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[188.155.176.92]) by smtp.gmail.com with ESMTPSA id o2-20020a170906768200b006e89514a449sm8021480ejm.96.2022.04.28.03.00.14 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 28 Apr 2022 03:00:15 -0700 (PDT) Message-ID: <1399774c-f188-81f1-4d15-367b9d0e4a59@linaro.org> Date: Thu, 28 Apr 2022 12:00:14 +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 , Lee Jones , Rob Herring , Krzysztof Kozlowski , Alim Akhtar , Dinh Nguyen , Michal Simek , Liviu Dudau , Sudeep Holla , Lorenzo Pieralisi , Ray Jui , Scott Branden , Broadcom Kernel Team , Sylwester Nawrocki , devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Rob Herring 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> From: Krzysztof Kozlowski In-Reply-To: <05c908ce-217f-6938-6745-7405ac39d8ea@samsung.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On 28/04/2022 11:57, Marek Szyprowski wrote: > On 28.04.2022 11:54, Krzysztof Kozlowski wrote: >> On 28/04/2022 11:50, Marek Szyprowski wrote: >>> On 27.04.2022 17:58, Krzysztof Kozlowski wrote: >>>> pl330 DMA controller bindings documented 'dma-channels' and >>>> 'dma-requests' properties (without leading hash sign), so fix the DTS to >>>> match the bindings. >>>> >>>> Reported-by: Rob Herring >>>> Signed-off-by: Krzysztof Kozlowski >>> Are those properties really needed for PL330 driver on Exynos SoCs? I've >>> removed them and I still see the proper values read from registers and >>> reported in the log (Exynos4210): >>> >>> dma-pl330 12680000.dma-controller: Loaded driver for PL330 DMAC-141330 >>> dma-pl330 12680000.dma-controller:       DBUFF-32x4bytes Num_Chans-8 >>> Num_Peri-32 Num_Events-32 >>> dma-pl330 12690000.dma-controller: Loaded driver for PL330 DMAC-141330 >>> dma-pl330 12690000.dma-controller:       DBUFF-32x4bytes Num_Chans-8 >>> Num_Peri-32 Num_Events-32 >>> dma-pl330 12850000.dma-controller: Loaded driver for PL330 DMAC-141330 >>> dma-pl330 12850000.dma-controller:       DBUFF-64x8bytes Num_Chans-8 >>> Num_Peri-1 Num_Events-32 >>> >>> 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? Best regards, Krzysztof