libata: fix ATAPI DMA alignment issues
ATAPI needs to be padded to next 4 byte boundary, if misaligned.
Original work by me, many fixes from Tejun Heo.
diff --git a/include/linux/libata.h b/include/linux/libata.h
index ceee1fc..3ab6762 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -154,6 +154,10 @@
ATA_SHIFT_UDMA = 0,
ATA_SHIFT_MWDMA = 8,
ATA_SHIFT_PIO = 11,
+
+ /* size of buffer to pad xfers ending on unaligned boundaries */
+ ATA_DMA_PAD_SZ = 4,
+ ATA_DMA_PAD_BUF_SZ = ATA_DMA_PAD_SZ * ATA_MAX_QUEUE,
};
enum pio_task_states {
@@ -237,9 +241,12 @@
unsigned long flags; /* ATA_QCFLAG_xxx */
unsigned int tag;
unsigned int n_elem;
+ unsigned int orig_n_elem;
int dma_dir;
+ unsigned int pad_len;
+
unsigned int nsect;
unsigned int cursect;
@@ -250,9 +257,11 @@
unsigned int cursg_ofs;
struct scatterlist sgent;
+ struct scatterlist pad_sgent;
void *buf_virt;
- struct scatterlist *sg;
+ /* DO NOT iterate over __sg manually, use ata_for_each_sg() */
+ struct scatterlist *__sg;
ata_qc_cb_t complete_fn;
@@ -295,6 +304,9 @@
struct ata_prd *prd; /* our SG list */
dma_addr_t prd_dma; /* and its DMA mapping */
+ void *pad; /* array of DMA pad buffers */
+ dma_addr_t pad_dma;
+
struct ata_ioports ioaddr; /* ATA cmd/ctl/dma register blocks */
u8 ctl; /* cache of ATA control register */
@@ -458,6 +470,19 @@
#endif /* CONFIG_PCI */
+static inline struct scatterlist *
+ata_qc_next_sg(struct scatterlist *sg, struct ata_queued_cmd *qc)
+{
+ if (sg == &qc->pad_sgent)
+ return NULL;
+ if (++sg - qc->__sg < qc->n_elem)
+ return sg;
+ return qc->pad_len ? &qc->pad_sgent : NULL;
+}
+
+#define ata_for_each_sg(sg, qc) \
+ for (sg = qc->__sg; sg; sg = ata_qc_next_sg(sg, qc))
+
static inline unsigned int ata_tag_valid(unsigned int tag)
{
return (tag < ATA_MAX_QUEUE) ? 1 : 0;