Does ICH9M support eSATA Port Multiplier?

Does ICH9M support eSATA Port Multiplier?

[Peter Klotz]

I have the following setup:

Notebook (Ubuntu 9.10, 2.6.31-14 amd64) with ICH9M controller in AHCI 
mode and an external storage box (Sil5744, 2 HDDs) connected via eSATA.

The box supports JBOD and the manufacturer says that a Port Multiplier 
capable eSATA port is needed to see both HDDs.

I see only one HDD.

Here is part of the dmesg output from startup:

[    0.725096] ahci 0000:00:1f.2: AHCI 0001.0200 32 slots 4 ports 3 Gbps 
0x23 impl SATA mode
[    0.725099] ahci 0000:00:1f.2: flags: 64bit ncq sntf stag pm led clo 
pio slum part ems


The pmp flag is not present but several sources claim that ICH9 supports 
Port Multiplier.

Should Port Multiplier be available for ICH9M?
Can I enable it somehow maybe by using a module option?

Regards, Peter.

Re: Does ICH9M support eSATA Port Multiplier?

[Robert Hancock]

On 10/29/2009 01:36 PM, Peter Klotz wrote:
> I have the following setup:
>
> Notebook (Ubuntu 9.10, 2.6.31-14 amd64) with ICH9M controller in AHCI
> mode and an external storage box (Sil5744, 2 HDDs) connected via eSATA.
>
> The box supports JBOD and the manufacturer says that a Port Multiplier
> capable eSATA port is needed to see both HDDs.
>
> I see only one HDD.
>
> Here is part of the dmesg output from startup:
>
> [ 0.725096] ahci 0000:00:1f.2: AHCI 0001.0200 32 slots 4 ports 3 Gbps
> 0x23 impl SATA mode
> [ 0.725099] ahci 0000:00:1f.2: flags: 64bit ncq sntf stag pm led clo pio
> slum part ems
>
>
> The pmp flag is not present but several sources claim that ICH9 supports
> Port Multiplier.

It seems like it may be variable between specific ICH versions (mobile, 
RAID, etc.) whether they support PMP or not. Obviously in your case the 
controller doesn't report PMP support in the AHCI capabilities register.

>
> Should Port Multiplier be available for ICH9M?
> Can I enable it somehow maybe by using a module option?

No module parameter for that, you'd have to hack the code in ahci.c to 
force the option on. No guarantees it's going to work if the controller 
doesn't report the capability, though.

Re: Does ICH9M support eSATA Port Multiplier?

[Peter Klotz]

Robert Hancock wrote:
>> Can I enable it somehow maybe by using a module option?
> 
> No module parameter for that, you'd have to hack the code in ahci.c to 
> force the option on. No guarantees it's going to work if the controller 
> doesn't report the capability, though.

Could you please give me a hint what to change in ahci.c?

I would like to try and see what happens.

Could such a hack damage the hardware?

Regards, Peter.

Re: Does ICH9M support eSATA Port Multiplier?

[Robert Hancock]

On 10/30/2009 04:10 PM, Peter Klotz wrote:
> Robert Hancock wrote:
>>> Can I enable it somehow maybe by using a module option?
>>
>> No module parameter for that, you'd have to hack the code in ahci.c to
>> force the option on. No guarantees it's going to work if the
>> controller doesn't report the capability, though.
>
> Could you please give me a hint what to change in ahci.c?
>
> I would like to try and see what happens.

Based on the version in Linus' git, you'd likely want to add to 
ahci_save_initial_config something like:

cap |= HOST_CAP_PMP;

>
> Could such a hack damage the hardware?

Not likely. It's not impossible that data loss could result though, 
better back up important files first..

Re: Does ICH9M support eSATA Port Multiplier?

[Peter Klotz]

Robert Hancock wrote:
> On 10/30/2009 04:10 PM, Peter Klotz wrote:
>> Robert Hancock wrote:
>>>> Can I enable it somehow maybe by using a module option?
>>>
>>> No module parameter for that, you'd have to hack the code in ahci.c to
>>> force the option on. No guarantees it's going to work if the
>>> controller doesn't report the capability, though.
>>
>> Could you please give me a hint what to change in ahci.c?
>>
>> I would like to try and see what happens.
> 
> Based on the version in Linus' git, you'd likely want to add to 
> ahci_save_initial_config something like:
> 
> cap |= HOST_CAP_PMP;
> 
>>
>> Could such a hack damage the hardware?
> 
> Not likely. It's not impossible that data loss could result though, 
> better back up important files first..

Thanks a lot. I had already prepared the kernel, then I found the Intel 
datasheet, which states that ICH9 does not support port multipliers.

http://www.intel.com/assets/pdf/datasheet/316972.pdf

Regards, Peter.