Re: [PATCH] usb-storage: Ignore UAS for LaCie Rugged FW USB3

[Tasos Sahanidis <tasos@tasossah.com>]

On 2024-02-09 17:31, Alan Stern wrote:
> On Fri, Feb 09, 2024 at 05:11:21PM +0200, Tasos Sahanidis wrote:
>> This external HDD fails when plugged in to a USB 3 port. Ignoring UAS and
>> falling back to mass storage resolves this issue.
> 
> What happens when it is plugged into a USB-2 port?

It works without any quirks over USB 2.0 with uas, however asking for
cache data fails gracefully.

[  520.829840] scsi host4: uas
[  521.024643] scsi 4:0:0:0: Direct-Access     LaCie    Rugged FW USB3   1081 PQ: 0 ANSI: 4
[  521.026370] sd 4:0:0:0: Attached scsi generic sg2 type 0
[  521.030096] sd 4:0:0:0: [sdc] 976773153 512-byte logical blocks: (500 GB/466 GiB)
[  521.030369] sd 4:0:0:0: [sdc] Write Protect is off
[  521.030373] sd 4:0:0:0: [sdc] Mode Sense: 47 00 10 08
[  521.030507] sd 4:0:0:0: [sdc] Asking for cache data failed
[  521.030512] sd 4:0:0:0: [sdc] Assuming drive cache: write through
[  521.065916]  sdc: sdc1
[  521.067783] sd 4:0:0:0: [sdc] Attached SCSI disk
[  521.699380] EXT4-fs (sdc1): recovery complete
[  521.699388] EXT4-fs (sdc1): mounted filesystem with ordered data mode. Opts: errors=remount-ro. Quota mode: none.

> Have you checked to see if any of the quirk flags can prevent this 
> problem?  It looks like the only issue might be that one Mode Sense(6) 
> command.

I have tried various combinations of all the available quirks and I
couldn't get it to not hang. Without any quirks it keeps retrying Mode
Sense(6) constantly.

I tested US_FL_ALWAYS_SYNC as it sets sdev->skip_ms_page_8 (both with
and without US_FL_NO_REPORT_OPCODES | US_FL_NO_SAME), and it hung at an
ATA passthrough command; presumably the next step afterwards.

30 seconds and one USB reset later, the disk is recognised, but I
do not know if it is reliable.

[  329.161316] scsi 4:0:0:0: Direct-Access     LaCie    Rugged FW USB3   1081 PQ: 0 ANSI: 4
[  329.162228] sd 4:0:0:0: Attached scsi generic sg2 type 0
[  329.166650] sd 4:0:0:0: [sdc] 976773153 512-byte logical blocks: (500 GB/466 GiB)
[  329.166654] sd 4:0:0:0: [sdc] Assuming Write Enabled
[  329.166655] sd 4:0:0:0: [sdc] Assuming drive cache: write back
[  329.197983]  sdc: sdc1
[  329.198521] sd 4:0:0:0: [sdc] Attached SCSI disk
[  359.553806] sd 4:0:0:0: [sdc] tag#3 uas_eh_abort_handler 0 uas-tag 1 inflight: IN
[  359.553816] sd 4:0:0:0: [sdc] tag#3 CDB: ATA command pass through(12)/Blank a1 08 2e 00 01 00 00 00 00 ec 00 00
[  359.573771] scsi host4: uas_eh_device_reset_handler start
[  359.702116] usb 3-1: reset SuperSpeed USB device number 3 using xhci_hcd
[  359.722068] usb 3-1: LPM exit latency is zeroed, disabling LPM.
[  359.724348] scsi host4: uas_eh_device_reset_handler success
[  360.582975] EXT4-fs (sdc1): recovery complete
[  360.633098] EXT4-fs (sdc1): mounted filesystem with ordered data mode. Opts: errors=remount-ro. Quota mode: none.

My assumption is that something goes wrong during init and that makes it
hang in general. Perhaps the Mode Sense(6) is broken in addition to
whatever else is misbehaving. I don't believe the XHCI controller is at
fault.

> Falling back from uas to usb-storage could reduce the throughput 
> considerably.  We would like to avoid doing this if possible.

Absolutely, but at the same time I am not sure how much it matters for
an old mechanical hard disk. Granted, someone can use the same enclosure
and install an SSD internally, so perhaps that makes it worth it.

Thanks

--
Tasos