From mboxrd@z Thu Jan  1 00:00:00 1970
From: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Date: Thu, 02 Aug 2007 14:04:42 +0000
Subject: Re: [RFC][PATCH 0/2] SN platform needs platform_irq_to_vector?
Message-Id: <1186063482.6282.64.camel@kane-linux>
List-Id: <linux-ia64.vger.kernel.org>
References: <1186028871.3875.12.camel@kane-linux>
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To: linux-ia64@vger.kernel.org

Hi,

This is FYI.

If VECTOR_DOMAIN_PERCPU is NOT enabled:

The "irq = vector" is always true in the following cases:
    - reserve_irq_vector(), which is used only by SN
    - create_irq() used on the system that has NO I/O SAPIC
    - assign_irq_vector() with AUTO_ASSIGN specified
    - Vectors outside FIRST_DEVICE_VECTOR to LAST_DEVICE_VECTOR

The "irq = vector" is not always true in the folliwng cases:
    - create_irq() used on the system that has I/O SAPICs.
    - assign_irq_vector() with the value other than AUTO_ASSIGN
      specified on the system has I/O SAPICs.

And it is not ensured that those are true even in the future.

Yasuaki, could you check if it is correct?

Thanks,
Kenji Kaneshige



2007-08-02 (木) の 08:26 -0500 に John Keller さんは書きました:
> Yes, we'll take a look at it.
> 
> John
> 
> 
> > 
> > Hi Kenji-san
> > 
> > I believe we need this property, but I am not 100% sure, so I am
> > going to forward your patch to our team who maintain the IRQ code
> > for Altix.
> > 
> > Mike, Aaron or John, would one of you have time to take a look at
> > this?
> > 
> > Thanks,
> > Jes
> > 
> > 
> > Kenji Kaneshige wrote:
> > > Hi Jes-san, Russ-san, Christoph-san and SN platform developers,
> > > 
> > > I glanced over the SN code, and I found SN platform doesn't have SN
> > > specific irq_to_vector() function, though it has SN specific
> > > local_vector_to_irq() function. I guess it was OK because maybe SN
> > > platform depends on irq = vector and old generic irq_to_vector() was
> > > just returning the same value as irq.
> > > 
> > > The irq_to_vector() function, however, has been changed by vector
> > > domain support, and currently it can return the different value from
> > > irq, even when VECTOR_DOMAIN_PERCPU is not enabled. This can happen
> > > when an interrupt thorough I/O SAPIC is unregistered and another
> > > interupt is registered. So if my guess (SN platform depends on irq =
> > > vector) is true, something problem might happen on SN platform when
> > > PCI hotplugging or driver reloading.
> > > 
> > > If it is true that SN platform depends on irq = vector, we need to
> > > implement SN specific irq_to_vector() that returns the same value as
> > > irq, I think. I made sample patches to implement platform specific
> > > irq_to_vector() as follows. Note that [PATCH 2/2] is not tested yet
> > > because I don't have any SN platform unfortunately.
> > > 
> > >     [PATCH 1/2] Add base support for platform_irq_to_vector()
> > >     [PATCH 2/2] Implement platform_irq_to_vector() for SN
> > > 
> > > Could you give me comments?
> > > 
> > > Thanks,
> > > Kenji Kaneshige
> > > 
> > 
> > 
> 
> -
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