Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Fri, 20 Apr 2018 22:01:34 +0200
From:   Boris Brezillon <boris.brezillon@bootlin.com>
To:     Ladislav Michl <ladis@linux-mips.org>
Cc:     linux-kernel@vger.kernel.org, linux-mtd@lists.infradead.org,
        Boris Brezillon <boris.brezillon@free-electrons.com>,
        Peter Ujfalusi <peter.ujfalusi@ti.com>,
        Roger Quadros <rogerq@ti.com>,
        Aaro Koskinen <aaro.koskinen@iki.fi>,
        Tony Lindgren <tony@atomide.com>,
        "H. Nikolaus Schaller" <hns@goldelico.com>,
        Andreas Kemnade <andreas@kemnade.info>
Subject: Re: [PATCH v2] mtd: onenand: omap2: Disable DMA for HIGHMEM buffers
Message-ID: <20180420220134.3021860f@bbrezillon>
In-Reply-To: <20180416065256.GA24455@lenoch>
References: <20180416065256.GA24455@lenoch>
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Hi Ladislav,

On Mon, 16 Apr 2018 08:52:59 +0200
Ladislav Michl <ladis@linux-mips.org> wrote:

> dma_map_single doesn't get the proper DMA address for vmalloced area,

That's not true, it returns the right DMA (physical) address, it's just
that:

1/ the memory location is not necessarily physically contiguous
2/ in case your arch is VIVT ot VIPT, there may be several entries in
   the cache pointing to the same physical location, and the cache
   maintenance operations done by dma_map_single() will only operate on
   one of these entries.

> so disable DMA in this case.
> 

The fix looks good though. Can you rephrase your commit message to make
it clearer.

Thanks,

Boris