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[95.121.88.74]) by smtp.gmail.com with ESMTPSA id j33sm3629702wre.91.2018.12.18.00.37.30 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 18 Dec 2018 00:37:31 -0800 (PST) Subject: Re: [PATCH 05/13] clk: qcom: apcs-msm8916: get parent clock names from DT To: Stephen Boyd , andy.gross@linaro.org, david.brown@linaro.org, jassisinghbrar@gmail.com, mark.rutland@arm.com, mturquette@baylibre.com, robh+dt@kernel.org, will.deacon@arm.com Cc: bjorn.andersson@linaro.org, vkoul@kernel.org, niklas.cassel@linaro.org, sibis@codeaurora.org, georgi.djakov@linaro.org, arnd@arndb.de, horms+renesas@verge.net.au, heiko@sntech.de, enric.balletbo@collabora.com, jagan@amarulasolutions.com, olof@lixom.net, amit.kucheria@linaro.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, "linux-arm-kernel@lists.infradead.org" , linux-clk@vger.kernel.org References: <1545039990-19984-1-git-send-email-jorge.ramirez-ortiz@linaro.org> <1545039990-19984-6-git-send-email-jorge.ramirez-ortiz@linaro.org> <154508986359.19322.1555129141976726505@swboyd.mtv.corp.google.com> From: Jorge Ramirez Message-ID: <57ef23b0-9c6b-cdd4-9a1a-41c6d5b3aa93@linaro.org> Date: Tue, 18 Dec 2018 09:37:29 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <154508986359.19322.1555129141976726505@swboyd.mtv.corp.google.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/18/18 00:37, Stephen Boyd wrote: > Quoting Jorge Ramirez-Ortiz (2018-12-17 01:46:22) >> Allow accessing the parent clock names required for the driver >> operation by using the device tree node. >> >> This permits extending the driver to other platforms without having to >> modify its source code. >> >> For backwards compatibility leave previous values as default. > Why do we need to maintain backwards compatibility? Isn't is required > that the nodes have clocks properties? > > this driver -apcs clock controller- uses platform data (not DT) and therefore it uses the DT from the parent node (mailbox). And for the mailbox the clock property is optional. So the APCS clock controller requires that the parent provides at least one clock but the clock is not mandatory in the parent DT node. For instance in the case of the msm8916, the parent only provides one clock, just the pll. am I required to modify that platform instead of maintaining backwards compatibility?