> > I have a USB bridge that's implementing SAT passthru cdbs. We ran into an
> > issue with the usb-storage driver in that when it does auto-sense (because
> > the CK_COND bit is set in the passthru cdb), the driver does a sense with
> > only 18 bytes for the sense buffer. The problem is that SAT passthru wants
> > to return 22 bytes of sense data. The last 4 bytes that don't get returned
> > are fairly important ATA task files registers: lba high hob, lba high,
> > device, and status.
> >
> > For testing purposes I use the patch below, but what's the correct way to
> > deal with this issue? Is there something in the USB spec mandating 18 bytes
> > of sense data, or is the usb-storage simply making a hard-coded assumption?
>
> I believe it's a hard-coded assumption, based on the observation that many
> USB devices don't like it if you ask for more or less than 18 bytes. Matt
> Dharm can correct this if I'm wrong.
>
> The sense buffer length is yet another quantity that ought to have an SG
> passthru but doesn't.
>
> Your patch looks to me like a reasonable approach, given the constraints
> we are under. It would be nice to have a cleaner way of determining which
> commands need the extra sense data. Could you make that test into a
> separate subroutine? And perhaps use symbolic names for the command
> bytes.
>
> Alan Stern
>
Here is a patch that makes the test a separate routine and uses the
ATA_12/16 opcode defines found in scsi.h. Thoughts?
Thanks,
Tim Thelin
---
diff --git a/drivers/usb/storage/transport.c b/drivers/usb/storage/transport.c
index 7ca896a..cd0ab66 100644
--- a/drivers/usb/storage/transport.c
+++ b/drivers/usb/storage/transport.c
@@ -521,6 +521,14 @@ int usb_stor_bulk_transfer_sg(struct us_
* Transport routines
***********************************************************************/
+static inline u8 usb_stor_sense_data_len(struct scsi_cmnd *srb, struct us_data
*us)
+{
+ if ((us->subclass == US_SC_RBC || us->subclass == US_SC_SCSI) &&
+ (srb->cmnd[0] == ATA_12 || srb->cmnd[0] == ATA_16))
+ return 22;
+ return 18;
+}
+
/* Invoke the transport and basic error-handling/recovery methods
*
* This is used by the protocol layers to actually send the message to
@@ -611,9 +619,13 @@ void usb_stor_invoke_transport(struct sc
unsigned char old_cmd_len;
unsigned char old_cmnd[MAX_COMMAND_SIZE];
int old_resid;
+ u8 sense_data_len;
US_DEBUGP("Issuing auto-REQUEST_SENSE\n");
+ /* get the length before the srb is changed */
+ sense_data_len = usb_stor_sense_data_len(srb, us);
+
/* save the old command */
memcpy(old_cmnd, srb->cmnd, MAX_COMMAND_SIZE);
old_cmd_len = srb->cmd_len;
@@ -622,7 +634,7 @@ void usb_stor_invoke_transport(struct sc
memset(srb->cmnd, 0, MAX_COMMAND_SIZE);
srb->cmnd[0] = REQUEST_SENSE;
srb->cmnd[1] = old_cmnd[1] & 0xE0;
- srb->cmnd[4] = 18;
+ srb->cmnd[4] = sense_data_len;
/* FIXME: we must do the protocol translation here */
if (us->subclass == US_SC_RBC || us->subclass == US_SC_SCSI)
@@ -640,7 +652,7 @@ void usb_stor_invoke_transport(struct sc
/* set the buffer length for transfer */
old_request_bufflen = srb->request_bufflen;
- srb->request_bufflen = US_SENSE_SIZE;
+ srb->request_bufflen = sense_data_len;
/* set up for no scatter-gather use */
old_sg = srb->use_sg;
diff --git a/drivers/usb/storage/usb.h b/drivers/usb/storage/usb.h
index 98b0971..80e3a22 100644
--- a/drivers/usb/storage/usb.h
+++ b/drivers/usb/storage/usb.h
@@ -117,7 +117,7 @@ enum { US_DO_ALL_FLAGS };
*/
#define US_IOBUF_SIZE 64 /* Size of the DMA-mapped I/O buffer */
-#define US_SENSE_SIZE 18 /* Size of the autosense data buffer */
+#define US_SENSE_SIZE 22 /* Size of the autosense data buffer */
typedef int (*trans_cmnd)(struct scsi_cmnd *, struct us_data*);
typedef int (*trans_reset)(struct us_data*);
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