Re: [PATCH v2 1/2] usb: uas: implement .change_queue_depth to allow per-device queue depth override

[Luca Cecchi <luca.cecchi.info@gmail.com>]

Hi Oliver, Alan,

(Resending in plain text - my previous reply went out as HTML and got bounced
by the list software. Apologies for the noise if it reaches you twice.)

Quick status update before sending v3. Both pending items are already fixed
locally: dropped the qdepth-guard per Oliver's note (that's a separate general
issue, not something this patch should carry a workaround for), and trimmed
the comment per Alan's feedback.

While re-validating today, something changed the picture: repeating our
original load test (the one that found the safe queue-depth threshold)
against the exact same Lexar ES3 unit, but now also on Windows with a
completely different driver stack (UASPStor, not Linux's uas), reproduces the
same command-timeout/reset behavior we'd previously only seen on Linux. Since
the physical drive/bridge is the only thing in common between the two
reproductions, this points to the test unit itself having degraded since our
first round of testing on Oct 4, rather than anything in the driver or the
patch.

We'd rather not send v3 until we can re-validate it properly, which isn't
meaningful right now if the hardware itself is behaving inconsistently. We'll
follow up once we've sorted out whether this drive is still usable for
testing - hopefully it hasn't given up on us for good.

Thanks again for the time and the careful feedback on this, it's genuinely
appreciated.

Luca