From: Tormod Volden <debian.tormod@xxxxxxxxx> 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. Signed-off-by: Tormod Volden <debian.tormod@xxxxxxxxx> --- Hi, 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. Please cc me because I am not subscribed to the list. Best regards, Tormod 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 5410464..02e55c0 100644 --- a/drivers/usb/storage/cypress_atacb.c +++ b/drivers/usb/storage/cypress_atacb.c @@ -249,14 +249,26 @@ 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; -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
