libata: Fall back to unqueued READ LOG EXT if the DMA variant fails

Some devices advertise support for the READ/WRITE LOG DMA EXT commands
but fail when we try to issue them. This can lead to queued TRIM being
unintentionally disabled since the relevant feature flag is located in a
general purpose log page.

Fall back to unqueued READ LOG EXT if the DMA variant fails while
reading a log page.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Tejun Heo <tj@kernel.org>

drivers/ata/libata-eh.c

@@ -1507,13 +1507,17 @@ unsigned int ata_read_log_page(struct ata_device *dev, u8 log,
 {
 	struct ata_taskfile tf;
 	unsigned int err_mask;
+	bool dma = false;
 
 	DPRINTK("read log page - log 0x%x, page 0x%x\n", log, page);
 
+retry:
 	ata_tf_init(dev, &tf);
-	if (dev->dma_mode && ata_id_has_read_log_dma_ext(dev->id)) {
+	if (dev->dma_mode && ata_id_has_read_log_dma_ext(dev->id) &&
+	    !(dev->horkage & ATA_HORKAGE_NO_NCQ_LOG)) {
 		tf.command = ATA_CMD_READ_LOG_DMA_EXT;
 		tf.protocol = ATA_PROT_DMA;
+		dma = true;
 	} else {
 		tf.command = ATA_CMD_READ_LOG_EXT;
 		tf.protocol = ATA_PROT_PIO;
@@ -1527,6 +1531,12 @@ unsigned int ata_read_log_page(struct ata_device *dev, u8 log,
 	err_mask = ata_exec_internal(dev, &tf, NULL, DMA_FROM_DEVICE,
 				     buf, sectors * ATA_SECT_SIZE, 0);
 
+	if (err_mask && dma) {
+		dev->horkage |= ATA_HORKAGE_NO_NCQ_LOG;
+		ata_dev_warn(dev, "READ LOG DMA EXT failed, trying unqueued\n");
+		goto retry;
+	}
+
 	DPRINTK("EXIT, err_mask=%x\n", err_mask);
 	return err_mask;
 }

include/linux/libata.h

@@ -424,6 +424,7 @@ enum {
 	ATA_HORKAGE_NOLPM	= (1 << 20),	/* don't use LPM */
 	ATA_HORKAGE_WD_BROKEN_LPM = (1 << 21),	/* some WDs have broken LPM */
 	ATA_HORKAGE_ZERO_AFTER_TRIM = (1 << 22),/* guarantees zero after trim */
+	ATA_HORKAGE_NO_NCQ_LOG	= (1 << 23),	/* don't use NCQ for log read */
 
 	 /* DMA mask for user DMA control: User visible values; DO NOT
 	    renumber */