From: Arnd Bergmann <arnd@arndb.de>
To: "Russell King - ARM Linux" <linux@arm.linux.org.uk>
Subject: Re: [PATCH] OMAP: iommu flush page table entries from L1 and L2 cache
Date: Mon, 18 Apr 2011 09:29:33 +0200
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Cc: Fernando Guzman Lugo <fernando.lugo@ti.com>, linux-omap@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        tony@atomide.com, Ramesh Gupta <grgupta@ti.com>,
        Hari Kanigeri <h-kanigeri2@ti.com>
References: <1302817968-28516-1-git-send-email-fernando.lugo@ti.com> <20110414223036.GA7335@n2100.arm.linux.org.uk>
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On Friday 15 April 2011, Russell King - ARM Linux wrote:
> On Thu, Apr 14, 2011 at 04:52:48PM -0500, Fernando Guzman Lugo wrote:
> > From: Ramesh Gupta <grgupta@ti.com>
> > 
> > This patch is to flush the iommu page table entries from L1 and L2
> > caches using dma_map_single. This also simplifies the implementation
> > by removing the functions  flush_iopgd_range/flush_iopte_range.
> 
> No.  This usage is just wrong.  If you're going to use the DMA API then
> unmap it, otherwise the DMA API debugging will go awol.


It's also completely upside-down: The iommu support should provide interfaces
using the dma-mapping API, not use that API to provide a machine specific
version of the generic interface.

As far as I can tell, nothing actually uses these drivers, maybe we should just
remove them before we get any code in the mainline kernel that depends on it.

	Arnd
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