This is a note to let you know that I've just added the patch titled
usb-storage: CY7C68300A chips do not support Cypress ATACB
to my usb git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-next branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will also be merged in the next major kernel release
during the merge window.
If you have any questions about this process, please let me know.
>From 671b4b2ba9266cbcfe7210a704e9ea487dcaa988 Mon Sep 17 00:00:00 2001
From: Tormod Volden <[email protected]>
Date: Sat, 20 Apr 2013 14:24:04 +0200
Subject: usb-storage: CY7C68300A chips do not support Cypress ATACB
Many cards based on CY7C68300A/B/C use the USB ID 04b4:6830 but only the
B and C variants (EZ-USB AT2LP) support the ATA Command Block
functionality, according to the data sheets. The A variant (EZ-USB AT2)
locks up if ATACB is attempted, until a typical 30 seconds timeout runs
out and a USB reset is performed.
https://bugs.launchpad.net/bugs/428469
It seems that one way to spot a CY7C68300A (at least where the card
manufacturer left Cypress' EEPROM default vaules, against Cypress'
recommendations) is to look at the USB string descriptor indices.
A http://media.digikey.com/pdf/Data%20Sheets/Cypress%20PDFs/CY7C68300A.pdf
B http://www.farnell.com/datasheets/43456.pdf
C http://www.cypress.com/?rID=14189
Note that a CY7C68300B/C chip appears as CY7C68300A if it is running
in Backward Compatibility Mode, and if ATACB would be supported in this
case there is anyway no way to tell which chip it really is.
For 5 years my external USB drive has been locking up for half a minute
when plugged in and ata_id is run by udev, or anytime hdparm or similar
is run on it.
Finally looking at the /correct/ datasheet I think I found the reason. I
am aware the quirk in this patch is a bit hacky, but the hardware
manufacturers haven't made it easy for us.
Signed-off-by: Tormod Volden <[email protected]>
Cc: stable <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/usb/storage/cypress_atacb.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)
diff --git a/drivers/usb/storage/cypress_atacb.c
b/drivers/usb/storage/cypress_atacb.c
index e4efc7b..8514a2d 100644
--- a/drivers/usb/storage/cypress_atacb.c
+++ b/drivers/usb/storage/cypress_atacb.c
@@ -248,14 +248,26 @@ static int cypress_probe(struct usb_interface *intf,
{
struct us_data *us;
int result;
+ struct usb_device *device;
result = usb_stor_probe1(&us, intf, id,
(id - cypress_usb_ids) + cypress_unusual_dev_list);
if (result)
return result;
- us->protocol_name = "Transparent SCSI with Cypress ATACB";
- us->proto_handler = cypress_atacb_passthrough;
+ /* Among CY7C68300 chips, the A revision does not support Cypress ATACB
+ * Filter out this revision from EEPROM default descriptor values
+ */
+ device = interface_to_usbdev(intf);
+ if (device->descriptor.iManufacturer != 0x38 ||
+ device->descriptor.iProduct != 0x4e ||
+ device->descriptor.iSerialNumber != 0x64) {
+ us->protocol_name = "Transparent SCSI with Cypress ATACB";
+ us->proto_handler = cypress_atacb_passthrough;
+ } else {
+ us->protocol_name = "Transparent SCSI";
+ us->proto_handler = usb_stor_transparent_scsi_command;
+ }
result = usb_stor_probe2(us);
return result;
--
1.8.1.rc1.5.g7e0651a
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