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From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: michael@ellerman.id.au
Cc: linuxppc-dev@ozlabs.org
Subject: Re: [PATCH 3/4] Simplify rtas_change_msi() error semantics
Date: Tue, 02 Oct 2007 16:24:13 +1000	[thread overview]
Message-ID: <1191306253.6310.106.camel@pasglop> (raw)
In-Reply-To: <1191304690.6593.8.camel@concordia>


On Tue, 2007-10-02 at 15:58 +1000, Michael Ellerman wrote:
> > Looks allright, just a question tho... what do we do if it fails ?
> Do we
> > try to fallback to a lower number of MSIs ? Or what ? Dead device ?
> 
> That's all up to the device driver. In theory the driver could try again
> with a lower count - but that might require extra logic in the driver to
> handle shared irq handlers etc. In practice I think the current drivers
> will just fail.

Question is badly phrased.. I meant something more like... what do we do
if RTAS returns a lower count ?

That is, we end up with that device with that lower count of MSIs
enabled, we fail at the driver level, do we still somewhat keep track ?
Drivers might assume that means it can use LSIs no ? which may not be
the case... Shouldn't we try to switch back to LSI mode (or does the
RTAS interface doesnt allow it ?)

Ben.

  reply	other threads:[~2007-10-02  6:24 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-09-20  6:36 [PATCH 1/4] Simplify error logic in u3msi_setup_msi_irqs() Michael Ellerman
2007-09-20  6:36 ` [PATCH 2/4] Simplify error logic in rtas_setup_msi_irqs() Michael Ellerman
2007-10-02  5:21   ` Benjamin Herrenschmidt
2007-09-20  6:36 ` [PATCH 3/4] Simplify rtas_change_msi() error semantics Michael Ellerman
2007-10-02  5:23   ` Benjamin Herrenschmidt
2007-10-02  5:58     ` Michael Ellerman
2007-10-02  6:24       ` Benjamin Herrenschmidt [this message]
2007-10-02  7:40         ` Michael Ellerman
2007-10-02  8:37           ` Benjamin Herrenschmidt
2007-09-20  6:36 ` [PATCH 4/4] Inline u3msi_compose_msi_msg() Michael Ellerman
2007-10-02  5:24   ` Benjamin Herrenschmidt
2007-10-02  5:21 ` [PATCH 1/4] Simplify error logic in u3msi_setup_msi_irqs() Benjamin Herrenschmidt

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