From: Scott Wood <scottwood@freescale.com>
To: Bogdan Purcareata <bogdan.purcareata@freescale.com>
Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] powerpc/mpic: Add DT option to skip readback after EOI
Date: Wed, 14 Jan 2015 11:58:32 -0600 [thread overview]
Message-ID: <1421258312.4961.133.camel@freescale.com> (raw)
In-Reply-To: <1421236622-29366-1-git-send-email-bogdan.purcareata@freescale.com>
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
WARNING: multiple messages have this Message-ID (diff)
From: Scott Wood <scottwood@freescale.com>
To: Bogdan Purcareata <bogdan.purcareata@freescale.com>
Cc: <benh@kernel.crashing.org>, <linuxppc-dev@lists.ozlabs.org>,
<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] powerpc/mpic: Add DT option to skip readback after EOI
Date: Wed, 14 Jan 2015 11:58:32 -0600 [thread overview]
Message-ID: <1421258312.4961.133.camel@freescale.com> (raw)
In-Reply-To: <1421236622-29366-1-git-send-email-bogdan.purcareata@freescale.com>
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
next prev parent reply other threads:[~2015-01-14 17:58 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-14 11:57 [PATCH] powerpc/mpic: Add DT option to skip readback after EOI Bogdan Purcareata
2015-01-14 11:57 ` Bogdan Purcareata
2015-01-14 17:58 ` Scott Wood [this message]
2015-01-14 17:58 ` Scott Wood
2015-01-21 9:35 ` Purcareata Bogdan
2015-01-21 9:35 ` Purcareata Bogdan
2015-01-21 9:49 ` Scott Wood
2015-01-21 9:49 ` Scott Wood
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