current_setup.stagger = session.num_staggered_lines;
-  dev->current_setup.max_shift = max_shift + stagger;
+    dev->current_setup.max_shift = max_shift + session.num_staggered_lines;
 
   dev->total_bytes_read = 0;
     if (session.params.depth == 1) {
@@ -1222,7 +1213,6 @@ gl124_calculate_current_setup (Genesys_Device * dev, const Genesys_Sensor& senso
 
   unsigned int lincnt;
   int exposure_time;
-  int stagger;
 
   int max_shift, dpihw;
 
@@ -1272,15 +1262,7 @@ gl124_calculate_current_setup (Genesys_Device * dev, const Genesys_Sensor& senso
                                                              session.ccd_size_divisor);
     dev->segnb = sensor_profile.custom_regs.get_value(0x98) & 0x0f;
 
-  /* stagger */
+    lincnt = session.params.lines + max_shift + session.num_staggered_lines;
-    if (session.ccd_size_divisor == 1 && (dev->model->flags & GENESYS_FLAG_STAGGERED_LINE)) {
-        stagger = (4 * session.params.yres) / dev->motor.base_ydpi;
-    } else {
-        stagger = 0;
-    }
-  DBG (DBG_info, "%s: stagger=%d lines\n", __func__, stagger);
-
-    lincnt = session.params.lines + max_shift + stagger;
 
     dev->session = session;
     dev->current_setup.pixels = (session.optical_pixels * session.params.xres) / sensor.optical_res;
@@ -1289,8 +1271,8 @@ gl124_calculate_current_setup (Genesys_Device * dev, const Genesys_Sensor& senso
   dev->current_setup.exposure_time = exposure_time;
     dev->current_setup.xres = session.params.xres;
   dev->current_setup.ccd_size_divisor = session.ccd_size_divisor;
-  dev->current_setup.stagger = stagger;
+    dev->current_setup.stagger = session.num_staggered_lines;
-  dev->current_setup.max_shift = max_shift + stagger;
+    dev->current_setup.max_shift = max_shift + session.num_staggered_lines;
 }
 
 /**

backend/genesys_gl646.cc

@@ -362,7 +362,7 @@ static void gl646_setup_registers(Genesys_Device* dev,
   unsigned int bpp;   /**> bytes per pixel */
   uint32_t z1, z2;
   uint16_t ex, sx;
-  int stagger, words_per_line, max_shift;
+    int words_per_line, max_shift;
   size_t requested_buffer_size;
   size_t read_buffer_size;
   SANE_Int xresolution;
@@ -565,18 +565,9 @@ static void gl646_setup_registers(Genesys_Device* dev,
   linecnt = (linecnt * motor->ydpi) / session.params.yres + max_shift;
 
   /* at QUATER_STEP lines are 'staggered' and need correction */
-  stagger = 0;
+    linecnt += session.num_staggered_lines;
-    if (session.ccd_size_divisor == 1 && (dev->model->flags & GENESYS_FLAG_STAGGERED_LINE)) {
-        // for HP3670, stagger happens only at >=1200 dpi
-        if ((dev->model->motor_type != MOTOR_HP3670 && dev->model->motor_type != MOTOR_HP2400)
-          || session.params.yres >= (unsigned) sensor.optical_res)
-	{
-            stagger = (4 * session.params.yres) / dev->motor.base_ydpi;
-	}
-    }
-  linecnt += stagger;
 
-  DBG(DBG_info, "%s :  max_shift=%d, stagger=%d lines\n", __func__, max_shift, stagger);
+  DBG(DBG_info, "%s :  max_shift=%d lines\n", __func__, max_shift);
 
   /* CIS scanners read one line per color channel
    * since gray mode use 'add' we also read 3 channels even not in
@@ -625,13 +616,12 @@ static void gl646_setup_registers(Genesys_Device* dev,
   /* move distance must be adjusted to take into account the extra lines
    * read to reorder data */
   feedl = move;
-  if (stagger + max_shift > 0 && feedl != 0)
+    if (session.num_staggered_lines + max_shift > 0 && feedl != 0) {
-    {
+        int feed_offset = ((max_shift + session.num_staggered_lines) * dev->motor.optical_ydpi) /
-      if (feedl >
+                motor->ydpi;
-	  ((max_shift + stagger) * dev->motor.optical_ydpi) / motor->ydpi)
+        if (feedl > feed_offset) {
-	feedl =
+            feedl = feedl - feed_offset;
-	  feedl -
+        }
-	  ((max_shift + stagger) * dev->motor.optical_ydpi) / motor->ydpi;
     }
 
   /* we assume all scans are done with 2 tables */
@@ -778,7 +768,8 @@ static void gl646_setup_registers(Genesys_Device* dev,
   /* we must use a round number of words_per_line */
   requested_buffer_size = 8 * words_per_line;
     read_buffer_size = 2 * requested_buffer_size +
-        ((max_shift + stagger) * session.params.pixels * session.params.channels * session.params.depth) / 8;
+        ((max_shift + session.num_staggered_lines) * session.params.pixels *
+         session.params.channels * session.params.depth) / 8;
 
     dev->read_buffer.clear();
     dev->read_buffer.alloc(read_buffer_size);
@@ -804,8 +795,8 @@ static void gl646_setup_registers(Genesys_Device* dev,
     dev->current_setup.exposure_time = sensor.exposure_lperiod;
     dev->current_setup.xres = sensor.real_resolution;
   dev->current_setup.ccd_size_divisor = session.ccd_size_divisor;
-  dev->current_setup.stagger = stagger;
+    dev->current_setup.stagger = session.num_staggered_lines;
-  dev->current_setup.max_shift = max_shift + stagger;
+    dev->current_setup.max_shift = max_shift + session.num_staggered_lines;
 
   /* total_bytes_to_read is the number of byte to send to frontend
    * total_bytes_read is the number of bytes sent to frontend

backend/genesys_gl841.cc

@@ -1767,7 +1767,6 @@ static void gl841_init_scan_regs(Genesys_Device* dev, const Genesys_Sensor& sens
   int move;
   unsigned int lincnt;
   int exposure_time;
-  int stagger;
   int avg;
 
   int slope_dpi = 0;
@@ -1804,15 +1803,6 @@ independent of our calculated values:
   dev->bytes_to_read
  */
 
-/* stagger */
-
-    if (session.ccd_size_divisor == 1 && (dev->model->flags & GENESYS_FLAG_STAGGERED_LINE)) {
-        stagger = (4 * session.params.yres) / dev->motor.base_ydpi;
-    } else {
-        stagger = 0;
-    }
-  DBG(DBG_info, "%s : stagger=%d lines\n", __func__, stagger);
-
     gl841_assert_supported_resolution(session);
 
   /* compute scan parameters values */
@@ -1824,8 +1814,9 @@ independent of our calculated values:
 
   start += sensor.dummy_pixel + 1;
 
-  if (stagger > 0)
+    if (session.num_staggered_lines > 0) {
-    start |= 1;
+        start |= 1;
+    }
 
   /* in case of SHDAREA, we need to align start
    * on pixel average factor, startx is different of
@@ -1906,7 +1897,7 @@ dummy \ scanned lines
     max_shift = sanei_genesys_compute_max_shift(dev, session.params.channels,
                                                 session.params.yres, session.params.flags);
 
-    lincnt = session.params.lines + max_shift + stagger;
+    lincnt = session.params.lines + max_shift + session.num_staggered_lines;
 
     move = session.params.starty;
   DBG(DBG_info, "%s: move=%d steps\n", __func__, move);
@@ -1948,7 +1939,8 @@ dummy \ scanned lines
     }
 
     read_buffer_size = 2 * requested_buffer_size +
-        ((max_shift + stagger) * session.optical_pixels *  session.params.channels * session.params.depth) / 8;
+        ((max_shift + session.num_staggered_lines) * session.optical_pixels *
+         session.params.channels * session.params.depth) / 8;
 
     dev->read_buffer.clear();
     dev->read_buffer.alloc(read_buffer_size);
@@ -1973,8 +1965,8 @@ dummy \ scanned lines
   dev->current_setup.exposure_time = exposure_time;
     dev->current_setup.xres = session.params.xres;
     dev->current_setup.ccd_size_divisor = session.ccd_size_divisor;
-  dev->current_setup.stagger = stagger;
+    dev->current_setup.stagger = session.num_staggered_lines;
-  dev->current_setup.max_shift = max_shift + stagger;
+    dev->current_setup.max_shift = max_shift + session.num_staggered_lines;
 
 /* TODO: should this be done elsewhere? */
   /* scan bytes to send to the frontend */
@@ -2010,7 +2002,6 @@ static void gl841_calculate_current_setup(Genesys_Device * dev, const Genesys_Se
 
   unsigned int lincnt;
   int exposure_time;
-  int stagger;
 
   int slope_dpi = 0;
   int dummy = 0;
@@ -2044,15 +2035,6 @@ static void gl841_calculate_current_setup(Genesys_Device * dev, const Genesys_Se
 
     gl841_compute_session(dev, session, sensor);
 
-/* stagger */
-
-    if (session.ccd_size_divisor == 1 && (dev->model->flags & GENESYS_FLAG_STAGGERED_LINE)) {
-        stagger = (4 * session.params.yres) / dev->motor.base_ydpi;
-    } else {
-        stagger = 0;
-    }
-  DBG(DBG_info, "%s: stagger=%d lines\n", __func__, stagger);
-
     gl841_assert_supported_resolution(session);
 
   /* compute scan parameters values */
@@ -2062,9 +2044,9 @@ static void gl841_calculate_current_setup(Genesys_Device * dev, const Genesys_Se
 
   start += sensor.dummy_pixel + 1;
 
-  if (stagger > 0) {
+    if (session.num_staggered_lines > 0) {
-    start |= 1;
+        start |= 1;
-  }
+    }
 
   /* dummy lines: may not be usefull, for instance 250 dpi works with 0 or 1
      dummy line. Maybe the dummy line adds correctness since the motor runs
@@ -2114,7 +2096,7 @@ dummy \ scanned lines
     max_shift = sanei_genesys_compute_max_shift(dev, session.params.channels,
                                                 session.params.yres, 0);
 
-    lincnt = session.params.lines + max_shift + stagger;
+    lincnt = session.params.lines + max_shift + session.num_staggered_lines;
 
     dev->session = session;
     dev->current_setup.pixels = (session.optical_pixels * session.params.xres) / session.optical_resolution;
@@ -2122,8 +2104,8 @@ dummy \ scanned lines
   dev->current_setup.exposure_time = exposure_time;
     dev->current_setup.xres = session.params.xres;
     dev->current_setup.ccd_size_divisor = session.ccd_size_divisor;
-  dev->current_setup.stagger = stagger;
+    dev->current_setup.stagger = session.num_staggered_lines;
-  dev->current_setup.max_shift = max_shift + stagger;
+    dev->current_setup.max_shift = max_shift + session.num_staggered_lines;
 }
 
 // for fast power saving methods only, like disabling certain amplifiers

backend/genesys_gl843.cc

@@ -1197,14 +1197,7 @@ static void gl843_compute_session(Genesys_Device* dev, ScanSession& s,
     // to retrieve from the chip
     s.output_pixels = (s.optical_pixels * s.output_resolution) / s.optical_resolution;
 
-    // Note: staggering is not applied for calibration. Staggering starts at 2400 dpi
+
-    s.num_staggered_lines = 0;
-    if ((s.params.yres > 1200) &&
-        ((s.params.flags & SCAN_FLAG_IGNORE_LINE_DISTANCE) == 0) &&
-        (dev->model->flags & GENESYS_FLAG_STAGGERED_LINE))
-    {
-        s.num_staggered_lines = (4 * s.params.yres) / dev->motor.base_ydpi;
-    }
 
     s.max_color_shift_lines = sanei_genesys_compute_max_shift(dev, s.params.channels,
                                                               s.params.yres, s.params.flags);
@@ -1383,7 +1376,6 @@ gl843_calculate_current_setup(Genesys_Device * dev, const Genesys_Sensor& sensor
 
   unsigned int lincnt;
   int exposure;
-  int stagger;
 
   int max_shift;
 
@@ -1428,14 +1420,6 @@ gl843_calculate_current_setup(Genesys_Device * dev, const Genesys_Sensor& sensor
 
     gl843_compute_session(dev, session, sensor);
 
-  /* stagger */
-    if (session.ccd_size_divisor == 1 && (dev->model->flags & GENESYS_FLAG_STAGGERED_LINE)) {
-        stagger = (4 * session.params.yres) / dev->motor.base_ydpi;
-    } else {
-        stagger = 0;
-    }
-  DBG(DBG_info, "%s: stagger=%d lines\n", __func__, stagger);
-
   /* compute scan parameters values */
   /* pixels are allways given at half or full CCD optical resolution */
   /* use detected left margin  and fixed value */
@@ -1463,7 +1447,7 @@ gl843_calculate_current_setup(Genesys_Device * dev, const Genesys_Sensor& sensor
                                                 session.params.yres, 0);
 
   /* lincnt */
-    lincnt = session.params.lines + max_shift + stagger;
+    lincnt = session.params.lines + max_shift + session.num_staggered_lines;
 
     dev->session = session;
     dev->current_setup.pixels = (session.optical_pixels * session.params.xres) / session.optical_resolution;
@@ -1472,8 +1456,8 @@ gl843_calculate_current_setup(Genesys_Device * dev, const Genesys_Sensor& sensor
   dev->current_setup.exposure_time = exposure;
     dev->current_setup.xres = session.params.xres;
   dev->current_setup.ccd_size_divisor = session.ccd_size_divisor;
-  dev->current_setup.stagger = stagger;
+    dev->current_setup.stagger = session.num_staggered_lines;
-  dev->current_setup.max_shift = max_shift + stagger;
+    dev->current_setup.max_shift = max_shift + session.num_staggered_lines;
 
   DBG(DBG_proc, "%s: completed\n", __func__);
 }

backend/genesys_gl846.cc

@@ -956,7 +956,6 @@ static void gl846_init_scan_regs(Genesys_Device* dev, const Genesys_Sensor& sens
   unsigned int lincnt;
   unsigned int mflags; /**> motor flags */
   int exposure_time;
-  int stagger;
 
   int slope_dpi = 0;
   int dummy = 0;
@@ -964,14 +963,6 @@ static void gl846_init_scan_regs(Genesys_Device* dev, const Genesys_Sensor& sens
   int max_shift;
   size_t requested_buffer_size, read_buffer_size;
 
-  /* stagger */
-    if (session.ccd_size_divisor == 1 && (dev->model->flags & GENESYS_FLAG_STAGGERED_LINE)) {
-        stagger = (4 * session.params.yres) / dev->motor.base_ydpi;
-    } else {
-        stagger = 0;
-    }
-  DBG(DBG_info, "%s : stagger=%d lines\n", __func__, stagger);
-
   /* compute scan parameters values */
   /* pixels are allways given at full optical resolution */
   /* use detected left margin and fixed value */
@@ -979,7 +970,7 @@ static void gl846_init_scan_regs(Genesys_Device* dev, const Genesys_Sensor& sens
   /* add x coordinates */
     start = session.params.startx;
 
-    if (stagger > 0) {
+    if (session.num_staggered_lines > 0) {
         start |= 1;
     }
 
@@ -1022,8 +1013,7 @@ static void gl846_init_scan_regs(Genesys_Device* dev, const Genesys_Sensor& sens
   max_shift = sanei_genesys_compute_max_shift(dev, session.params.channels, session.params.yres,
                                               session.params.flags);
 
-  /* lincnt */
+    lincnt = session.params.lines + max_shift + session.num_staggered_lines;
-  lincnt = session.params.lines + max_shift + stagger;
 
   /* add tl_y to base movement */
   move = session.params.starty;
@@ -1050,7 +1040,7 @@ static void gl846_init_scan_regs(Genesys_Device* dev, const Genesys_Sensor& sens
   requested_buffer_size = 8 * bytes_per_line;
 
     read_buffer_size = 2 * requested_buffer_size +
-            ((max_shift + stagger) * session.optical_pixels * session.params.channels *
+            ((max_shift + session.num_staggered_lines) * session.optical_pixels * session.params.channels *
              session.params.depth) / 8;
 
     dev->read_buffer.clear();
@@ -1076,8 +1066,8 @@ static void gl846_init_scan_regs(Genesys_Device* dev, const Genesys_Sensor& sens
   dev->current_setup.exposure_time = exposure_time;
     dev->current_setup.xres = session.params.xres;
     dev->current_setup.ccd_size_divisor = session.ccd_size_divisor;
-  dev->current_setup.stagger = stagger;
+    dev->current_setup.stagger = session.num_staggered_lines;
-  dev->current_setup.max_shift = max_shift + stagger;
+    dev->current_setup.max_shift = max_shift + session.num_staggered_lines;
 
 /* TODO: should this be done elsewhere? */
   /* scan bytes to send to the frontend */
@@ -1114,7 +1104,6 @@ gl846_calculate_current_setup(Genesys_Device * dev, const Genesys_Sensor& sensor
 
   unsigned int lincnt;
   int exposure_time;
-  int stagger;
 
   int slope_dpi;
   int dummy = 0;
@@ -1145,13 +1134,6 @@ gl846_calculate_current_setup(Genesys_Device * dev, const Genesys_Sensor& sensor
 
     gl846_compute_session(dev, session, sensor);
 
-    if (dev->model->flags & GENESYS_FLAG_STAGGERED_LINE) {
-        stagger = (4 * session.params.yres) / dev->motor.base_ydpi;
-    } else {
-        stagger = 0;
-    }
-  DBG(DBG_info, "%s: stagger=%d lines\n", __func__, stagger);
-
   /* compute scan parameters values */
   /* pixels are allways given at half or full CCD optical resolution */
   /* use detected left margin  and fixed value */
@@ -1174,7 +1156,7 @@ gl846_calculate_current_setup(Genesys_Device * dev, const Genesys_Sensor& sensor
 
     max_shift = sanei_genesys_compute_max_shift(dev, session.params.channels, session.params.yres, 0);
 
-    lincnt = session.params.lines + max_shift + stagger;
+    lincnt = session.params.lines + max_shift + session.num_staggered_lines;
 
     dev->session = session;
     dev->current_setup.pixels = (session.optical_pixels * session.params.xres) / sensor.optical_res;
@@ -1182,8 +1164,8 @@ gl846_calculate_current_setup(Genesys_Device * dev, const Genesys_Sensor& sensor
   dev->current_setup.exposure_time = exposure_time;
     dev->current_setup.xres = session.params.xres;
     dev->current_setup.ccd_size_divisor = session.ccd_size_divisor;
-  dev->current_setup.stagger = stagger;
+    dev->current_setup.stagger = session.num_staggered_lines;
-  dev->current_setup.max_shift = max_shift + stagger;
+    dev->current_setup.max_shift = max_shift + session.num_staggered_lines;
 }
 
 // for fast power saving methods only, like disabling certain amplifiers

backend/genesys_gl847.cc

@@ -975,7 +975,6 @@ static void gl847_init_scan_regs(Genesys_Device* dev, const Genesys_Sensor& sens
   unsigned int lincnt;
   unsigned int mflags; /**> motor flags */
   int exposure_time;
-  int stagger;
 
   int slope_dpi = 0;
   int dummy = 0;
@@ -983,14 +982,6 @@ static void gl847_init_scan_regs(Genesys_Device* dev, const Genesys_Sensor& sens
   int max_shift;
   size_t requested_buffer_size, read_buffer_size;
 
-  /* stagger */
-    if (session.ccd_size_divisor == 1 && (dev->model->flags & GENESYS_FLAG_STAGGERED_LINE)) {
-        stagger = (4 * session.params.yres) / dev->motor.base_ydpi;
-    } else {
-        stagger = 0;
-    }
-  DBG(DBG_info, "%s : stagger=%d lines\n", __func__, stagger);
-
   /* compute scan parameters values */
   /* pixels are allways given at full optical resolution */
   /* use detected left margin and fixed value */
@@ -998,7 +989,7 @@ static void gl847_init_scan_regs(Genesys_Device* dev, const Genesys_Sensor& sens
   /* add x coordinates */
     start = session.params.startx;
 
-    if (stagger > 0) {
+    if (session.num_staggered_lines > 0) {
         start |= 1;
     }
 
@@ -1041,7 +1032,7 @@ static void gl847_init_scan_regs(Genesys_Device* dev, const Genesys_Sensor& sens
     max_shift = sanei_genesys_compute_max_shift(dev, session.params.channels, session.params.yres,
                                                 session.params.flags);
 
-    lincnt = session.params.lines + max_shift + stagger;
+    lincnt = session.params.lines + max_shift + session.num_staggered_lines;
 
     move = session.params.starty;
     DBG(DBG_info, "%s: move=%d steps\n", __func__, move);
@@ -1067,8 +1058,8 @@ static void gl847_init_scan_regs(Genesys_Device* dev, const Genesys_Sensor& sens
   requested_buffer_size = 8 * bytes_per_line;
 
     read_buffer_size = 2 * requested_buffer_size +
-            ((max_shift + stagger) * session.optical_pixels * session.params.channels *
+            ((max_shift + session.num_staggered_lines) * session.optical_pixels *
-             session.params.depth) / 8;
+             session.params.channels * session.params.depth) / 8;
 
     dev->read_buffer.clear();
     dev->read_buffer.alloc(read_buffer_size);
@@ -1093,8 +1084,8 @@ static void gl847_init_scan_regs(Genesys_Device* dev, const Genesys_Sensor& sens
   dev->current_setup.exposure_time = exposure_time;
     dev->current_setup.xres = session.params.xres;
   dev->current_setup.ccd_size_divisor = session.ccd_size_divisor;
-  dev->current_setup.stagger = stagger;
+    dev->current_setup.stagger = session.num_staggered_lines;
-  dev->current_setup.max_shift = max_shift + stagger;
+    dev->current_setup.max_shift = max_shift + session.num_staggered_lines;
 
 /* TODO: should this be done elsewhere? */
   /* scan bytes to send to the frontend */
@@ -1130,7 +1121,6 @@ gl847_calculate_current_setup(Genesys_Device * dev, const Genesys_Sensor& sensor
 
   unsigned int lincnt;
   int exposure_time;
-  int stagger;
 
   int slope_dpi = 0;
   int dummy = 0;
@@ -1166,15 +1156,6 @@ gl847_calculate_current_setup(Genesys_Device * dev, const Genesys_Sensor& sensor
   /* optical_res */
   optical_res = sensor.optical_res;
 
-  /* stagger */
-    if (dev->model->flags & GENESYS_FLAG_STAGGERED_LINE) {
-        stagger = (4 * session.params.yres) / dev->motor.base_ydpi;
-    } else {
-        stagger = 0;
-    }
-
-  DBG(DBG_info, "%s: stagger=%d lines\n", __func__, stagger);
-
   /* compute scan parameters values */
   /* pixels are allways given at half or full CCD optical resolution */
   /* use detected left margin  and fixed value */
@@ -1198,7 +1179,7 @@ gl847_calculate_current_setup(Genesys_Device * dev, const Genesys_Sensor& sensor
 
     max_shift = sanei_genesys_compute_max_shift(dev, session.params.channels, session.params.yres, 0);
 
-    lincnt = session.params.lines + max_shift + stagger;
+    lincnt = session.params.lines + max_shift + session.num_staggered_lines;
 
     dev->session = session;
     dev->current_setup.pixels = (session.optical_pixels * session.params.xres) / optical_res;
@@ -1206,8 +1187,8 @@ gl847_calculate_current_setup(Genesys_Device * dev, const Genesys_Sensor& sensor
   dev->current_setup.exposure_time = exposure_time;
     dev->current_setup.xres = session.params.xres;
     dev->current_setup.ccd_size_divisor = session.ccd_size_divisor;
-  dev->current_setup.stagger = stagger;
+    dev->current_setup.stagger = session.num_staggered_lines;
-  dev->current_setup.max_shift = max_shift + stagger;
+    dev->current_setup.max_shift = max_shift + session.num_staggered_lines;
 }
 
 // for fast power saving methods only, like disabling certain amplifiers

backend/genesys_low.cc

@@ -1179,6 +1179,45 @@ void compute_session(Genesys_Device* dev, ScanSession& s, const Genesys_Sensor&
         // In quarter-CCD mode optical_pixels is 4x larger than the actual physical number
         s.optical_pixels = align_int_up(s.optical_pixels, 2 * s.ccd_size_divisor);
     }
+
+    // TODO output_pixels
+
+    // Note: staggering is not applied for calibration. Staggering starts at 2400 dpi
+    s.num_staggered_lines = 0;
+
+    if (dev->model->asic_type == AsicType::GL124 ||
+        dev->model->asic_type == AsicType::GL841 ||
+        dev->model->asic_type == AsicType::GL845 ||
+        dev->model->asic_type == AsicType::GL846 ||
+        dev->model->asic_type == AsicType::GL847)
+    {
+        if (s.ccd_size_divisor == 1 && (dev->model->flags & GENESYS_FLAG_STAGGERED_LINE)) {
+            s.num_staggered_lines = (4 * s.params.yres) / dev->motor.base_ydpi;
+        }
+    }
+
+    if (dev->model->asic_type == AsicType::GL646) {
+        if (s.ccd_size_divisor == 1 && (dev->model->flags & GENESYS_FLAG_STAGGERED_LINE)) {
+            // for HP3670, stagger happens only at >=1200 dpi
+            if ((dev->model->motor_type != MOTOR_HP3670 &&
+                 dev->model->motor_type != MOTOR_HP2400) ||
+                s.params.yres >= (unsigned) sensor.optical_res)
+            {
+                s.num_staggered_lines = (4 * s.params.yres) / dev->motor.base_ydpi;
+            }
+        }
+    }
+
+
+    if (dev->model->asic_type == AsicType::GL843) {
+        if ((s.params.yres > 1200) && // FIXME: maybe ccd_size_divisor is the one that controls this?
+            ((s.params.flags & SCAN_FLAG_IGNORE_LINE_DISTANCE) == 0) &&
+            (dev->model->flags & GENESYS_FLAG_STAGGERED_LINE))
+        {
+            s.num_staggered_lines = (4 * s.params.yres) / dev->motor.base_ydpi;
+        }
+    }
+
 }
 
 /** @brief initialize device

backend/genesys_settings.h

@@ -252,7 +252,6 @@ struct ScanSession {
     unsigned output_line_count = 0;
 
     // the number of staggered lines (i.e. lines that overlap during scanning due to line being
-    // gl843-only
     // thinner than the CCD element)
     unsigned num_staggered_lines = 0;