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Message-ID: <4B6FE162.6000004@warmcat.com>
Date: Mon, 08 Feb 2010 11:03:14 +0100
From: Andy Green <andy@...mcat.com>
To: Catalin Marinas <catalin.marinas@....com>
CC: Pavel Machek <pavel@....cz>,
Matthew Dharm <mdharm-kernel@...-eyed-alien.net>,
Sergei Shtylyov <sshtylyov@...mvista.com>,
Ming Lei <tom.leiming@...il.com>,
Sebastian Siewior <bigeasy@...utronix.de>,
linux-usb@...r.kernel.org,
linux-kernel <linux-kernel@...r.kernel.org>,
Greg KH <greg@...ah.com>,
linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>
Subject: Re: USB mass storage and ARM cache coherency
On 02/08/10 10:51, Somebody in the thread at some point said:
> We could of course flush the caches every time we get a page fault but
> that's far from optimal, especially since DMA-capable drivers to do not
> pollute the D-cache and don't need this extra flushing. Note that the
> recent ARM processors have PIPT caches but separate for I and D and it's
> the PIO drivers that pollute the D-cache.
Just noting that AFAIK iMX31 USB and MMC drivers both are PIO at the
moment, for lack of any platform DMA support of its unusual DMA engine.
-Andy
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