Re: S3 Resume working, but IDE disk hung

[Pavel Machek <pavel-+ZI9xUNit7I@public.gmane.org>]

Hi!

> > [Note, you should look at the patch "to prevent data corruption". It
> > could do the trick. At least it should be good as a base.
> > 
> > > Prior to suspend one needs to :
> > > 
> > > 	block all new coming requests.
> > > 	flush cache and wait for return.
> > > 	disable DMA, and switch to PIO 0.
> > 
> > Why would you want to switch off DMA and go PIO 0?
> 
> Because it is a known state when we drop out of the driver.
> 99% of the failures of ACPI (please read the fine print, where it requires
> discrete access to "task file registers") is not knowing where or what
> stated the device and driver is set in.
> 
> The reality is it does not matter if it is in PIO 0 to the hardware, but
> setting the values in the kernel so it knows what to do is critical.
> 
> > As long as DMA is not happening (that is not disabled, we just don't
> > ask drive to do it), you should be fine.
>                        ^^^^^^^^^^^^^^^^^^
> 
> Should does not cut it, period.
> Either you are or are not correct.

Which spec does specify it needs to be in PIO0? I don't want to read
between the lines.

Actually, working around broken ACPI is probably good idea. And as
Ducrot Bruno <ducrot-kk6yZipjEM5g9hUCZPvPmw@public.gmane.org> shown, such broken ACPI exists.

> > > Resume requires calling :
> > > 
> > > 	"do_reset()"
> > > 	for (;;)
> > > 		if ((check_power()) == active)
> > > 			break;
> > > 	"piix_config_drive_xfer_rate()" 
> > > 	unblock request pathway.
> > 
> > You don't need to block/unblock request pathways. kernel/suspend.c
> > takes care of that.
> 
> Really, try sending a command to a drive when it is not ready.  Try send
> it to after a sleep, and watch it eat the command and hang the bus.

You can't send a command to the drive when not ready, because there's
noone there to generate request. If there is one, you have bigger
problems than that.

> It really seems like you can not or will not listen to real-documented
> logical concerns.  So please do as you wish and push it through, it does
> not bother me.  It will give me another chance to blast Linus and
> deflect

Okay. What's in there in 2.5.41 is fine with me (at least it does not
eat disks any more). Doing while check_power() and going PIO 0 seems
like good idea, and if someone wishes to add it, good luck for
him. blocking/unblocking request pathways is bad idea and is not
needed.
								Pavel
-- 
When do you have heart between your knees?


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