3 files changed, 83 insertions, 23 deletions

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 48519887f94a..be95fdb69726 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -326,6 +326,44 @@ static void ata_force_horkage(struct ata_device *dev)
 }
 
 /**
+ *      atapi_cmd_type - Determine ATAPI command type from SCSI opcode
+ *      @opcode: SCSI opcode
+ *
+ *      Determine ATAPI command type from @opcode.
+ *
+ *      LOCKING:
+ *      None.
+ *
+ *      RETURNS:
+ *      ATAPI_{READ|WRITE|READ_CD|PASS_THRU|MISC}
+ */
+int atapi_cmd_type(u8 opcode)
+{
+        switch (opcode) {
+        case GPCMD_READ_10:
+        case GPCMD_READ_12:
+                return ATAPI_READ;
+
+        case GPCMD_WRITE_10:
+        case GPCMD_WRITE_12:
+        case GPCMD_WRITE_AND_VERIFY_10:
+                return ATAPI_WRITE;
+
+        case GPCMD_READ_CD:
+        case GPCMD_READ_CD_MSF:
+                return ATAPI_READ_CD;
+
+        case ATA_16:
+        case ATA_12:
+                if (atapi_passthru16)
+                        return ATAPI_PASS_THRU;
+                /* fall thru */
+        default:
+                return ATAPI_MISC;
+        }
+}
+
+/**
  *      ata_tf_to_fis - Convert ATA taskfile to SATA FIS structure
  *      @tf: Taskfile to convert
  *      @pmp: Port multiplier port
@@ -2660,7 +2698,7 @@ int ata_bus_probe(struct ata_port *ap)
            specific sequence bass-ackwards so that PDIAG- is released by
            the slave device */
 
-        ata_link_for_each_dev(dev, &ap->link) {
+        ata_link_for_each_dev_reverse(dev, &ap->link) {
                 if (tries[dev->devno])
                         dev->class = classes[dev->devno];
 
@@ -7774,6 +7812,7 @@ EXPORT_SYMBOL_GPL(ata_tf_read);
 EXPORT_SYMBOL_GPL(ata_noop_dev_select);
 EXPORT_SYMBOL_GPL(ata_std_dev_select);
 EXPORT_SYMBOL_GPL(sata_print_link_status);
+EXPORT_SYMBOL_GPL(atapi_cmd_type);
 EXPORT_SYMBOL_GPL(ata_tf_to_fis);
 EXPORT_SYMBOL_GPL(ata_tf_from_fis);
 EXPORT_SYMBOL_GPL(ata_pack_xfermask);
diff --git a/drivers/ata/pata_ali.c b/drivers/ata/pata_ali.c
index 8786455c901d..ce830fe3a362 100644
--- a/drivers/ata/pata_ali.c
+++ b/drivers/ata/pata_ali.c
@@ -36,6 +36,10 @@
 #define DRV_NAME "pata_ali"
 #define DRV_VERSION "0.7.5"
 
+int ali_atapi_dma = 0;
+module_param_named(atapi_dma, ali_atapi_dma, int, 0644);
+MODULE_PARM_DESC(atapi_dma, "Enable ATAPI DMA (0=disable, 1=enable)");
+
 /*
  *      Cable special cases
  */
@@ -270,6 +274,27 @@ static void ali_set_dmamode(struct ata_port *ap, struct ata_device *adev)
 }
 
 /**
+ *      ali_warn_atapi_dma      -       Warn about ATAPI DMA disablement
+ *      @adev: Device
+ *
+ *      Whine about ATAPI DMA disablement if @adev is an ATAPI device.
+ *      Can be used as ->dev_config.
+ */
+
+static void ali_warn_atapi_dma(struct ata_device *adev)
+{
+        struct ata_eh_context *ehc = &adev->link->eh_context;
+        int print_info = ehc->i.flags & ATA_EHI_PRINTINFO;
+
+        if (print_info && adev->class == ATA_DEV_ATAPI && !ali_atapi_dma) {
+                ata_dev_printk(adev, KERN_WARNING,
+                               "WARNING: ATAPI DMA disabled for reliablity issues.  It can be enabled\n");
+                ata_dev_printk(adev, KERN_WARNING,
+                               "WARNING: via pata_ali.atapi_dma modparam or corresponding sysfs node.\n");
+        }
+}
+
+/**
  *      ali_lock_sectors        -       Keep older devices to 255 sector mode
  *      @adev: Device
  *
@@ -283,6 +308,7 @@ static void ali_set_dmamode(struct ata_port *ap, struct ata_device *adev)
 static void ali_lock_sectors(struct ata_device *adev)
 {
         adev->max_sectors = 255;
+        ali_warn_atapi_dma(adev);
 }
 
 /**
@@ -294,6 +320,18 @@ static void ali_lock_sectors(struct ata_device *adev)
 
 static int ali_check_atapi_dma(struct ata_queued_cmd *qc)
 {
+        if (!ali_atapi_dma) {
+                /* FIXME: pata_ali can't do ATAPI DMA reliably but the
+                 * IDE alim15x3 driver can.  I tried lots of things
+                 * but couldn't find what the actual difference was.
+                 * If you got an idea, please write it to
+                 * linux-ide@vger.kernel.org and cc htejun@gmail.com.
+                 *
+                 * Disable ATAPI DMA for now.
+                 */
+                return -EOPNOTSUPP;
+        }
+
         /* If its not a media command, its not worth it */
         if (atapi_cmd_type(qc->cdb[0]) == ATAPI_MISC)
                 return -EOPNOTSUPP;
@@ -359,6 +397,7 @@ static struct ata_port_operations ali_20_port_ops = {
 
         .tf_load        = ata_tf_load,
         .tf_read        = ata_tf_read,
+        .check_atapi_dma = ali_check_atapi_dma,
         .check_status   = ata_check_status,
         .exec_command   = ata_exec_command,
         .dev_select     = ata_std_dev_select,
@@ -438,6 +477,7 @@ static struct ata_port_operations ali_c5_port_ops = {
         .check_status   = ata_check_status,
         .exec_command   = ata_exec_command,
         .dev_select     = ata_std_dev_select,
+        .dev_config     = ali_warn_atapi_dma,
 
         .freeze         = ata_bmdma_freeze,
         .thaw           = ata_bmdma_thaw,
diff --git a/include/linux/libata.h b/include/linux/libata.h
index b064bfeb69ee..37ee881c42ac 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -350,7 +350,8 @@ enum {
         ATAPI_READ              = 0,            /* READs */
         ATAPI_WRITE             = 1,            /* WRITEs */
         ATAPI_READ_CD           = 2,            /* READ CD [MSF] */
-        ATAPI_MISC              = 3,            /* the rest */
+        ATAPI_PASS_THRU         = 3,            /* SAT pass-thru */
+        ATAPI_MISC              = 4,            /* the rest */
 };
 
 enum ata_xfer_mask {
@@ -849,6 +850,7 @@ extern unsigned int ata_dev_try_classify(struct ata_device *dev, int present,
  */
 extern void ata_tf_load(struct ata_port *ap, const struct ata_taskfile *tf);
 extern void ata_tf_read(struct ata_port *ap, struct ata_taskfile *tf);
+extern int atapi_cmd_type(u8 opcode);
 extern void ata_tf_to_fis(const struct ata_taskfile *tf,
                           u8 pmp, int is_cmd, u8 *fis);
 extern void ata_tf_from_fis(const u8 *fis, struct ata_taskfile *tf);
@@ -1379,27 +1381,6 @@ static inline int ata_try_flush_cache(const struct ata_device *dev)
                ata_id_has_flush_ext(dev->id);
 }
 
-static inline int atapi_cmd_type(u8 opcode)
-{
-        switch (opcode) {
-        case GPCMD_READ_10:
-        case GPCMD_READ_12:
-                return ATAPI_READ;
-
-        case GPCMD_WRITE_10:
-        case GPCMD_WRITE_12:
-        case GPCMD_WRITE_AND_VERIFY_10:
-                return ATAPI_WRITE;
-
-        case GPCMD_READ_CD:
-        case GPCMD_READ_CD_MSF:
-                return ATAPI_READ_CD;
-
-        default:
-                return ATAPI_MISC;
-        }
-}
-
 static inline unsigned int ac_err_mask(u8 status)
 {
         if (status & (ATA_BUSY | ATA_DRQ))