Re: [PATCH 10/11] ARM: dts: qcom: Update devicetree for QCOM ADC bindings path change

From: Bjorn Andersson <quic_bjorande@quicinc.com>
To: Jishnu Prakash <quic_jprakash@quicinc.com>
Cc: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
	<agross@kernel.org>, <devicetree@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>, <linus.walleij@linaro.org>,
	<Jonathan.Cameron@huawei.com>, <sboyd@kernel.org>,
	<dmitry.baryshkov@linaro.org>, <quic_subbaram@quicinc.com>,
	<quic_collinsd@quicinc.com>, <quic_kamalw@quicinc.com>,
	<marijn.suijten@somainline.org>,
	<andriy.shevchenko@linux.intel.com>,
	Bjorn Andersson <andersson@kernel.org>,
	Konrad Dybcio <konrad.dybcio@linaro.org>,
	Rob Herring <robh+dt@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Conor Dooley <conor+dt@kernel.org>,
	<cros-qcom-dts-watchers@chromium.org>,
	<linux-arm-msm@vger.kernel.org>, <linux-iio@vger.kernel.org>,
	<linux-arm-msm-owner@vger.kernel.org>
Subject: Re: [PATCH 10/11] ARM: dts: qcom: Update devicetree for QCOM ADC bindings path change
Date: Fri, 10 Nov 2023 15:47:58 -0800	[thread overview]
Message-ID: <20231110234758.GE3553829@hu-bjorande-lv.qualcomm.com> (raw)
In-Reply-To: <706d3b7e-a9b5-081c-52b2-7cce4f0d5f10@quicinc.com>

On Mon, Oct 23, 2023 at 11:48:13AM +0530, Jishnu Prakash wrote:
> Hi Krzysztof,
> 
> On 7/9/2023 10:56 PM, Krzysztof Kozlowski wrote:
> > On 08/07/2023 09:28, Jishnu Prakash wrote:
> > > Update ADC dt-bindings file paths in QCOM devicetree files to
> > > match the dt-bindings change moving the files from 'iio' to
> > > 'iio/adc' folder.
> > > 
> > > Signed-off-by: Jishnu Prakash <quic_jprakash@quicinc.com>
> > > ---
> > Your order of patches is incorrect. DTS cannot be before bindings,
> > because this indicates you broke ABI. Please keep entire patchset
> > bisectable and split DTS to separate patchset (linking the driver and
> > bindings).
> > 
> > Best regards,
> > Krzysztof
> 
> OK....so you mean I can move the dtbinding files and update documentation
> and driver files for this, all in one patch and then make a second patch for
> updating devicetree files for the file paths?
> 
> I'll make this change in the next patchset if it looks fine, although the
> two patches would need to be picked together to avoid kernel breakage. I
> have asked Jonathan about this too in my reply for the previous patchset 9.
> 

1) We need to be able to use git bisect to identify regressions, and as
such the kernel need to be buildable and functional after each applied
patch.

2) DeviceTree source (dts) changes enters the kernel through different
maintainer paths than the DeviceTree binding and driver changes, and
therefore at different times. In some cases the .dtb file is also
delivered separately from the kernel, which means people might be
running an old .dtb for a considerable amount of time after your change.
As such your driver changes needs to be compatible with both the new and
the old DeviceTree binding.

Regards,
Bjorn