John Garry [off-list ref] writes:

quoted

diff --git a/drivers/ata/pata_macio.c b/drivers/ata/pata_macio.c
index 817838e2f70e..3cb455a32d92 100644
--- a/drivers/ata/pata_macio.c
+++ b/drivers/ata/pata_macio.c

@@ -915,10 +915,13 @@ static const struct scsi_host_template pata_macio_sht = {
  	.sg_tablesize		= MAX_DCMDS,
  	/* We may not need that strict one */
  	.dma_boundary		= ATA_DMA_BOUNDARY,
-	/* Not sure what the real max is but we know it's less than 64K, let's
-	 * use 64K minus 256
+	/*
+	 * The SCSI core requires the segment size to cover at least a page, so
+	 * for 64K page size kernels this must be at least 64K. However the
+	 * hardware can't handle 64K, so pata_macio_qc_prep() will split large
+	 * requests.
  	 */
-	.max_segment_size	= MAX_DBDMA_SEG,
+	.max_segment_size	= SZ_64K,
  	.device_configure	= pata_macio_device_configure,
  	.sdev_groups		= ata_common_sdev_groups,
  	.can_queue		= ATA_DEF_QUEUE,

Feel free to add:
Reviewed-by: John Garry <john.g.garry@oracle.com>

Thanks.

Sorry I missed adding this when sending the proper patch, maybe whoever
applies it can add it then.

cheers