genesys: Extract reliable reading of home sensor to separate function

backend/genesys/gl124.cpp

@@ -1205,18 +1205,7 @@ void CommandSetGl124::slow_back_home(Genesys_Device* dev, bool wait_until_home)
     // post scan gpio : without that HOMSNR is unreliable
     gl124_homsnr_gpio(dev);
 
-    // first read gives HOME_SENSOR true
+    auto status = scanner_read_reliable_status(*dev);
-    auto status = scanner_read_status(*dev);
-    if (DBG_LEVEL >= DBG_io) {
-        debug_print_status(dbg, status);
-    }
-    dev->interface->sleep_ms(100);
-
-    // second is reliable
-    status = scanner_read_status(*dev);
-    if (DBG_LEVEL >= DBG_io) {
-        debug_print_status(dbg, status);
-    }
 
     if (status.is_at_home) {
       DBG (DBG_info, "%s: already at home, completed\n", __func__);

backend/genesys/gl841.cpp

@@ -2257,17 +2257,7 @@ void CommandSetGl841::slow_back_home(Genesys_Device* dev, bool wait_until_home)
     dev->cmd_set->save_power(dev, false);
 
     // first read gives HOME_SENSOR true
-    auto status = scanner_read_status(*dev);
+    auto status = scanner_read_reliable_status(*dev);
-    if (DBG_LEVEL >= DBG_io) {
-        debug_print_status(dbg, status);
-    }
-    dev->interface->sleep_ms(100);
-
-    // second is reliable
-    status = scanner_read_status(*dev);
-    if (DBG_LEVEL >= DBG_io) {
-        debug_print_status(dbg, status);
-    }
 
   dev->scanhead_position_in_steps = 0;
 

backend/genesys/gl843.cpp

@@ -1811,19 +1811,7 @@ void CommandSetGl843::slow_back_home(Genesys_Device* dev, bool wait_until_home)
   /* regular slow back home */
   dev->scanhead_position_in_steps = 0;
 
-    // first read gives HOME_SENSOR true
+    auto status = scanner_read_reliable_status(*dev);
-    auto status = scanner_read_status(*dev);
-    if (DBG_LEVEL >= DBG_io) {
-        debug_print_status(dbg, status);
-    }
-
-    dev->interface->sleep_ms(100);
-
-    // second is reliable
-    status = scanner_read_status(*dev);
-    if (DBG_LEVEL >= DBG_io) {
-        debug_print_status(dbg, status);
-    }
 
     if (status.is_at_home) {
         return;

backend/genesys/gl846.cpp

@@ -957,17 +957,7 @@ void CommandSetGl846::slow_back_home(Genesys_Device* dev, bool wait_until_home)
     gl846_homsnr_gpio(dev);
 
     // first read gives HOME_SENSOR true
-    auto status = scanner_read_status(*dev);
+    auto status = scanner_read_reliable_status(*dev);
-    if (DBG_LEVEL >= DBG_io) {
-        debug_print_status(dbg, status);
-    }
-    dev->interface->sleep_ms(100);
-
-    // second is reliable
-    status = scanner_read_status(*dev);
-    if (DBG_LEVEL >= DBG_io) {
-        debug_print_status(dbg, status);
-    }
 
   /* is sensor at home? */
     if (status.is_at_home) {

backend/genesys/gl847.cpp

@@ -1010,17 +1010,7 @@ void CommandSetGl847::slow_back_home(Genesys_Device* dev, bool wait_until_home)
     gl847_homsnr_gpio(dev);
 
     // first read gives HOME_SENSOR true
-    auto status = scanner_read_status(*dev);
+    auto status = scanner_read_reliable_status(*dev);
-    if (DBG_LEVEL >= DBG_io) {
-        debug_print_status(dbg, status);
-    }
-    dev->interface->sleep_ms(100);
-
-    // second is reliable
-    status = scanner_read_status(*dev);
-    if (DBG_LEVEL >= DBG_io) {
-        debug_print_status(dbg, status);
-    }
 
     if (status.is_at_home) {
       DBG(DBG_info, "%s: already at home, completed\n", __func__);

backend/genesys/low.cpp

@@ -305,6 +305,26 @@ Status scanner_read_status(Genesys_Device& dev)
     return status;
 }
 
+Status scanner_read_reliable_status(Genesys_Device& dev)
+{
+    DBG_HELPER(dbg);
+
+    auto status = scanner_read_status(dev);
+    if (DBG_LEVEL >= DBG_io) {
+        debug_print_status(dbg, status);
+    }
+
+    dev.interface->sleep_ms(100);
+
+    // second is reliable
+    status = scanner_read_status(dev);
+    if (DBG_LEVEL >= DBG_io) {
+        debug_print_status(dbg, status);
+    }
+
+    return status;
+}
+
 /**
  * decodes and prints content of status register
  * @param val value read from status register

backend/genesys/low.h

@@ -250,8 +250,13 @@ inline GenesysRegister* sanei_genesys_get_address(Genesys_Register_Set* regs, ui
 
 extern void sanei_genesys_init_cmd_set(Genesys_Device* dev);
 
+// reads the status of the scanner
 Status scanner_read_status(Genesys_Device& dev);
 
+// reads the status of the scanner reliably. This is done by reading the status twice. The first
+// read sometimes returns the home sensor as engaged when this is not true.
+Status scanner_read_reliable_status(Genesys_Device& dev);
+
 extern void debug_print_status(DebugMessageHelper& dbg, Status status);
 
 extern void sanei_genesys_write_ahb(Genesys_Device* dev, uint32_t addr, uint32_t size,