Hi,
I'm trying to understand how the USB Mass Storage Device
works in 2.6. Specifically 2.6.14. I see a fair amount of
churn in this subsystem.
My principle concern/question is how does data from a file
on the filesystem get transported to a memory stick? I
have dumped info at many stages and see varying URB buffers
sent out.
My device is using PIO not DMA. The HCD controller
understands this, but under hcd_alloc_buffer it choses to
simply kmalloc what the Usb Mass Storage device asks for.
This happens to be 64bytes as per:
-----------------------------
* We provide a DMA-mapped I/O buffer for use with small
USB transfers.
* It turns out that CB[I] needs a 12-byte buffer and
Bulk-only needs a
* 31-byte buffer. But Freecom needs a 64-byte buffer, so
that's the
* size we'll allocate.
-----------------------------
As I try to trace through the use of this, I see that the
following flags are changing depending on various SCSI
activity to the memory stick:
-----------------------------
# pehci urb_enqueue: URB:0xef708338 TxFlags:0xc
TxBuff:0xee110000 of 31 bytes [0x55 0x53 0x42
0x43...]
pehci urb_enqueue: URB:0xef7084e8 TxFlags:0x5
TxBuff:0xc240a098 of 36 bytes [0x00 0x00 0x00
0x00...]
pehci urb_enqueue: URB:0xef708338 TxFlags:0xc
TxBuff:0xee110000 of 13 bytes [0x55 0x53 0x42
0x43...]
Vendor: USB Model: Flash Disk Rev: 2.00
Type: Direct-Access ANSI SCSI
revision: 02
pehci urb_enqueue: URB:0xef708338 TxFlags:0xc
TxBuff:0xee110000 of 31 bytes [0x55 0x53 0x42
0x43...]
pehci urb_enqueue: URB:0xef708338 TxFlags:0xc
TxBuff:0xee110000 of 13 bytes [0x55 0x53 0x42
0x43...]
pehci urb_enqueue: URB:0xef708338 TxFlags:0xc
TxBuff:0xee110000 of 31 bytes [0x55 0x53 0x42
0x43...]
pehci urb_enqueue: URB:0xef7084e8 TxFlags:0x5
TxBuff:0xefbee03c of 8 bytes [0x00 0x00 0x00
0x00...]
pehci urb_enqueue: URB:0xef708338 TxFlags:0xc
TxBuff:0xee110000 of 13 bytes [0x55 0x53 0x42
0x43...]
SCSI device sdb: 127840 512-byte hdwr sectors (65 MB)
pehci urb_enqueue: URB:0xef708338 TxFlags:0xc
TxBuff:0xee110000 of 31 bytes [0x55 0x53 0x42
0x43...]
pehci urb_enqueue: URB:0xef7084e8 TxFlags:0x5
TxBuff:0xefbee03c of 192 bytes [0x00 0x00 0x00
0x00...]
drivers/usb/pehcd/host/pehci.c: ISP1761 HCD: Error -
SHORT-READ-NOT-OK : length 12 (expected 192)
ATL: IN PAYLOAD DATA from 0x00001100 to 0xefbee03c (12) [0b
00 00 08...] (URB_SHORT_NOT_OK)
0x0b, 0x00, 0x00, 0x08
0x00, 0x03, 0xe3, 0x11
0x00, 0x00, 0x08, 0x00
pehci urb_enqueue: URB:0xef708338 TxFlags:0xc
TxBuff:0xee110000 of 13 bytes [0x55 0x53 0x42
0x43...]
sdb: Write Protect is off
sdb: assuming drive cache: write through
pehci urb_enqueue: URB:0xef708338 TxFlags:0xc
TxBuff:0xee110000 of 31 bytes [0x55 0x53 0x42
0x43...]
pehci urb_enqueue: URB:0xef708338 TxFlags:0xc
TxBuff:0xee110000 of 13 bytes [0x55 0x53 0x42
0x43...]
pehci urb_enqueue: URB:0xef708338 TxFlags:0xc
TxBuff:0xee110000 of 31 bytes [0x55 0x53 0x42
0x43...]
pehci urb_enqueue: URB:0xef708338 TxFlags:0xc
TxBuff:0xee110000 of 13 bytes [0x55 0x53 0x42
0x43...]
pehci urb_enqueue: URB:0xef708338 TxFlags:0xc
TxBuff:0xee110000 of 31 bytes [0x55 0x53 0x42
0x43...]
pehci urb_enqueue: URB:0xef708338 TxFlags:0xc
TxBuff:0xee110000 of 13 bytes [0x55 0x53 0x42
0x43...]
pehci urb_enqueue: URB:0xef708338 TxFlags:0xc
TxBuff:0xee110000 of 31 bytes [0x55 0x53 0x42
0x43...]
pehci urb_enqueue: URB:0xef7084e8 TxFlags:0x5
TxBuff:0xefbee03c of 8 bytes [0x00 0x00 0x00
0x00...]
pehci urb_enqueue: URB:0xef708338 TxFlags:0xc
TxBuff:0xee110000 of 13 bytes [0x55 0x53 0x42
0x43...]
SCSI device sdb: 127840 512-byte hdwr sectors (65 MB)
pehci urb_enqueue: URB:0xef708338 TxFlags:0xc
TxBuff:0xee110000 of 31 bytes [0x55 0x53 0x42
0x43...]
pehci urb_enqueue: URB:0xef7084e8 TxFlags:0x5
TxBuff:0xefbee03c of 192 bytes [0x00 0x00 0x00
0x00...]
drivers/usb/pehcd/host/pehci.c: ISP1761 HCD: Error -
SHORT-READ-NOT-OK : length 12 (expected 192)
ATL: IN PAYLOAD DATA from 0x00001100 to 0xefbee03c (12) [0b
00 00 08...] (URB_SHORT_NOT_OK)
0x0b, 0x00, 0x00, 0x08
0x00, 0x03, 0xe3, 0x11
0x00, 0x00, 0x08, 0x00
.....
-----------------------------
When I actually transfer file contents, I see the buffer
sizes increase dramaitcally:
-----------------------------
pehci urb_enqueue: URB:0xef7080b0 TxFlags:0x5
TxBuff:0xc2a40000 of 20480 bytes [0x33 0xcd 0xa9
0x71...]
pehci urb_enqueue: URB:0xef708338 TxFlags:0xc
TxBuff:0xee110000 of 13 bytes [0x55 0x53 0x42
0x43...]
pehci urb_enqueue: URB:0xef708338 TxFlags:0xc
TxBuff:0xee110000 of 31 bytes [0x55 0x53 0x42
0x43...]
pehci urb_enqueue: URB:0xef70811c TxFlags:0x5
TxBuff:0xc2a45000 of 36864 bytes [0xef 0xd0 0xa3
0x42...]
pehci urb_enqueue: URB:0xef708338 TxFlags:0xc
TxBuff:0xee110000 of 13 bytes [0x55 0x53 0x42
0x43...]
pehci urb_enqueue: URB:0xef708338 TxFlags:0xc
TxBuff:0xee110000 of 31 bytes [0x55 0x53 0x42
0x43...]
pehci urb_enqueue: URB:0xef70811c TxFlags:0x5
TxBuff:0xefa46800 of 512 bytes [0x00 0x00 0x00
0x00...]
pehci urb_enqueue: URB:0xef708338 TxFlags:0xc
TxBuff:0xee110000 of 13 bytes [0x55 0x53 0x42
0x43...]
pehci urb_enqueue: URB:0xef708338 TxFlags:0xc
TxBuff:0xee110000 of 31 bytes [0x55 0x53 0x42
0x43...]
pehci urb_enqueue: URB:0xef70811c TxFlags:0x5
TxBuff:0xefa46a00 of 512 bytes [0x00 0x00 0x00
0x00...]
pehci urb_enqueue: URB:0xef708338 TxFlags:0xc
TxBuff:0xee110000 of 13 bytes [0x55 0x53 0x42
0x43...]
pehci urb_enqueue: URB:0xef708338 TxFlags:0xc
TxBuff:0xee110000 of 31 bytes [0x55 0x53 0x42
0x43...]
I'm curious how the TxFlags keep changing... these are
combinations of:
-----------------------------
#define URB_SHORT_NOT_OK 0x0001 /* report short reads as
errors */
#define URB_ISO_ASAP 0x0002 /* iso-only, urb->start_frame
ignored */
#define URB_NO_TRANSFER_DMA_MAP 0x0004 /* urb->transfer_dma
valid on submit */
#define URB_NO_SETUP_DMA_MAP 0x0008 /* urb->setup_dma valid
on submit */
#define URB_NO_FSBR 0x0020 /* UHCI-specific */
#define URB_ZERO_PACKET 0x0040 /* Finish bulk OUTs with
short packet */
#define URB_NO_INTERRUPT 0x0080 /* HINT: no non-error
interrupt needed */
-----------------------------
I only see the flags non-zero once the SCSI system start
discoverying the memorystick. Previous URB enqueues are
all zero for the most part.
My present situation is that after transfering files I see
file contents that are corrupt, along with system
instability.
I'm trying to isolate if I'm indeed copying correclty to
and from memory.
I see DMA-based HCDs use pools of data. For non DMA based
HCDs I see accomodations have been made in teh hcd.c
allocation system. But wonder if the SCSI USB Mass Storage
device works with this in mind?
I would also like to figure out if/why the flags for DMA
transfers are fluctuating so much... and specifically the
logic behind this snippet:
-----------------------------
/* we assume that if transfer_buffer isn't us->iobuf then
it
* hasn't been mapped for DMA. Yes, this is clunky, but
it's
* easier than always having the caller tell us whether
the
* transfer buffer has already been mapped. */
us->current_urb->transfer_flags = URB_NO_SETUP_DMA_MAP;
if (us->current_urb->transfer_buffer == us->iobuf)
us->current_urb->transfer_flags |=
URB_NO_TRANSFER_DMA_MAP;
us->current_urb->transfer_dma = us->iobuf_dma;
us->current_urb->setup_dma = us->cr_dma;
-----------------------------
I'm missing something here... I'm just trying to figure out
where I SHOULD be reading & writing from in memory as I'm
presently not and its blowing up whenever the SCSI system
notices my memory stick.
Any help much appreciated.
Mike.
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