From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vinod Koul Subject: Re: [PATCH v2 1/2] dmaengine: dma_slave_config: add support for slave port window Date: Tue, 29 Nov 2016 18:44:44 +0530 Message-ID: <20161129131444.GR6408@localhost> References: <20161117125017.14954-1-peter.ujfalusi@ti.com> <20161117125017.14954-2-peter.ujfalusi@ti.com> <1c9221e8-c2e9-4d87-4d74-670e1bc2fec1@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1c9221e8-c2e9-4d87-4d74-670e1bc2fec1@ti.com> Sender: linux-kernel-owner@vger.kernel.org To: Peter Ujfalusi Cc: dan.j.williams@intel.com, tony@atomide.com, linux@armlinux.org.uk, dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org, arnd@arndb.de List-Id: linux-omap@vger.kernel.org On Tue, Nov 29, 2016 at 12:47:48PM +0200, Peter Ujfalusi wrote: > Vinod, > > On 11/17/2016 02:50 PM, Peter Ujfalusi wrote: > > Some slave devices uses address window instead of single register for read > > and/or write of data. With the src/dst_port_window_size the address window > > can be specified and the DMAengine driver should use this information to > > correctly set up the transfer to loop within the provided window. > > > > Signed-off-by: Peter Ujfalusi > > --- > > include/linux/dmaengine.h | 8 ++++++++ > > 1 file changed, 8 insertions(+) > > > > diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h > > index cc535a478bae..689d44327ef3 100644 > > --- a/include/linux/dmaengine.h > > +++ b/include/linux/dmaengine.h > > @@ -336,6 +336,12 @@ enum dma_slave_buswidth { > > * may or may not be applicable on memory sources. > > * @dst_maxburst: same as src_maxburst but for destination target > > * mutatis mutandis. > > + * @src_port_window_size: The length of the register area the data need to be > > + * written on the device side. It is only used for devices which is using an > > + * area instead of a single register to receive the data. Typically the DMA > > + * loops in this area in order to transfer the data. > > + * @dst_port_window_size: same as src_port_window_size but for the destination > > + * port. > > I think this needs some clarification. > Should the src/dst_port_window_size be in bytes or in words? I think it would > make more sense to define it as number of words to be in sync with the > src/dst_maxburst. Yes good catch, I would indeed prefer words here -- ~Vinod