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[188.155.176.92]) by smtp.gmail.com with ESMTPSA id k14-20020a170906128e00b006e4b67514a1sm8220151ejb.179.2022.04.28.03.09.02 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 28 Apr 2022 03:09:03 -0700 (PDT) Message-ID: <813bd5f2-38b6-9642-6993-94ad78f5c08a@linaro.org> Date: Thu, 28 Apr 2022 12:09:02 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.7.0 Subject: Re: [PATCH 08/10] ARM: dts: exynos: use proper 'dma-channels/requests' properties Content-Language: en-US To: Marek Szyprowski , Rob Herring Cc: devicetree@vger.kernel.org, Dinh Nguyen , Lee Jones , Rob Herring , Krzysztof Kozlowski , Sudeep Holla , Michal Simek , Lorenzo Pieralisi , Scott Branden , Sylwester Nawrocki , linux-samsung-soc@vger.kernel.org, Broadcom Kernel Team , linux-kernel@vger.kernel.org, Alim Akhtar , Liviu Dudau , Ray Jui , linux-arm-kernel@lists.infradead.org References: <20220427155840.596535-1-krzysztof.kozlowski@linaro.org> <20220427155840.596535-9-krzysztof.kozlowski@linaro.org> <5eeac2a0-4293-675e-9dc2-25ed8ab3fb8f@samsung.com> <6981f93a-ef01-6ba0-4451-26526372d666@linaro.org> <05c908ce-217f-6938-6745-7405ac39d8ea@samsung.com> <1399774c-f188-81f1-4d15-367b9d0e4a59@linaro.org> <99c80fb6-c6cc-9370-b93d-ed736c7f2192@samsung.com> From: Krzysztof Kozlowski In-Reply-To: <99c80fb6-c6cc-9370-b93d-ed736c7f2192@samsung.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On 28/04/2022 12:05, Marek Szyprowski wrote: >>>>> I also don't see any code that would read those properties. IMHO they >>>>> should be simply removed at all, at least for the PL330 related nodes. >>>> In current Linux implementation they indeed are not used. Nothing parses >>>> them. However: >>>> 1. They describe (hopefully correct) the hardware. >>>> 2. They might be used by other implementations of pl330 driver. >>>> >>>> I would not remove them from existing sources, but indeed maybe there is >>>> no need to add for new files. >>> What's the point in having dt properties duplicating data that might be >>> read from the driver registers? >> Hm, indeed, there is no point in this. Since they are read from >> registers, what was the idea behind in commit 42cf20980cde? > > #dma-cells is indeed required, but the rest seems to be the cargo-cult > of some kind. Rob, Any guidance from your side? Is there any benefit in describing the hadrware (dma-channels/dma-requests) if the same value can be read from registers? Best regards, Krzysztof