Re: [PATCH] ata: ahci: power off unused ports

From: Mark Lord
Date: Mon Jun 02 2008 - 09:03:20 EST


Jeff Garzik wrote:
Alan Cox wrote:
If you are talking about SATA -- incorrect.

The patch deals with policy, and the user MUST have the ability to control this stuff. Otherwise you create a situation where the user might be denied hotplug use in valid cases, or similar negative situations.

The policy isn't however complicated. Tejun added the stuff for forcing
cable type and mode on setup and has therefore written all the per device
setup code we might need. Alternatively a single

foo=1/0

option has been fine for acpi and will do fine for this. Total additional
cost - 1 line.

The key requirement is per-port control. Ideally via hdparm or another userspace tool, but kernel command line (module options) or sysfs would be just fine too. And agreed, the minimal you need is simply 1/0 for the port's policy.
..

Btw.. hdparm-8.7 (unreleased) can grok /sys now, so that interface is
as good as any from a userspace viewpoint now.

For the power-off of unused ports, the current patch still sounds
extremely vendor-specific (Intel).

Does it actually work (demonstrate, please) on any other hardware ?

I would still like to see a far more generic solution, with periodic polling
and the like, which would permit use on *any* machines (eg. data centers)
without loss of hotplug capability on those ports.

But that's probably just wishful thinking at this point.

Cheers
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/