linux-kernel - Re: [PATCH] OMAP: iommu flush page table entries from L1 and L2 cache

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Message-ID: <BANLkTin8gugnVoai6VHC7qMgK4eKRXRtHg@mail.gmail.com>
Date:	Fri, 15 Apr 2011 06:26:40 -0500
From:	"Gupta, Ramesh" <grgupta@...com>
To:	Russell King - ARM Linux <linux@....linux.org.uk>
Cc:	Fernando Guzman Lugo <fernando.lugo@...com>,
	linux-omap@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org, tony@...mide.com,
	Hari Kanigeri <h-kanigeri2@...com>
Subject: Re: [PATCH] OMAP: iommu flush page table entries from L1 and L2 cache

Russell,

On Thu, Apr 14, 2011 at 5:30 PM, Russell King - ARM Linux
<linux@....linux.org.uk> wrote:
> On Thu, Apr 14, 2011 at 04:52:48PM -0500, Fernando Guzman Lugo wrote:
>> From: Ramesh Gupta <grgupta@...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.
>

Thank you for the comments, this particular memory is always a write
from the A9 for MMU programming and
only read from the slave processor, that is the reason for not calling
the unmap. I can re-look into the changes to call
unmap in a proper way as this impacts the DMA API.
Are there any other ways to perform only flush the memory from L1/L2 caches?

 regards
Ramesh Gupta G
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