Hi Alan
We checked the command and data sent by a RedHat 9 Linux host. (EHCI).
After enumeration this is the sequence followed by Linux:
1. Test Unit Ready CSW returns 01 - command failed
2. Request sense
18 byte sense data is:
70 00 06 00 00 00 00 0A 00 00 00 00 28 00 00 00 00 00 (UNIT ATTENTION)
3. Test Unit Ready CSW returns 00 - command successful
4. Read Capacity: data returned is
00 0F 1E FF 00 00 02 00 implies LBA size = 512bytes and 400+
MB size?
5. Mode Sense :
Sense data: 03 00 00 00
6. Read (10) -- successful - 4096 bytes of data
We then try to follow the same sequence; First Test UNIT ready fails
(01).
2. Request sense yields the same result :
70 00 06 00 00 00 00 0A 00 00 00 00 28 00 00 00 00 00 (UNIT ATTENTION).
3. Second Test unit ready also fails.(01) So we wait in loop until it
becomes successful.
4. Request sense. Returns this .
70 00 00 00 00 00 00 0A 00 00 00 00 00 00 00 00 00 00
No error?.
4. Mode sense returns 4 bytes data.
5. Read (10) fails returns 01 in CSW.
Note that Read(10) no longer stalls. But simply fails. Please Advice..
Yours truly,
Vineeth
-----Original Message-----
From: Alan Stern [mailto:[EMAIL PROTECTED]
Sent: Tuesday, June 12, 2007 10:28 PM
To: Balan, Vineeth (IE10)
Cc: linux-usb-users@lists.sourceforge.net
Subject: RE: [usb-storage] Mass storage device NAK's
On Tue, 12 Jun 2007, Balan, Vineeth (IE10) wrote:
> Hi Alan
>
> We are not still able to get the device to respond .The command
> sequence that we are using:
>
> 1. Read 10 - response is STALL.
> We then clear feature command. And a Bulk in to retrieve the CSW of
> failed Read 10.
> 2. Request Sense: 18 bytes of sense data and CSW. Sense data shows 06
-
> UNIT Attention condition.
> 3. Read 10 Stall again.
>
> How do we resolve this issue? We are using an OHCI controller and the
> device is USB 2.0 compatible. Is this a factor?
No.
> Should we give a specific amount of time between a UNIT ATTENTION
> condition and next Read 10. We have also noted that all medium access
> commands fail but others like Read Capacity, TUR, is successful.
It's very frustrating trying to give you advice, because you rarely
follow it. So here are my suggestions:
1. Plug your device into a standard Linux system and use your
bus analyzer or usbmon to see what commands and data get
sent. Then see how it differs from your system and try
changing your system to match what Linux does.
2. Use a different test device. Some work better than others.
In fact, I don't remember if you have ever said what sort of
device you are using for your tests.
Alan Stern
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