diff options
Diffstat (limited to 'drivers/usb/storage/uas.c')
| -rw-r--r-- | drivers/usb/storage/uas.c | 27 |
1 files changed, 13 insertions, 14 deletions
diff --git a/drivers/usb/storage/uas.c b/drivers/usb/storage/uas.c index 24de9c00d8e2..8391a88cf90f 100644 --- a/drivers/usb/storage/uas.c +++ b/drivers/usb/storage/uas.c @@ -800,20 +800,9 @@ static int uas_slave_alloc(struct scsi_device *sdev) sdev->hostdata = devinfo; /* - * USB has unusual DMA-alignment requirements: Although the - * starting address of each scatter-gather element doesn't matter, - * the length of each element except the last must be divisible - * by the Bulk maxpacket value. There's currently no way to - * express this by block-layer constraints, so we'll cop out - * and simply require addresses to be aligned at 512-byte - * boundaries. This is okay since most block I/O involves - * hardware sectors that are multiples of 512 bytes in length, - * and since host controllers up through USB 2.0 have maxpacket - * values no larger than 512. - * - * But it doesn't suffice for Wireless USB, where Bulk maxpacket - * values can be as large as 2048. To make that work properly - * will require changes to the block layer. + * The protocol has no requirements on alignment in the strict sense. + * Controllers may or may not have alignment restrictions. + * As this is not exported, we use an extremely conservative guess. */ blk_queue_update_dma_alignment(sdev->request_queue, (512 - 1)); @@ -843,6 +832,10 @@ static int uas_slave_configure(struct scsi_device *sdev) sdev->wce_default_on = 1; } + /* Some disks cannot handle READ_CAPACITY_16 */ + if (devinfo->flags & US_FL_NO_READ_CAPACITY_16) + sdev->no_read_capacity_16 = 1; + /* * Some disks return the total number of blocks in response * to READ CAPACITY rather than the highest block number. @@ -852,6 +845,12 @@ static int uas_slave_configure(struct scsi_device *sdev) sdev->fix_capacity = 1; /* + * in some cases we have to guess + */ + if (devinfo->flags & US_FL_CAPACITY_HEURISTICS) + sdev->guess_capacity = 1; + + /* * Some devices don't like MODE SENSE with page=0x3f, * which is the command used for checking if a device * is write-protected. Now that we tell the sd driver |