On Sat, 5 Aug 2023 at 18:29, Damien Le Moal <dlemoal@xxxxxxxxxx> wrote:
>
> - Prevent the scsi disk driver from issuing a START STOP UNIT command
> for ATA devices during system resume as this causes various issues
> reported by multiple users.
Honestly, this seems pretty broken.
I mean, there are literally just three things that manage_start_stop
does, and you just disabled one of those cases.
And it's quite illogical, since one of the two remaining cases is for
the suspend side (the final one is shutdown).
The deeper issue seems to be that ATA is just doing something that
other SCSI devices aren't doing (the whole set
'sdev->manage_start_stop' thing), and while there is one other user in
the sbp2 firewire code, clearly the SCSI people don't really care for
this bit, and the SCSI changes then cause problems.
I agree that the new "don't ask sd.c to send a start command" is the
right thing to do, but I feel it was done in a particularly ugly and
illogical manner.
I think it would have been better if maybe the approach would have been to
(a) split manage_start_stop into three bits for the three actual
cases it deals with: (stop_on_suspend, stop_on_shutdown,
start_on_resume).
(b) then not set the "start_on_resume" bit
instead of the current crazy model of first saying "please manage
start/stop for me" and then following up with "oh, but don't do it for
this case".
See what I'm saying? Don't mix "please do X, but don't do subset Y"
bits. It's a completely messy thing and makes it really hard to figure
out what you actually want for no good reason.
I've pulled this, but it really smells like a maintenance disaster to
me. Particularly since the SCSI people really don't care about ATA
anyway.
Linus
