From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthias Brugger Subject: Re: [RESEND PATCH v3 1/2] dt-bindings: i2c: Add Mediatek MT2701 i2c binding Date: Tue, 23 May 2017 08:31:53 +0200 Message-ID: References: <1489029185-21447-1-git-send-email-jun.gao@mediatek.com> <1489029185-21447-2-git-send-email-jun.gao@mediatek.com> <20170322090543.sxacnddn2o7stjnq@ninjato> <1490694612.18582.11.camel@mhfsdcap03> <20170328192258.GA4525@katana> <4111ffc2-0a25-0811-fbd3-401649431315@gmail.com> <1495510441.930.7.camel@mhfsdcap03> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail-wm0-f66.google.com ([74.125.82.66]:33729 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757553AbdEWGcA (ORCPT ); Tue, 23 May 2017 02:32:00 -0400 In-Reply-To: <1495510441.930.7.camel@mhfsdcap03> Content-Language: en-US Sender: linux-i2c-owner@vger.kernel.org List-Id: linux-i2c@vger.kernel.org To: Jun Gao , robh@kernel.org Cc: Wolfram Sang , srv_heupstream@mediatek.com, devicetree@vger.kernel.org, linux-i2c@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mediatek@lists.infradead.org, yingjoe.chen@mediatek.com On 23/05/17 05:34, Jun Gao wrote: > On Wed, 2017-05-10 at 12:35 +0200, Matthias Brugger wrote: >> >> On 28/03/17 21:22, Wolfram Sang wrote: >>> On Tue, Mar 28, 2017 at 05:50:12PM +0800, Jun Gao wrote: >>>> On Wed, 2017-03-22 at 10:05 +0100, Wolfram Sang wrote: >>>>> On Thu, Mar 09, 2017 at 11:13:04AM +0800, Jun Gao wrote: >>>>>> From: Jun Gao >>>>>> >>>>>> Add MT2701 i2c binding to i2c-mt6577.txt and there is no need to >>>>>> modify i2c driver. >>>>>> >>>>>> Signed-off-by: Jun Gao >>>>> >>>>> There is still the issue which Matthias Brugger pointed out on January, >>>>> 24th: you need to describe the fallback compatibles. >>>>> >>>> >>>> IMHO the value under compatible are just inputs which can be accepted. >>>> It's little strange to add fallback information in binding. Some other >>>> bindings do not describe so detailedly. >>>> Is it OK to make binding as minimum standard? >>>> If we describe it very detailedly, we will have to modify binding if >>>> there are some changes for mt2701. >>> >>> My reading of the below is that I could simply use "mediatek,mt2701-i2c" >>> as compatible and things will work. But it won't, we don't have that in >>> the driver IIRC. So, we need a fallback for that to work. >>> >>>> Rob, could you give some suggestions? Thanks! >>> >>> Would be welcome, yes. I lost track what the preferred solution is. >>> >> >> We will need to define the fallback binding for each SoC. >> As example take the rockchip mmc: >> http://elixir.free-electrons.com/linux/latest/source/Documentation/devicetree/bindings/mmc/rockchip-dw-mshc.txt >> >> Regards, >> Matthias >> > > Hi Rob, > > There is no such requirement for other components. The requirement is that the binding description reflects a compatible the driver is able to consume. Right now if you pass "mediatek,mt2701-i2c" the driver won't recognize this, therefor you need the fallback compatible. Which point isn't clear to you? Regards, Matthias > Could you give us some suggestions? > Thanks! > > >>>> >>>>>> --- >>>>>> .../devicetree/bindings/i2c/i2c-mt6577.txt | 11 ++++++----- >>>>>> 1 file changed, 6 insertions(+), 5 deletions(-) >>>>>> >>>>>> diff --git a/Documentation/devicetree/bindings/i2c/i2c-mt6577.txt b/Documentation/devicetree/bindings/i2c/i2c-mt6577.txt >>>>>> index 0ce6fa3..27dbbf9 100644 >>>>>> --- a/Documentation/devicetree/bindings/i2c/i2c-mt6577.txt >>>>>> +++ b/Documentation/devicetree/bindings/i2c/i2c-mt6577.txt >>>>>> @@ -4,11 +4,12 @@ The Mediatek's I2C controller is used to interface with I2C devices. >>>>>> >>>>>> Required properties: >>>>>> - compatible: value should be either of the following. >>>>>> - (a) "mediatek,mt6577-i2c", for i2c compatible with mt6577 i2c. >>>>>> - (b) "mediatek,mt6589-i2c", for i2c compatible with mt6589 i2c. >>>>>> - (c) "mediatek,mt8127-i2c", for i2c compatible with mt8127 i2c. >>>>>> - (d) "mediatek,mt8135-i2c", for i2c compatible with mt8135 i2c. >>>>>> - (e) "mediatek,mt8173-i2c", for i2c compatible with mt8173 i2c. >>>>>> + "mediatek,mt2701-i2c" >>>>>> + "mediatek,mt6577-i2c" >>>>>> + "mediatek,mt6589-i2c" >>>>>> + "mediatek,mt8127-i2c" >>>>>> + "mediatek,mt8135-i2c" >>>>>> + "mediatek,mt8173-i2c" >>>>>> - reg: physical base address of the controller and dma base, length of memory >>>>>> mapped region. >>>>>> - interrupts: interrupt number to the cpu. >>>>>> -- >>>>>> 1.7.9.5 >>>>>> >>>> >>>> > >