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[24.6.192.50]) by smtp.gmail.com with ESMTPSA id 11sm5738096pfu.155.2019.05.24.17.25.26 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 24 May 2019 17:25:27 -0700 (PDT) Subject: Re: [PATCH v1 0/5] Solve postboot supplier cleanup and optimize probe ordering From: Frank Rowand To: Saravana Kannan Cc: Rob Herring , Mark Rutland , Greg Kroah-Hartman , "Rafael J. Wysocki" , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Android Kernel Team References: <20190524010117.225219-1-saravanak@google.com> <06b479e2-e8a0-b3e8-567c-7fa0f1c5bdf6@gmail.com> <6d3995c1-e1e7-35ff-d091-501822c97ecd@gmail.com> Message-ID: <0634ea45-2941-73fb-f8d8-b536e929a4a8@gmail.com> Date: Fri, 24 May 2019 17:25:26 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <6d3995c1-e1e7-35ff-d091-501822c97ecd@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/24/19 5:22 PM, Frank Rowand wrote: > On 5/24/19 2:53 PM, Saravana Kannan wrote: >> On Fri, May 24, 2019 at 10:49 AM Frank Rowand wrote: >>> >>> On 5/23/19 6:01 PM, Saravana Kannan wrote: > > < snip > > >>> Another flaw with this method is that existing device trees >>> will be broken after the kernel is modified, because existing >>> device trees do not have the depends-on property. This breaks >>> the devicetree compatibility rules. >> >> This is 100% not true with the current implementation. I actually >> tested this. This is fully backwards compatible. That's another reason >> for adding depends-on and going by just what it says. The existing >> bindings were never meant to describe only mandatory dependencies. So >> using them as such is what would break backwards compatibility. > > Are you saying that an existing, already compiled, devicetree (an FDT) > can be used to boot a new kernel that has implemented this patch set? > > The new kernel will boot with the existing FDT that does not have > any depends-on properties? I overlooked something you said in the email I replied to. You said: "that depends-on becomes the source of truth if it exists and falls back to existing common bindings if "depends-on" isn't present" Let me go back to look at the patch series to see how it falls back to the existing bindings. > > -Frank >