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[188.141.3.169]) by smtp.gmail.com with ESMTPSA id x7-20020a1c7c07000000b003ffca80edb8sm11181146wmc.15.2023.08.28.08.43.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 28 Aug 2023 08:43:09 -0700 (PDT) Message-ID: <2d26595f-8a74-04a5-b62b-c4383ffa7dc8@linaro.org> Date: Mon, 28 Aug 2023 16:43:08 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 Subject: Re: [PATCH v3 15/15] media: qcom: camss: Comment CSID dt_id field Content-Language: en-US To: Konrad Dybcio , rfoss@kernel.org, todor.too@gmail.com, agross@kernel.org, andersson@kernel.org, mchehab@kernel.org, hverkuil-cisco@xs4all.nl, laurent.pinchart@ideasonboard.com, sakari.ailus@linux.intel.com, andrey.konovalov@linaro.org Cc: linux-media@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org References: <20230823104444.1954663-1-bryan.odonoghue@linaro.org> <20230823104444.1954663-16-bryan.odonoghue@linaro.org> <4929aa72-a134-4eeb-850e-46d9255c011b@linaro.org> <8310417c-bba9-49ed-9049-bee5b23c2e3f@linaro.org> From: Bryan O'Donoghue In-Reply-To: <8310417c-bba9-49ed-9049-bee5b23c2e3f@linaro.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org On 28/08/2023 16:38, Konrad Dybcio wrote: > On 28.08.2023 17:34, Bryan O'Donoghue wrote: >> On 26/08/2023 11:18, Konrad Dybcio wrote: >>>> +        /* >>>> +         * A value caled 'CID' gets generated internal to CAMSS logic >>>> +         * which is a concatenation of [vc:6 | dt_id:2] hence we reuse >>>> +         * the least significant two bits of the VC to 'stuff' the CID value. >>>> +         */ >>>>           u8 dt_id = vc; >>> And where are you discarding the non-2-lsb? >> >> At the assignment of dt_id >> >> vc:6 >> dt_id:2 >> >> => >> >> cid:8 = [vc:6 | dt_id:2] >> vc == 00110110 >> cid = [110110 | 10] >> >> I have no more information what CID is or how the bitfield is populated than I have already indicated in the comment/commit log. >> > OK so you're discarding the 2 lsb of the [vc:6|dt_id:2] > > however > > the way I read the comment would suggest that you're taking > vc[6:2] > > Konrad Fair enough, obvs the comment needs work so. --- bod