libata: Don't fail device revalidation for bad _GTF methods

Experience suggests that the _GTF method may be bad. We currently fail
device revalidation in that case, which seems excessive.
Signed-off-by: Matthew Garrett <mjg59@srcf.ucam.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

drivers/ata/libata-acpi.c

@@ -312,7 +312,7 @@ EXPORT_SYMBOL_GPL(ata_acpi_stm);
  *
  * RETURNS:
  * Number of taskfiles on success, 0 if _GTF doesn't exist or doesn't
- * contain valid data.  -errno on other errors.
+ * contain valid data.
  */
 static int ata_dev_get_GTF(struct ata_device *dev, struct ata_acpi_gtf **gtf,
 			   void **ptr_to_free)
@@ -339,7 +339,6 @@ static int ata_dev_get_GTF(struct ata_device *dev, struct ata_acpi_gtf **gtf,
 			ata_dev_printk(dev, KERN_WARNING,
 				       "_GTF evaluation failed (AE 0x%x)\n",
 				       status);
-			rc = -EIO;
 		}
 		goto out_free;
 	}
@@ -359,7 +358,6 @@ static int ata_dev_get_GTF(struct ata_device *dev, struct ata_acpi_gtf **gtf,
 		ata_dev_printk(dev, KERN_WARNING,
 			       "_GTF unexpected object type 0x%x\n",
 			       out_obj->type);
-		rc = -EINVAL;
 		goto out_free;
 	}
 
@@ -367,7 +365,6 @@ static int ata_dev_get_GTF(struct ata_device *dev, struct ata_acpi_gtf **gtf,
 		ata_dev_printk(dev, KERN_WARNING,
 			       "unexpected _GTF length (%d)\n",
 			       out_obj->buffer.length);
-		rc = -EINVAL;
 		goto out_free;
 	}
 
@@ -511,10 +508,7 @@ static int ata_acpi_exec_tfs(struct ata_device *dev)
 	int gtf_count, i, rc;
 
 	/* get taskfiles */
-	rc = ata_dev_get_GTF(dev, &gtf, &ptr_to_free);
-	if (rc < 0)
-		return rc;
-	gtf_count = rc;
+	gtf_count = ata_dev_get_GTF(dev, &gtf, &ptr_to_free);
 
 	/* execute them */
 	for (i = 0, rc = 0; i < gtf_count; i++) {