[PATCH/RFC 3/4] CHS: support overriding the ata_rwcmd_protocol() function

[Albert Lee <albertcc@tw.ibm.com>]

Patch 3/4:
  support overriding the ata_rwcmd_protocol() function for some VIA 
adapters per Alan's advice.

For your review, thanks.

Albert
Signed-off-by: Albert Lee <albertcc@tw.ibm.com>

=======

--- ch2/include/linux/libata.h    2005-10-05 18:11:12.000000000 +0800
+++ ch3/include/linux/libata.h    2005-10-05 18:11:51.000000000 +0800
@@ -353,6 +353,8 @@ struct ata_port_operations {
     void (*phy_reset) (struct ata_port *ap);
     void (*post_set_mode) (struct ata_port *ap);
 
+    /* workaround host adapter limitations */
+    void (*rwcmd_protocol) (struct ata_queued_cmd *qc);
     int (*check_atapi_dma) (struct ata_queued_cmd *qc);
 
     void (*bmdma_setup) (struct ata_queued_cmd *qc);
--- ch2/drivers/scsi/libata-core.c    2005-10-05 18:11:12.000000000 +0800
+++ ch3/drivers/scsi/libata-core.c    2005-10-05 18:11:51.000000000 +0800
@@ -677,7 +677,14 @@ static void ata_qc_rwcmd_protocol(struct
  */
 void ata_rwcmd_protocol(struct ata_queued_cmd *qc)
 {
-    ata_qc_rwcmd_protocol(qc);
+    /* give LLD a chance to override
+     * ex. for some VIA adapters, LLD have to use
+     *     PIO commands if LBA48 + DMA is seen.
+     */
+    if (qc->ap->ops->rwcmd_protocol)
+        qc->ap->ops->rwcmd_protocol(qc);
+    else
+        ata_qc_rwcmd_protocol(qc);
 }
 
 static const char * xfer_mode_str[] = {