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Subject: Re: [PATCH] powerpc/mpic: Add DT option to skip readback after EOI
From: Scott Wood <scottwood@freescale.com>
To: Bogdan Purcareata <bogdan.purcareata@freescale.com>
Date: Wed, 14 Jan 2015 11:58:32 -0600
In-Reply-To: <1421236622-29366-1-git-send-email-bogdan.purcareata@freescale.com>
References: <1421236622-29366-1-git-send-email-bogdan.purcareata@freescale.com>
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On Wed, 2015-01-14 at 11:57 +0000, Bogdan Purcareata wrote:
> The readback is necessary in order to handle PCI posted
> writes,

That is unclear.

>  or when the MPIC is handling interrupts in a loop
> (ppc_md.get_irq).

I'm questioning this one as well -- if reading WHOAMI is sufficient to
sync with the EOI, why wouldn't reading INTACK work as well?

>  Newer MPIC versions don't require this readback. Leave the option
> configurable using a device tree entry.
> 
> This saves a MMIO trap per interrupt.
> 
> Signed-off-by: Scott Wood <scottwood@freescale.com>
> Signed-off-by: Bogdan Purcareata <bogdan.purcareata@freescale.com>

You should note changes (e.g. with a [] note between signoffs) if it
differs from the original...

-Scott