Re: [PATCH] libata: add enclosure management support

[Kristen Carlson Accardi <kristen.c.accardi@intel.com>]

On Thu, 17 Jan 2008 16:50:42 -0600
James Bottomley <James.Bottomley@HansenPartnership.com> wrote:

> On Tue, 2008-01-15 at 16:44 -0800, Kristen Carlson Accardi wrote:
> > Add Enclosure Management support to libata and ahci.
> > 
> > This patch adds support for the LED protocol, as defined in the
> > AHCI spec. It adds a generic em_message and em_type sysfs entry per
> > host.  It also adds a sw_activity field per existing drive.
> > 
> > The em_message field can be used by the driver to take enclosure
> > management commands from userspace.  In the case of the LED
> > protocol, writes and reads from em_message correspond to the LED
> > message format as defined in the AHCI spec.
> > 
> > em_message type is a read only file that displays the current
> > enclosure management protocol that is used by the driver.
> > 
> > sw_activity is used by drivers which support software controlled
> > activity LEDs. It has the following valid values:
> > 
> > 0	OFF - the LED is not activated on activity
> > 1	BLINK_ON - the LED blinks on every 10ms when activity is
> > detected. 2	BLINK_OFF - the LED is on when idle, and blinks
> > off every 10ms when activity is detected.
> > 
> > It's important to note that the user must turn sw_activity OFF it
> > they wish to control the activity LED via the em_message file.
> 
> One of the things we really need to do is to get some type of generic
> enclosure support.  I note that ahci support three standard eclosure
> management protocols (SAF-TE, SES-2, SFF-8485 SGPIO) as well as the
> one proprietary one you've chosen to implement.  Is that because
> no-one in the field has actually connected AHCI up to anything
> supporting one of the standard protocols?

Correct - I've not seen any AHCI hardware that supports anything but
the LED protocol so far.