usb-storage: Fix devices that cannot handle 32k transfers
When a device cannot handle the smallest previously limited transfer
size (64 blocks) without stalling, limit the device to the amount of
packets that fit in a platform native page.
The lowest possible limit is PAGE_CACHE_SIZE, so if the device is ever
used on a platform that has larger than 8K pages, you lose unless you
can convince the device firmware folks to fix the issue.
Cc: Mathew Dharm <mdharm-scsi@one-eyed-alien.net>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Pete Zaitcev <zaitcev@redhat.com>
Signed-off-by: Doug Maxey <dwm@austin.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/usb/storage/scsiglue.c b/drivers/usb/storage/scsiglue.c
index 836a34a..7c9593b 100644
--- a/drivers/usb/storage/scsiglue.c
+++ b/drivers/usb/storage/scsiglue.c
@@ -114,9 +114,15 @@
* while others have trouble with more than 64K. At this time we
* are limiting both to 32K (64 sectores).
*/
- if ((us->flags & US_FL_MAX_SECTORS_64) &&
- sdev->request_queue->max_sectors > 64)
- blk_queue_max_sectors(sdev->request_queue, 64);
+ if (us->flags & (US_FL_MAX_SECTORS_64 | US_FL_MAX_SECTORS_MIN)) {
+ unsigned int max_sectors = 64;
+
+ if (us->flags & US_FL_MAX_SECTORS_MIN)
+ max_sectors = PAGE_CACHE_SIZE >> 9;
+ if (sdev->request_queue->max_sectors > max_sectors)
+ blk_queue_max_sectors(sdev->request_queue,
+ max_sectors);
+ }
/* We can't put these settings in slave_alloc() because that gets
* called before the device type is known. Consequently these