libata: handle early device PIO modes correctly
diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index 175d464..09639e7 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -1082,6 +1082,31 @@
dev->id[93]);
}
+/*
+ * Compute the PIO modes available for this device. This is not as
+ * trivial as it seems if we must consider early devices correctly.
+ *
+ * FIXME: pre IDE drive timing (do we care ?).
+ */
+
+static unsigned int ata_pio_modes(struct ata_device *adev)
+{
+ u16 modes;
+
+ /* Usual case. Word 53 indicates word 88 is valid */
+ if (adev->id[ATA_ID_FIELD_VALID] & (1 << 2)) {
+ modes = adev->id[ATA_ID_PIO_MODES] & 0x03;
+ modes <<= 3;
+ modes |= 0x7;
+ return modes;
+ }
+
+ /* If word 88 isn't valid then Word 51 holds the PIO timing number
+ for the maximum. Turn it into a mask and return it */
+ modes = (2 << (adev->id[ATA_ID_OLD_PIO_MODES] & 0xFF)) - 1 ;
+ return modes;
+}
+
/**
* ata_dev_identify - obtain IDENTIFY x DEVICE page
* @ap: port on which device we wish to probe resides
@@ -1215,10 +1240,8 @@
xfer_modes = dev->id[ATA_ID_UDMA_MODES];
if (!xfer_modes)
xfer_modes = (dev->id[ATA_ID_MWDMA_MODES]) << ATA_SHIFT_MWDMA;
- if (!xfer_modes) {
- xfer_modes = (dev->id[ATA_ID_PIO_MODES]) << (ATA_SHIFT_PIO + 3);
- xfer_modes |= (0x7 << ATA_SHIFT_PIO);
- }
+ if (!xfer_modes)
+ xfer_modes = ata_pio_modes(dev);
ata_dump_id(dev);