libata: use READ_LOG_DMA_EXT

If READ_LOG_DMA_EXT is supported we should try to use it for
reading the log pages.
Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Tejun Heo <tj@kernel.org>

drivers/ata/libata-eh.c

@@ -1510,13 +1510,18 @@ unsigned int ata_read_log_page(struct ata_device *dev, u8 log,
 	DPRINTK("read log page - log 0x%x, page 0x%x\n", log, page);
 
 	ata_tf_init(dev, &tf);
-	tf.command = ATA_CMD_READ_LOG_EXT;
+	if (dev->dma_mode && ata_id_has_read_log_dma_ext(dev->id)) {
+		tf.command = ATA_CMD_READ_LOG_DMA_EXT;
+		tf.protocol = ATA_PROT_DMA;
+	} else {
+		tf.command = ATA_CMD_READ_LOG_EXT;
+		tf.protocol = ATA_PROT_PIO;
+	}
 	tf.lbal = log;
 	tf.lbam = page;
 	tf.nsect = sectors;
 	tf.hob_nsect = sectors >> 8;
 	tf.flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_LBA48 | ATA_TFLAG_DEVICE;
-	tf.protocol = ATA_PROT_PIO;
 
 	err_mask = ata_exec_internal(dev, &tf, NULL, DMA_FROM_DEVICE,
 				     buf, sectors * ATA_SECT_SIZE, 0);

include/linux/ata.h

@@ -696,6 +696,13 @@ static inline bool ata_id_wcache_enabled(const u16 *id)
 	return id[ATA_ID_CFS_ENABLE_1] & (1 << 5);
 }
 
+static inline bool ata_id_has_read_log_dma_ext(const u16 *id)
+{
+	if (!(id[ATA_ID_CFS_ENABLE_2] & (1 << 15)))
+		return false;
+	return id[ATA_ID_COMMAND_SET_3] & (1 << 3);
+}
+
 /**
  *	ata_id_major_version	-	get ATA level of drive
  *	@id: Identify data