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Tue, 15 Sep 2026 06:18:13 -0700 (PDT) X-Received: by 2002:a05:620a:7018:b0:93a:3257:34b with SMTP id af79cd13be357-93a346fa956mr478716285a.29.1789478292807; Tue, 15 Sep 2026 06:18:12 -0700 (PDT) Received: from [192.168.68.120] ([5.133.47.210]) by smtp.googlemail.com with ESMTPSA id a640c23a62f3a-c2966067117sm597020266b.33.2026.09.15.06.18.11 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 15 Sep 2026 06:18:11 -0700 (PDT) Message-ID: Date: Tue, 15 Sep 2026 14:18:11 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/3] soundwire: qcom: add multi-master support To: Pierre-Louis Bossart , robh@kernel.org, vkoul@kernel.org Cc: krzk+dt@kernel.org, conor+dt@kernel.org, srini@kernel.org, yung-chuan.liao@linux.intel.com, prasad.kumpatla@oss.qualcomm.com, jingyi.wang@oss.qualcomm.com, sibi.sankar@oss.qualcomm.com, quic_srivasam@quicinc.com, linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-sound@vger.kernel.org References: <0097b59e2b96d692b9fb542e207ee43f9dd44a7f.1789114385.git.srinivas.kandagatla@oss.qualcomm.com> <8c6bfa54-83a7-4d37-bbc8-d3384dfc6ce2@linux.dev> Content-Language: en-US From: Srinivas Kandagatla In-Reply-To: <8c6bfa54-83a7-4d37-bbc8-d3384dfc6ce2@linux.dev> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Proofpoint-ORIG-GUID: smsE6crPGbO1Wk_5moZjaox2bGKZbn2V X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTE1MDE5MiBTYWx0ZWRfX2rdZMQA7DYwW WL8SMx/egNgTncnYrRST8b8fkaAu/v4lMS1XK7VQN5rz2vUc40TwT6m2kaK+fGKXpzvi/MTo7My KgdY+WvjZpOuBZll6sPF0qFkp1OFcpkal6zfho7OcMMQbjfabWr4bxKZl7nPraWHBiJp2Ss5uOd eAHPazDvopBnX0KMOggyRHauSfeyml3F8u9RYI7++Mc+8i1MpUtTswR+jsS5KQD68Bdh2xBTuc9 5IhRKzdAg7Sjjn3iv0vox81led4yWuLsj5L8JwMZIo7UrFWYhuaosQ9UfnuX9pC74Dnk5VyxRMC ebu3HJcch1Zo25yM98pT1F1Z+WjGOOZo3Ji4inmdXyy7e7cFE7IdjjccmcDraqx1uCCMgJxALDF MInLCV6H0eRZ8bmHc1xfQdON3oDk/s1qauNeCJyIVObJ9jC7yyv/RQ/esbO3T9+hqlqmre9HhbG DfWHezm7rU1V++RW39g== X-Proofpoint-Spam-Info: AW1haW4tMjYwOTE1MDE5MiBTYWx0ZWRfX1RoZTsMhjSGi 6qdC1njE11V5dBFlNcBcEk+897ad5emjq/b0pt4Y4rBGmzInAtE+YjSqCg8jtGdk2pgmPX7O851 R9ghUOTCOEqJDEUw9tGRkV0q4yBwLWE= X-Proofpoint-GUID: smsE6crPGbO1Wk_5moZjaox2bGKZbn2V X-Authority-Analysis: v=2.4 cv=IcISymqa c=1 sm=1 tr=0 ts=6aa94596 cx=c_pps a=hnmNkyzTK/kJ09Xio7VxxA==:117 a=ZsC4DHZuhs/kKio7QBcDoQ==:17 a=IkcTkHD0fZMA:10 a=VdqzKS8jKosA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=ZpdpYltYx_vBUK5n70dp:22 a=Oxe59_bkntSI8SC7MgYA:9 a=QEXdDO2ut3YA:10 a=PEH46H7Ffwr30OY-TuGO:22 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-09-15_04,2026-09-14_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 impostorscore=0 lowpriorityscore=0 priorityscore=1501 adultscore=0 bulkscore=0 clxscore=1015 malwarescore=0 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2609150192 On 9/14/26 6:21 PM, Pierre-Louis Bossart wrote: > On 9/11/26 10:21, Srinivas Kandagatla wrote: >> v3.1.0+ Qualcomm SoundWire IPs can be paired to expose one logical >> bus with more than two DATA lanes. One IP owns SWR_CLK and drives >> the bus; the other contributes DATA lanes only. >> >> Support this pairing on the driver side. A device link between the >> two IPs enforces correct unbind ordering and keeps the peer resumed >> while the primary is active. >> >> Single-master deployments (no qcom,multi-master-mode in DT) are >> unaffected. > > It'd be good to clarify how the command protocol is handled. Each IP is > probably capable of handling PING/READ/WRITE commands in Column0, but in > the paired option the primary IP is the only one that deals with Column0 > and all other DATA lanes are just data? All the control/command is only handled by Primary controller, dependent controllers only contribute to additional data lines. only Primary handles slave register reads/writes. I will clarify this in next version. thanks, Srini >