From 61bf54b71d5abf767ee46284be19965d7253ddbf Mon Sep 17 00:00:00 2001 From: Oliver Neukum Date: Thu, 8 Feb 2007 09:04:48 +0100 Subject: USB Storage: indistinguishable devices with broken and unbroken firmware there's a USB mass storage device which exists in two version. One reports the correct size and the other does not. Apart from that they are identical and cannot be told apart. Here's a heuristic based on the empirical finding that drives have even sizes. Signed-off-by: Oliver Neukum Acked-by: Alan Stern Acked-by: Matthew Dharm Signed-off-by: Greg Kroah-Hartman --- drivers/scsi/sd.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) (limited to 'drivers/scsi/sd.c') diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c index 3f048bd6326..5a8f55fea5f 100644 --- a/drivers/scsi/sd.c +++ b/drivers/scsi/sd.c @@ -1269,9 +1269,18 @@ repeat: /* Some devices return the total number of sectors, not the * highest sector number. Make the necessary adjustment. */ - if (sdp->fix_capacity) + if (sdp->fix_capacity) { --sdkp->capacity; + /* Some devices have version which report the correct sizes + * and others which do not. We guess size according to a heuristic + * and err on the side of lowering the capacity. */ + } else { + if (sdp->guess_capacity) + if (sdkp->capacity & 0x01) /* odd sizes are odd */ + --sdkp->capacity; + } + got_data: if (sector_size == 0) { sector_size = 512; -- cgit v1.2.3