powerbook hang from post-sleep cdrom access - fix

powerbook hang from post-sleep cdrom access - fix

[Joseph Garcia]

I think I have a fix to prevent a system hang when trying to access a cdrom
after sleeping.  I have a small util "wakebay" that simply does a
CDROM_MEDIA_CHANGED ioctl on a specified device.  I added a the line "wakebay
/dev/hdc" to PMUD's wakeup script on my PDQ.  This seems to get the desired
response from the drive, in that it locks the door and spins the disk when it
should, and if its not there, mounted, or otherwise, does nothing.

my code can be grabbed from http://www.execpc.com/~jpgarcia

Can this be done automatically at the kernel level?

Thanks.

--
Joseph P. Garcia      jpgarcia@execpc.com      jpgarcia@lidar.ssec.wisc.edu
CS Undergraduate                      Student Employee - Systems Programmer
University of Wisconsin - Madison                            UW Lidar Group

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Re: powerbook hang from post-sleep cdrom access - fix

[Stephan Leemburg]

Thanks!

I wil put the code also in pmud itself. This should in fact be done at
kernel level, so a patch will be needed for the current tree.

Joseph Garcia wrote:
>
> I think I have a fix to prevent a system hang when trying to access a cdrom
> after sleeping.  I have a small util "wakebay" that simply does a
> CDROM_MEDIA_CHANGED ioctl on a specified device.  I added a the line "wakebay
> /dev/hdc" to PMUD's wakeup script on my PDQ.  This seems to get the desired
> response from the drive, in that it locks the door and spins the disk when it
> should, and if its not there, mounted, or otherwise, does nothing.
>
> my code can be grabbed from http://www.execpc.com/~jpgarcia
>
> Can this be done automatically at the kernel level?
>
> Thanks.
>
> --
> Joseph P. Garcia      jpgarcia@execpc.com      jpgarcia@lidar.ssec.wisc.edu
> CS Undergraduate                      Student Employee - Systems Programmer
> University of Wisconsin - Madison                            UW Lidar Group

--
Stephan

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Re: powerbook hang from post-sleep cdrom access - fix

[Joseph Garcia]

Stephan Leemburg wrote:
> I wil put the code also in pmud itself. This should in fact be done at
> kernel level, so a patch will be needed for the current tree.

So would this always be done on wake to hdc and hde?  I read Pismos, and maybe
iBooks, have their drives at hde.  I'm not sure if they are afflicted by this
problem.

might also need to consider ide-floppy drives, like ls-120 and zip.  I don't
have one myself, so I don't know if these need it either.  They dont have much
for ioctls, just eject.  If they have this problem, an ioctl to
idefloppy_media_change may be needed.

I'm not concerned about it, but might genuine floppies have the hang problem
too?

I assume a bay hard drive would error/exit without a problem because they can't
change.

--
Joseph P. Garcia      jpgarcia@execpc.com      jpgarcia@lidar.ssec.wisc.edu
CS Undergraduate                      Student Employee - Systems Programmer
University of Wisconsin - Madison                            UW Lidar Group

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Re: powerbook hang from post-sleep cdrom access - fix

[Benjamin Herrenschmidt]

>
>So would this always be done on wake to hdc and hde?  I read Pismos, and
maybe
>iBooks, have their drives at hde.  I'm not sure if they are afflicted by this
>problem.

That's why this should be done from the kernel, I beleive. There, you can
know if the controller is hosting a hard disk, a cdrom or an ATAPI floppy.

>might also need to consider ide-floppy drives, like ls-120 and zip.  I don't
>have one myself, so I don't know if these need it either.  They dont
have much
>for ioctls, just eject.  If they have this problem, an ioctl to
>idefloppy_media_change may be needed.

Yep, probably, I'm not sure about those since I don't have one to test
with. I'm also considering adding code for force a disk access (spin up)
before trying to do the set features on wakeup.

>I'm not concerned about it, but might genuine floppies have the hang problem
>too?
>
>I assume a bay hard drive would error/exit without a problem because they
>can't
>change.


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Re: powerbook hang from post-sleep cdrom access - fix

[Robert Thompson]

>
> Stephan Leemburg wrote:
> > I wil put the code also in pmud itself. This should in fact be done at
> > kernel level, so a patch will be needed for the current tree.
>
> So would this always be done on wake to hdc and hde?  I read Pismos, and
maybe
> iBooks, have their drives at hde.  I'm not sure if they are afflicted by
this
> problem.

I have an iBook... the hard drive is /dev/hda, the CD-ROM is /dev/hdc. Same
thing on the G4 at home, not that that matters right now...

Later,
Robbie


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Re: powerbook hang from post-sleep cdrom access - fix

[Michael Schmitz]

> I think I have a fix to prevent a system hang when trying to access a cdrom
> after sleeping.  I have a small util "wakebay" that simply does a
> CDROM_MEDIA_CHANGED ioctl on a specified device.  I added a the line "wakebay
> /dev/hdc" to PMUD's wakeup script on my PDQ.  This seems to get the desired
> response from the drive, in that it locks the door and spins the disk when it
> should, and if its not there, mounted, or otherwise, does nothing.
>
> my code can be grabbed from http://www.execpc.com/~jpgarcia
>
> Can this be done automatically at the kernel level?

Should be called from the IDE notify chain perhaps. See the last function
in ide-pmac().

	Michael


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Re: powerbook hang from post-sleep cdrom access - fix

[Benjamin Herrenschmidt]

>
>Should be called from the IDE notify chain perhaps. See the last function
>in ide-pmac().

Yep, this should be done juste before the pmac_ide_dma_onoff() call in
ide-pmac.c/idepmac_notify_sleep(). It should be done regardless of the
disk beeing in a bay or not since new machines will ultimately support
sleep on desktop boxes too. Something like

switch(drive->media) {
  case ide_disk:
    // spin up the disk
    break;
  case ide_cdrom:
    // do whatever you need here
    break;
  case ide_floppy:
    // do whatever you need here
    break;
}

Note that at his point, IDE interrupts have been re-enabled, so we should
be careful about the way the IDE layer is called from here.


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Re: powerbook hang from post-sleep cdrom access - fix

[Michael Schmitz]

> >Should be called from the IDE notify chain perhaps. See the last function
> >in ide-pmac().
>
> Yep, this should be done juste before the pmac_ide_dma_onoff() call in
> ide-pmac.c/idepmac_notify_sleep(). It should be done regardless of the
> disk beeing in a bay or not since new machines will ultimately support
> sleep on desktop boxes too. Something like
>
> switch(drive->media) {
>   case ide_disk:
>     // spin up the disk

Aye. Can you be more specific about 'do whatever needs to be done'? Can I
just send the disk a read command to wake it up? Send a reset
command?? Will a reset command hurt if I always send a drive reset
there?
I'll try that on my Lombard to see if I can save the nasty timeout when
the drive was powered off with hdparm -Y ?? That would help fake sleep
mode on the Pismo, or did you implement pmu sleep/wakeup there yet?

	Michael


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Re: powerbook hang from post-sleep cdrom access - fix

[Benjamin Herrenschmidt]

>Aye. Can you be more specific about 'do whatever needs to be done'? Can I
>just send the disk a read command to wake it up? Send a reset
>command?? Will a reset command hurt if I always send a drive reset
>there?

I don't know yet ;) I have to look more closely at my ATA spec. It may
not be necessary to wakeup the disk in fact, the current code seems to be
ok for the hard disk once the timeout has been bumped.

What bugs me is that on wakeup, the CD-ROM should automatically send a
request unit attention on the first command to signal a disk change. So
in theory, sending the media change command should not be necessary.
Well, it can do no harm, I'll see what can be done.

>I'll try that on my Lombard to see if I can save the nasty timeout when
>the drive was powered off with hdparm -Y ?? That would help fake sleep
>mode on the Pismo, or did you implement pmu sleep/wakeup there yet?

Not yet, i've not yet figured out all the details, this machine seems to
be more complicated to put to sleep (and to wakeup) than older ones, and,
as usual, I have absolutely no docs nor specs.

Ben.


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Re: powerbook hang from post-sleep cdrom access - fix

[Michael Schmitz]

> >Aye. Can you be more specific about 'do whatever needs to be done'? Can I
> >just send the disk a read command to wake it up? Send a reset
> >command?? Will a reset command hurt if I always send a drive reset
> >there?
>
> I don't know yet ;) I have to look more closely at my ATA spec. It may
> not be necessary to wakeup the disk in fact, the current code seems to be
> ok for the hard disk once the timeout has been bumped.

Except that when the disk has been shut down with hdparm -Y, it needs a
reset and that will only come after quite some number of retries ans
timeouts. Not for the faint of heart :-)

Let me know when you have some code to test. I can test with CD-ROM and
Zip in the media bay as well BTW. Are your current changes in Paul's
stable tree or in the bk stable only? Six rsync trees is a bit much for me
to manage :-)

XFree86 related PCI resource diff follows separate.

	Michael


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Re: powerbook hang from post-sleep cdrom access - fix

[Joseph Garcia]

Michael Schmitz wrote:
> Aye. Can you be more specific about 'do whatever needs to be done'? Can I
> just send the disk a read command to wake it up? Send a reset
> command?? Will a reset command hurt if I always send a drive reset
> there?

My expirience is that just reading the drive causes a problem, much like
userspace trying to read it.  there is also the door locking feature that I
suppose could be done explicitly on wakeup if mounted.  I dont know what else a
"media change" ctl entails, but it seems to do enough to get the cdrom back to
where it left off.

> I'll try that on my Lombard to see if I can save the nasty timeout when
> the drive was powered off with hdparm -Y ?? That would help fake sleep
> mode on the Pismo, or did you implement pmu sleep/wakeup there yet?

My wallstreet has the same problem.  it has to reset the whole ide bus to get it
going again.  rather, i use hdparm -y, which just puts it in standby rather than
sleep.  When the drive does a normal hardware-timeout sleep, it seems to do
this, since it doesn't require a reset to wake up.

Last I remember, the result to when it resets the bus so it can wake up from a
-Y, the flaky 8G (DYLA) drive is set in such a way that it can then wake up
correctly from -Y. I recall that unmaskirq should be one way for the 8G, but
upon the reset, its the other way.  my current 6G (from brother's upgraded
lombard) seems to always time out in my PDQ (at wakeup, using_dma varies,
unmaskirq is always off).  judging by message log, its another lost interrupt
problem.  It would make sense.  8G - reset, regains irq, wake normally.  6G -
reset, still no irq when drive eventually wakes.

heres two sequential wakes from -Y sleep with the 6G in my PDQ

Jul 27 10:48:07 momiji kernel: hda: lost interrupt
Jul 27 10:48:07 momiji kernel: hda: dma_intr: status=0xd0 { Busy }
Jul 27 10:48:07 momiji kernel: ide0: reset: success
Jul 27 10:48:33 momiji kernel: hda: irq timeout: status=0xd0 { Busy }
Jul 27 10:48:33 momiji kernel: ide0: reset: success

sidenote, a powerbook hard drive compatibility grid can be found at
http://www01.u-page.so-net.ne.jp/ba2/nsxt/faq1E.html

--
Joseph P. Garcia      jpgarcia@execpc.com      jpgarcia@lidar.ssec.wisc.edu
CS Undergraduate                      Student Employee - Systems Programmer
University of Wisconsin - Madison                            UW Lidar Group

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Re: powerbook hang from post-sleep cdrom access - fix

[Michael Schmitz]

> > Aye. Can you be more specific about 'do whatever needs to be done'? Can I
> > just send the disk a read command to wake it up? Send a reset
> > command?? Will a reset command hurt if I always send a drive reset
> > there?
>
> My expirience is that just reading the drive causes a problem, much like
> userspace trying to read it.  there is also the door locking feature that I
> suppose could be done explicitly on wakeup if mounted.  I dont know what else a
> "media change" ctl entails, but it seems to do enough to get the cdrom back to
> where it left off.

OK, that seems to mean wherever we can safely send the drive a reset
command after sleep, we should do that. Now under what conditions will a
reset command mess up things beyond recovery? Is it possible to sleep the
machine while the IDE drive has a request under service?

	Michael


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Re: powerbook hang from post-sleep cdrom access - fix

[Joseph Garcia]

Michael Schmitz wrote:
> > My expirience is that just reading the drive causes a problem, much like
> > userspace trying to read it.  there is also the door locking feature that I
> > suppose could be done explicitly on wakeup if mounted.  I dont know what else a
> > "media change" ctl entails, but it seems to do enough to get the cdrom back to
> > where it left off.
>
> OK, that seems to mean wherever we can safely send the drive a reset
> command after sleep, we should do that. Now under what conditions will a
> reset command mess up things beyond recovery? Is it possible to sleep the
> machine while the IDE drive has a request under service?

ide-pmac resets all non-mediabay (non-CD?) ide drives on wake.
(idepmac_wake_disk)

looking at the mediabay code, the media bay (at least when containing a CD)
seems to be reset.  (set_media_bay is called, feature_set(reset) is called on
the bay, messages confirms call to set_media_bay with a "kernel: media bay 0
contains a CD-ROM drive" on wake).  are IDE-floppies handled by the mediabay's
CD code as well?

By mutual exclusion, it would appear we already reset ide devices upon wake.
the media change call may be what we need to get the removable media to re-init
their status.  I did get the following VFS message, which may cause concern.

Jul 27 12:00:01 momiji pmud[330]: system awake again
Jul 27 12:00:01 momiji pmud[330]: running /etc/power/pwrctl wakeup ac
Jul 27 12:00:01 momiji pwrctl: calling /etc/power/pwrctl-local wakeup ac
Jul 27 12:00:01 momiji kernel: VFS: busy inodes on changed media.

PMUD does a sync right before signalling to sleep, so most activity is reduced.
I think the rest tends to be handled by the kernel's sleep with interrupts
disabled, etc.

I noticed in browsing the kernel code, there is a file operation called
revalidate, which takes the same params as check_media_change.  cdrom.c does not
define this.  Would this be a route worth pursuing over the media change
solution?

--
Joseph P. Garcia      jpgarcia@execpc.com      jpgarcia@lidar.ssec.wisc.edu
CS Undergraduate                      Student Employee - Systems Programmer
University of Wisconsin - Madison                            UW Lidar Group

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Re: powerbook hang from post-sleep cdrom access - fix

[Michael Schmitz]

> > OK, that seems to mean wherever we can safely send the drive a reset
> > command after sleep, we should do that. Now under what conditions will a
> > reset command mess up things beyond recovery? Is it possible to sleep the
> > machine while the IDE drive has a request under service?
>
> ide-pmac resets all non-mediabay (non-CD?) ide drives on wake.
> (idepmac_wake_disk)

Fine, so that shouldn't be it.

> looking at the mediabay code, the media bay (at least when containing a CD)
> seems to be reset.  (set_media_bay is called, feature_set(reset) is called on
> the bay, messages confirms call to set_media_bay with a "kernel: media bay 0

I don't think that's the IDE device reset, just a reset for the media bay
controller (or the IDE controller) itself.

> contains a CD-ROM drive" on wake).  are IDE-floppies handled by the mediabay's
> CD code as well?

IDE-floppies in the media bay should be handled by that code.

> Jul 27 12:00:01 momiji kernel: VFS: busy inodes on changed media.

That might be a problem - the mediachange call might conflict with the VFS
still holding open channels to the device?

> PMUD does a sync right before signalling to sleep, so most activity is reduced.
> I think the rest tends to be handled by the kernel's sleep with interrupts
> disabled, etc.
>
> I noticed in browsing the kernel code, there is a file operation called
> revalidate, which takes the same params as check_media_change.  cdrom.c does not
> define this.  Would this be a route worth pursuing over the media change
> solution?

You know, I just remebered the same revalidate call. It's used for disks
when the partition table was changed, and I recall it fails when there are
other open channels to the disk as well. Moreover, check_media_change
should _check_ for media change, not behave as if the media changed (which
may be difficult to do across a sleep if the CD-ROM always reportss 'maybe
the media was changed while I was asleep'. In that case, maybe reading in
the superblock and comparing it with a cached copy should be done (that's
so obvious, it may have been implemented ten years ago :-).

	Michael


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Re: powerbook hang from post-sleep cdrom access - fix

[Benjamin Herrenschmidt]

>> looking at the mediabay code, the media bay (at least when containing a CD)
>> seems to be reset.  (set_media_bay is called, feature_set(reset) is
>called on
>> the bay, messages confirms call to set_media_bay with a "kernel: media
bay 0
>
>I don't think that's the IDE device reset, just a reset for the media bay
>controller (or the IDE controller) itself.

There should also be a reset of the disk itself (via the reset line).

>That might be a problem - the mediachange call might conflict with the VFS
>still holding open channels to the device?

Yep. That's a "generic" problem with the current sleep code (and with
media-bay removal in general). linux 2.2 is not really prepared to handle
hot-swap of IDE disks.

>You know, I just remebered the same revalidate call. It's used for disks
>when the partition table was changed, and I recall it fails when there are
>other open channels to the disk as well. Moreover, check_media_change
>should _check_ for media change, not behave as if the media changed (which
>may be difficult to do across a sleep if the CD-ROM always reportss 'maybe
>the media was changed while I was asleep'. In that case, maybe reading in
>the superblock and comparing it with a cached copy should be done (that's
>so obvious, it may have been implemented ten years ago :-).

In any way, I still have my problem of setting nIEN in the IDE control
register of some powerbooks causing a hang of the entire machine (bus not
ack'ing ?). Other IDE registers work fine and the IDE control register
seems to work fine in normal conditions, the hang only happens when
setting this inside my set_feature code. I'm wondering if it's due to a
very crappy CD-ROM drive, a very-crappy Apple home-made IDE controller,
or be missing something obvious...

Ben.

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