Adding port multiplier support to a LLDD

Adding port multiplier support to a LLDD

[Mark Miesfeld]

Hi,

I wonder if someone could give me a broad outline of what is needed to
add port multiplier support to a low-level SATA device driver through
libata in a 2.6.26 kernel.

I'm working on a driver for a new SOC (460EX) that AMCC has.  The chip
has support for SATA and support for port multipliers through
command-based switching.

For our in-house validation boards I have the driver working on a
2.6.19 kernel and implemented the port multiplier support within the
driver itself since libata didn't yet have port multiplier support.

Our customer evaluation boards (Canyonlands) are using a 2.6.26
kernel.  Stefan Roese at DENX has ported the 2.6.19 driver to 2.6.26
but without port multiplier support.  In 2.6.26 the libata port
multiplier support looks pretty good, I was hoping I can add the
support to the 2.6.26 driver fairly easily by going through libata.

What basic steps should I take?

Thanks.

--
Mark Miesfeld

Re: Adding port multiplier support to a LLDD

[Tejun Heo]

Mark Miesfeld wrote:
> Hi,
> 
> I wonder if someone could give me a broad outline of what is needed to
> add port multiplier support to a low-level SATA device driver through
> libata in a 2.6.26 kernel.
> 
> I'm working on a driver for a new SOC (460EX) that AMCC has.  The chip
> has support for SATA and support for port multipliers through
> command-based switching.
> 
> For our in-house validation boards I have the driver working on a
> 2.6.19 kernel and implemented the port multiplier support within the
> driver itself since libata didn't yet have port multiplier support.
> 
> Our customer evaluation boards (Canyonlands) are using a 2.6.26
> kernel.  Stefan Roese at DENX has ported the 2.6.19 driver to 2.6.26
> but without port multiplier support.  In 2.6.26 the libata port
> multiplier support looks pretty good, I was hoping I can add the
> support to the 2.6.26 driver fairly easily by going through libata.
> 
> What basic steps should I take?

The following thread should help.

http://thread.gmane.org/gmane.linux.ide/24799

-- 
tejun