From mboxrd@z Thu Jan 1 00:00:00 1970 From: Laurent Pinchart Subject: Re: [RFC/PATCH 02/13] media: s5p-csis: Add device tree support Date: Tue, 31 Jul 2012 13:05:23 +0200 Message-ID: <4835930.8zRiqxUPR0@avalon> References: <4FBFE1EC.9060209@samsung.com> <24452426.AaRH9zzLOy@avalon> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org Sender: "devicetree-discuss" To: Guennadi Liakhovetski Cc: linux-samsung-soc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, b.zolnierkie-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org, riverful.kim-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org, devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org, sw0312.kim-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org, kyungmin.park-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org, Sylwester Nawrocki , Sylwester Nawrocki , linux-media-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, m.szyprowski-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org List-Id: devicetree@vger.kernel.org Hi Guennadi, On Tuesday 31 July 2012 12:58:50 Guennadi Liakhovetski wrote: > On Fri, 27 Jul 2012, Laurent Pinchart wrote: > > On Thursday 26 July 2012 21:51:30 Sylwester Nawrocki wrote: > > > On 07/26/2012 04:38 PM, Laurent Pinchart wrote: > > > >>>> --- /dev/null > > > >>>> +++ b/Documentation/devicetree/bindings/video/mipi.txt > > > >>>> @@ -0,0 +1,5 @@ > > > >>>> +Common properties of MIPI-CSI1 and MIPI-CSI2 receivers and > > > >>>> transmitters > > > >>>> + > > > >>>> + - data-lanes : number of differential data lanes wired and > > > >>>> actively > > > >>>> used in > > > >>>> + communication between the transmitter and the receiver, this > > > >>>> + excludes the clock lane; > > > >>> > > > >>> Wouldn't it be better to use the standard "bus-width" DT property? > > > >> > > > >> I can't see any problems with using "bus-width". It seems sufficient > > > >> and could indeed be better, without a need to invent new MIPI-CSI > > > >> specific names. That was my first RFC on that and my perspective > > > >> wasn't probably broad enough. :) > > > > > > > > What about CSI receivers that can reroute the lanes internally ? We > > > > would > > > > need to specify lane indices for each lane then, maybe with something > > > > like > > > > > > > > clock-lane =<0>; > > > > data-lanes =<2 3 1>; > > > > > > Sounds good to me. And the clock-lane could be made optional, as not all > > > devices would need it. > > > > > > However, as far as I can see, there is currently no generic API for > > > handling this kind of data structure. E.g. number of cells for the > > > "interrupts" property is specified with an additional > > > "#interrupt-cells" property. > > > > > > It would have been much easier to handle something like: > > > > > > data-lanes = <2>, <3>, <1>; > > > > > > i.e. an array of the lane indexes. > > > > I'm fine with that. > > ...on a second thought: shouldn't this be handled by pinctrl? Or is it > some CSI-2 module internal lane switching, not the global SoC pin function > configuration? On the hardware I came across, it's handled by the CSI2 receiver, not the SoC pinmux feature. -- Regards, Laurent Pinchart