When the scsi request queue is initialized/allocated, the scsi driver clamps hw_max_sectors against the dma max mapping size of sdev->host->dma_dev. The clamping is apparently inappriorate to USB drives.
Either way we are calling blk_queue_max_hw_sectors() in the usb drivers for some (but not all) cases, which causes the clamping to be overriden (inconsistently) anyway.
Therefore the usb driver should always set hw_max_sectors and do the clamping against the right device itself.
Signed-off-by: Tom Yan <tom.ty89@xxxxxxxxx>
---
drivers/usb/storage/scsiglue.c | 37 ++++++++++++++++------------------
drivers/usb/storage/uas.c | 23 ++++++++++++++++-----
2 files changed, 35 insertions(+), 25 deletions(-)
diff --git a/drivers/usb/storage/scsiglue.c b/drivers/usb/storage/scsiglue.c
index e5a971b83e3f..804cbc0ba4da 100644
--- a/drivers/usb/storage/scsiglue.c
+++ b/drivers/usb/storage/scsiglue.c
@@ -120,6 +120,23 @@ static int slave_configure(struct scsi_device *sdev)
* better throughput on most devices.
*/
blk_queue_max_hw_sectors(sdev->request_queue, 2048);
+ } else {
+ /*
+ * Some devices are known to choke with anything larger. It seems like
+ * the problem stems from the fact that original IDE controllers had
+ * only an 8-bit register to hold the number of sectors in one transfer
+ * and even those couldn't handle a full 256 sectors.
+ *
+ * Because we want to make sure we interoperate with as many devices as
+ * possible, we will maintain a 240 sector transfer size limit for USB
+ * Mass Storage devices.
+ *
+ * Tests show that other operating have similar limits with Microsoft
+ * Windows 7 limiting transfers to 128 sectors for both USB2 and USB3
+ * and Apple Mac OS X 10.11 limiting transfers to 256 sectors for USB2
+ * and 2048 for USB3 devices.
+ */
+ blk_queue_max_hw_sectors(sdev->request_queue, 240);
}
/*
@@ -626,26 +643,6 @@ static const struct scsi_host_template usb_stor_host_template = {
/* lots of sg segments can be handled */
.sg_tablesize = SG_MAX_SEGMENTS,
-
- /*
- * Limit the total size of a transfer to 120 KB.
- *
- * Some devices are known to choke with anything larger. It seems like
- * the problem stems from the fact that original IDE controllers had
- * only an 8-bit register to hold the number of sectors in one transfer
- * and even those couldn't handle a full 256 sectors.
- *
- * Because we want to make sure we interoperate with as many devices as
- * possible, we will maintain a 240 sector transfer size limit for USB
- * Mass Storage devices.
- *
- * Tests show that other operating have similar limits with Microsoft
- * Windows 7 limiting transfers to 128 sectors for both USB2 and USB3
- * and Apple Mac OS X 10.11 limiting transfers to 256 sectors for USB2
- * and 2048 for USB3 devices.
- */
- .max_sectors = 240,
-
/* emulated HBA */
.emulated = 1,
diff --git a/drivers/usb/storage/uas.c b/drivers/usb/storage/uas.c
index 08f9296431e9..cffa435afd84 100644
--- a/drivers/usb/storage/uas.c
+++ b/drivers/usb/storage/uas.c
@@ -827,11 +827,6 @@ static int uas_slave_alloc(struct scsi_device *sdev)
*/
blk_queue_update_dma_alignment(sdev->request_queue, (512 - 1));
- if (devinfo->flags & US_FL_MAX_SECTORS_64)
- blk_queue_max_hw_sectors(sdev->request_queue, 64);
- else if (devinfo->flags & US_FL_MAX_SECTORS_240)
- blk_queue_max_hw_sectors(sdev->request_queue, 240);
-
return 0;
}
@@ -839,6 +834,24 @@ static int uas_slave_configure(struct scsi_device *sdev)
{
struct uas_dev_info *devinfo = sdev->hostdata;
+ struct us_data *us = host_to_us(sdev->host);
+ struct device *dev = us->pusb_dev->bus->sysdev;
+
+ if (devinfo->flags & US_FL_MAX_SECTORS_64)
+ blk_queue_max_hw_sectors(sdev->request_queue, 64);
+ else if (devinfo->flags & US_FL_MAX_SECTORS_240)
+ blk_queue_max_hw_sectors(sdev->request_queue, 240);
+ else
+ blk_queue_max_hw_sectors(sdev->request_queue, SCSI_DEFAULT_MAX_SECTORS);
+
+ /*
+ * The max_hw_sectors should be up to maximum size of a mapping for
+ * the device. Otherwise, a DMA API might fail on swiotlb environment.
+ */
+ blk_queue_max_hw_sectors(sdev->request_queue,
+ min_t(size_t, queue_max_hw_sectors(sdev->request_queue),
+ dma_max_mapping_size(dev) >> SECTOR_SHIFT));
+
if (devinfo->flags & US_FL_NO_REPORT_OPCODES)
sdev->no_report_opcodes = 1;
--
2.28.0
