Re: sata suspend resume ...

[Jeff Garzik <jeff@garzik.org>]

Hugh Dickins wrote:
> --- 2.6.17-rc2/drivers/scsi/libata-core.c	2006-04-19 09:14:11.000000000 +0100
> +++ linux/drivers/scsi/libata-core.c	2006-04-21 20:55:48.000000000 +0100
> @@ -4288,6 +4288,7 @@ int ata_device_resume(struct ata_port *a
>  {
>  	if (ap->flags & ATA_FLAG_SUSPENDED) {
>  		ap->flags &= ~ATA_FLAG_SUSPENDED;
> +		ata_busy_sleep(ap, ATA_TMOUT_BOOT_QUICK, ATA_TMOUT_BOOT);
>  		ata_set_mode(ap);
>  	}


This is helpful to narrow down the problem, but its a bit of a layering 
violation.  In the current code, all functions called by 
ata_device_{suspend,resume}() are high level functions, which uses 
ata_qc_issue/ata_qc_complete high level API to address the device.

In contrast, ata_busy_sleep() sticks its hands deep into the host state 
machine, and gives the tree a good hard shake.  :)  Consider that 
ata_busy_sleep() doesn't make sense for unusual cases like 
ATA-over-ethernet (AoE), or other tunnelled ATA transports.

It may very well be that ata_busy_sleep() is the proper solution for 
your hardware, but it isn't applicable to all hardware.

So you really want an ata_make_sure_bus_is_awake_and_working() called at 
that location.  ata_busy_sleep()'s purpose is to bring a PATA-like bus 
to the bus-idle state.  So, when working on suspend/resume, the software 
needs to have points at which the bus state is controlled/queried/asserted.

	Jeff