Fix inability to recover from disc errors 08 and 21

Detail:
  These disc errors relate to the status of the task file registers before
  a command is issued, however with SATA (unlike PATA) we can't simply read
  the task file on demand, we need to issue a command to cause a register FIS
  transaction to happen on the bus. The only available command which is
  compatible with all device types (packet and non-packet) and which can be
  issued in not-ready state is EXECUTE_DEVICE_DIAGNOSTIC, so issue this when
  either disc error is encountered and retry to give the drive a chance to
  return to ready/not-busy state. This command has the advantage of having
  been mandatory back to ATA-1 so should be harmless for PATA drives, whether
  connected via a PATA-SATA bridge or via a future PATADriver module.
Admin:
  Tested on Titanium.

Version 4.02. Tagged as 'ADFS-4_02'

VersionNum

-/* (4.01)
+/* (4.02)
  *
  * This file is automatically maintained by srccommit, do not edit manually.
  * Last processed by srccommit version: 1.1.
  *
  */
-#define Module_MajorVersion_CMHG        4.01
+#define Module_MajorVersion_CMHG        4.02
 #define Module_MinorVersion_CMHG        
-#define Module_Date_CMHG                13 Mar 2016
+#define Module_Date_CMHG                24 Mar 2016
 
-#define Module_MajorVersion             "4.01"
-#define Module_Version                  401
+#define Module_MajorVersion             "4.02"
+#define Module_Version                  402
 #define Module_MinorVersion             ""
-#define Module_Date                     "13 Mar 2016"
+#define Module_Date                     "24 Mar 2016"
 
-#define Module_ApplicationDate          "13-Mar-16"
+#define Module_ApplicationDate          "24-Mar-16"
 
 #define Module_ComponentName            "ADFS"
 #define Module_ComponentPath            "cddl/RiscOS/Sources/FileSys/ADFS/ADFS"
 
-#define Module_FullVersion              "4.01"
-#define Module_HelpVersion              "4.01 (13 Mar 2016)"
-#define Module_LibraryVersionInfo       "4:1"
+#define Module_FullVersion              "4.02"
+#define Module_HelpVersion              "4.02 (24 Mar 2016)"
+#define Module_LibraryVersionInfo       "4:2"

c/discop

@@ -169,6 +169,26 @@ static low_level_error_t transfer_with_retries(uint32_t reason,
       e.oserror = MESSAGE_ERRORLOOKUP(true, ExtEscape, 0);
       break; /* No retries for this one */
     }
+    else if (e.oserror && (e.oserror->errnum == ErrorNumber_ATA_CmdBusy ||
+                           e.oserror->errnum == ErrorNumber_ATA_CmdNotRdy))
+    {
+      /* With SATA, we need to kick the device to send us updated task file
+       * registers to enable us to recover from these error conditions. For
+       * this, we need a command with no side effects that is valid to issue
+       * when DRDY is not set; the only candidate valid for all types and
+       * generations of device is EXECUTE_DEVICE_DIAGNOSTIC. Throw away any
+       * errors returned from the kick command. */
+      ataop_param_lba28_t kick_p = {
+          .device = DEVICE_MAGIC,
+          .command = ATACOMMAND_EXECUTE_DEVICE_DIAGNOSTIC
+      };
+      uint32_t kick_flags = ATAOp_NoDRDY |
+          (dr->deviceid << ATAOp_DeviceIDShift) |
+          (dr->cpid << ATAOp_CPIDShift) |
+          ATAOp_TransNone |
+          (flags & ATAOp_DisableEscape);
+      ata_op_fg_nodata(kick_flags, 7, &kick_p, OP_TIMEOUT);
+    }
     if (e.oserror && transferred)
       ++retries; /* At least some data transferred, so it's not fair to decrement the retry count when we loop */
   }

h/globals

@@ -131,6 +131,7 @@ enum
   ATACOMMAND_WRITE_DMA_EXT           = 0x35,
   ATACOMMAND_READ_VERIFY_SECTORS     = 0x40,
   ATACOMMAND_READ_VERIFY_SECTORS_EXT = 0x42,
+  ATACOMMAND_EXECUTE_DEVICE_DIAGNOSTIC = 0x90,
   ATACOMMAND_PACKET                  = 0xA0,
   ATACOMMAND_IDENTIFY_PACKET_DEVICE  = 0xA1,
   ATACOMMAND_READ_DMA                = 0xC8,