Re: Hot add a PCIe device driver upon hotplug event

[Ludwig Petrosyan <ludwig.petrosyan@desy.de>]

Hi Bjorn

yes this that are refer, more detailed version was in previous Workshop
https://indico.desy.de/getFile.py/access?contribId=5&sessionId=1&resId=0&materialId=slides&confId=7866
and additionally was presentation about driver part
https://indico.desy.de/getFile.py/access?contribId=32&sessionId=9&resId=0&materialId=slides&confId=10329

I hope this will help and may be I will get some feedback to improve
both and fix bugs

Cheers

Ludwig

On 01/27/2015 05:50 PM, Bjorn Helgaas wrote:
> Hi Ludwig,
>
> Thanks a lot for the pointers to MTCA information.  I found
> presentation slides here:
> https://indico.desy.de/getFile.py/access?contribId=33&sessionId=0&resId=1&materialId=slides&confId=10329,
> which I assume is that you're referring to.
>
> On Mon, Jan 26, 2015 at 1:38 AM, Ludwig Petrosyan
> <ludwig.petrosyan@desy.de> wrote:
>> Hello
>>
>> (I have send this email two days ago but got status undeliverable, so try to
>> send it again)
>>
>> We had the same problem on the MTCA system years ago, but now the problem is
>> solved.
>> The MTCA system is a kind of ATCA and I think attention Button problem could
>> be solved in the same way.
>> Ok, now what we have done:
>> First of all the main difference of the ATCA or MTCA PCIe system is what the
>> PCIe Switch which responsible for the HotPlug
>>
>> (I mean Switch which is connected to the crate slots, and hotplug
>> controllers of this are used in hotpluging ) and the Attention Button of the
>>
>> PCIe slot reside on the different boards (usually PCIe Switch is on the
>> Crate Manager  board and Attention Button is  the AMC module Latch ),
>>
>> So there are no any wired connections between Attention Button and PCIe
>> Switch. Than user pool out the AMC module Latch the PCIe Switch has no idea
>>
>> about that, BUT the AMC module controller (MMC) sends IPMI message to the
>> Crate Management Controller (MCMC)
>> and MCMC starts AMC powering down procedures. The idea was: usually MCMC and
>> PCIe Switch reside on the same board and MCMC getting IPMI message
>>
>> about state change of the AMC Latch (latch polled out or pressed) set
>> appropriate registers of the PCIe Switch or push high appropriate lines of
>> the PCIe Switch
>>
>> and PCIe Switch gets information that Attention Button is pressed and send
>> hotplug interrupt to the hotplug driver.
>> This approach works in our MTCA systems and we have a full working PCIe
>> HotPlug.
> It sounds like you basically have some IPMI glue between the the AMC
> latch and the PCIe Attention Button, and from the point of view of the
> pciehp (PCIe native hotplug) driver, it just sees a normal Attention
> Button.  That sounds like a reasonable thing to do.
>
> In Paulo's case, it sounds like there is some sort of switch related
> to the card, but the IPMI or similar glue that could potentially lead
> to the Attention Button line doesn't exist.  In that case, pciehp
> doesn't know anything about the switch.  If there's some other way,
> e.g., IPMI, to learn about the switch, maybe that could be done via a
> separate driver.
>
>> More detailed information one can get to look documents of the MTCA Workshop
>> (http://mtcaws.desy.de/) in tutorial section was presentation about
>>
>> PCIe Hotplug, or look in PICMIG recommendation (there is new recommendation
>> about PCIe HotPlug for MTC.4)
>>
>> With best regards
>>
>> Ludwig Petrosyan
>>
>>