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([2a02:810d:15c0:828:52e:24ce:bbc1:127d]) by smtp.gmail.com with ESMTPSA id x2-20020aa7d6c2000000b0050bd47f9073sm2906899edr.39.2023.05.05.05.23.21 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 05 May 2023 05:23:21 -0700 (PDT) Message-ID: <3d9d545d-a620-85f6-b7bd-d57a8729f818@linaro.org> Date: Fri, 5 May 2023 14:23:20 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.10.1 Subject: Re: [PATCH 7/7] dt-bindings: dmaengine: pl330: Add new quirks Content-Language: en-US To: Joy Chakraborty Cc: Vinod Koul , Rob Herring , Krzysztof Kozlowski , dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, manugautam@google.com, danielmentz@google.com, sjadavani@google.com References: <20230504145737.286444-1-joychakr@google.com> <20230504145737.286444-8-joychakr@google.com> <78616bc1-8d9e-4a1c-70d6-ad62c2cfa8a8@linaro.org> From: Krzysztof Kozlowski In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/05/2023 11:44, Joy Chakraborty wrote: > On Thu, May 4, 2023 at 8:38 PM Krzysztof Kozlowski > wrote: >> >> On 04/05/2023 16:57, Joy Chakraborty wrote: >>> Add 2 new quirks added to the driver "arm,pl330-optimize-dev2mem-axsize" >>> and "arm,pl330-periph-single-dregs" >> >> This we can see from the diff. You need to answer why? >> > > Sure will change it to: > " > Addition of following quirks : > - "arm,pl330-periph-use-diff-axsize" > AxSize of transactions to peripherals are limited by the peripheral > address width which inturn limits the AxSize used for transactions > towards memory. > This quirk will make transactions to memory use the maximum > possible bus width(AxSize), store data in MFIFO and use narrow > multi-beat transactions to move data to peripherals. > This only applies to transfers between memory and peripherals where > bus widths available are different for memory and the peripheral. > - "arm,pl330-periph-complete-with-singles" : > When transfer sizes are not a multiple of a block of burst > transfers (AxLen * AxSize configured at the peripheral), certain > peripherals might choose not to set the burst request at the > peripheral request interface of the DMA. > This quirk moves the remaining bytes to the peripheral using single > transactions. > " This does not answer why. You just copied again the patch contents. > >>> >>> Signed-off-by: Joy Chakraborty >>> --- >>> Documentation/devicetree/bindings/dma/arm,pl330.yaml | 8 ++++++++ >>> 1 file changed, 8 insertions(+) >>> >>> diff --git a/Documentation/devicetree/bindings/dma/arm,pl330.yaml b/Documentation/devicetree/bindings/dma/arm,pl330.yaml >>> index 4a3dd6f5309b..0499a7fba88d 100644 >>> --- a/Documentation/devicetree/bindings/dma/arm,pl330.yaml >>> +++ b/Documentation/devicetree/bindings/dma/arm,pl330.yaml >>> @@ -53,6 +53,14 @@ properties: >>> type: boolean >>> description: quirk for performing burst transfer only >>> >>> + arm,pl330-optimize-dev2mem-axsize: >>> + type: boolean >>> + description: quirk for optimizing AxSize used between dev<->mem >> >> This tells me nothing... Neither what it is about nor why this is >> property of a board or PL330 hardware implementation. Please describe >> hardware, not drivers. >> > > Will change the name to "arm,pl330-periph-use-diff-axsize" and add description: > " > Quirk to use different AxSize for bursts while accessing source and > destination when moving data between memory and peripheral. > Maximum possible bus width is used as AxSize for transactions towards > memory and transactions towards peripherals use AxSize as per > peripheral address width. > " Still no answer. Why this is property of a board or PL330 hardware implementation? I also asked to describe hardware but I still see "quirk to ...". We use "quirk" as concept in Linux driver. Describe the hardware, not Linux driver. > >>> + >>> + arm,pl330-periph-single-dregs: >>> + type: boolean >>> + description: quirk for using dma-singles for peripherals in _dregs() >> >> Same concerns. >> > > Will change the name to "arm,pl330-periph-complete-with-singles" and > add description: > " > Quirk to use dma singles n times instead of an n beat burst to > complete a transfer when the transfer size is not a multiple of the No, how you wrote it sounds like driver. Don't add driver quirks to DT. Best regards, Krzysztof