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Fri, 10 Jul 2026 20:56:00 -0700 (PDT) X-Received: by 2002:a05:6a21:d88:b0:3b3:a66e:3911 with SMTP id adf61e73a8af0-3c0f0ae84bbmr7014136637.19.1783742160202; Fri, 10 Jul 2026 20:56:00 -0700 (PDT) Received: from [192.168.0.116] ([124.123.151.85]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-13b658a99afsm43281978c88.0.2026.07.10.20.55.56 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 10 Jul 2026 20:55:59 -0700 (PDT) Message-ID: Date: Sat, 11 Jul 2026 09:25:54 +0530 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] arm64: dts: qcom: shikra: Add BAM-DMUX support To: Stephan Gerhold Cc: Bjorn Andersson , Konrad Dybcio , Rob Herring , Krzysztof Kozlowski , Conor Dooley , linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, bjorn.andersson@oss.qualcomm.com, chris.lew@oss.qualcomm.com References: <20260611-qcom-shikra-dts-bam-dmux-v1-1-43d0b43d41ef@oss.qualcomm.com> <17bfa853-d0a6-4f83-a164-a17fb02f67a6@oss.qualcomm.com> Content-Language: en-US From: Vishnu Santhosh In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Proofpoint-Spam-Info: AW1haW4tMjYwNzExMDAzNCBTYWx0ZWRfX0F64tdItH+Pv vuxsWDeyWBmmjAxyy5FL8TFEtxnBXb9lsX4QHjK3mS/pBCEZJEA+5PCEjayTd1eLXEwQkZdI7fe 9LfPCqrTCf8lrZJ4V69YFHT7Ic3p+/Y= X-Proofpoint-GUID: NA90TBGlwQyQa9sU3sC3HENAY1xQyN0d X-Proofpoint-ORIG-GUID: NA90TBGlwQyQa9sU3sC3HENAY1xQyN0d X-Authority-Analysis: v=2.4 cv=dJSWXuZb c=1 sm=1 tr=0 ts=6a51bed1 cx=c_pps a=rz3CxIlbcmazkYymdCej/Q==:117 a=ziBI+Y3eO/H+UwYWWny9Hg==:17 a=IkcTkHD0fZMA:10 a=RAioF0-LDSMA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=gowsoOTTUOVcmtlkKump:22 a=VwQbUJbxAAAA:8 a=EUspDBNiAAAA:8 a=KhpSxh-dhdghoZIDTE8A:9 a=QEXdDO2ut3YA:10 a=bFCP_H2QrGi7Okbo017w:22 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzExMDAzNCBTYWx0ZWRfXxaCU/UMdrbxm NbEaBKQMC5FWeeNV/Cs17z7DPq1hRNd7yIh7X62XfCQRHElh4dlVZleNKSdKUijdMkWA1W/nwOv ZfJb4ltERFYJWxfw8A6a6fungCuIXVzIy9l2FWgfv/Vs5fNMAogKJ4k6GF916Z+G0D/oEluz9Nm Fjn5Gt3LTZnI+0lhAahI04XTdhXc9Fioc1PkQdH612sWnFfsOjxvdiAS73DD9YIUDmwOm2mFVD+ mwB+zIDNDmF3OIW4yh8WSZ0ldD6g6qwXdcR55ZEG9N+jmAN/i3tR0qkLxeB4W57kksTySwQ1N/P jLOvdjSOiFyFYu+omEVOED4lxzT2iSECUF89aC4UHE+D66bSoTdQ3wzoDZHYN+2VUfIymfXMk+z nN+HIhclb6Qhe1MOb0ChEyOQ4X9hi66Bkc52/zTDuPzbW8q16f9IjaSDHsicnqRPAav/LHu3nvg bxOKzS0jh9yGUkkdLHw== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-07-11_01,2026-07-10_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 impostorscore=0 suspectscore=0 phishscore=0 clxscore=1015 spamscore=0 priorityscore=1501 lowpriorityscore=0 adultscore=0 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607110034 On 11-06-2026 10:27 pm, Stephan Gerhold wrote: > On Thu, Jun 11, 2026 at 09:31:06PM +0530, Vishnu Santhosh wrote: >> On 11-06-2026 02:25 pm, Stephan Gerhold wrote: >>> On Thu, Jun 11, 2026 at 02:11:59PM +0530, Vishnu Santhosh wrote: >>>> + bam_dmux: bam-dmux { >>>> + compatible = "qcom,bam-dmux"; >>>> + >>>> + interrupts-extended = <&modem_smsm 1 IRQ_TYPE_EDGE_BOTH>, >>>> + <&modem_smsm 11 IRQ_TYPE_EDGE_BOTH>; >>>> + interrupt-names = "pc", >>>> + "pc-ack"; >>>> + >>>> + qcom,smem-states = <&apps_smsm 1>, >>>> + <&apps_smsm 11>; >>>> + qcom,smem-state-names = "pc", >>>> + "pc-ack"; >>>> + >>>> + dmas = <&bam_dmux_dma 4>, <&bam_dmux_dma 5>; >>>> + dma-names = "tx", "rx"; >>>> + }; >>> This should be a child node of the modem remoteproc. See msm8916.dtsi >>> for example. >> Thanks for the context! We actually referenced msm8916.dtsi during bring-up >> and initially placed bam-dmux as a >> remoteproc child. We then hit the issue that the driver was not probing at >> all. After some digging, we realized >> that qcom_q6v5_mss.c (used by msm8916) explicitly calls >> of_platform_device_create() for its qcom,bam-dmux child, >> but qcom_q6v5_pas.c which Shikra uses has no such logic, so the platform >> device was never created. >> >> There was a prior attempt to fix this generically by adding >> of_platform_populate() to qcom_q6v5.c >> (https://lore.kernel.org/all/20251223123227.1317244-3-gaurav.kohli@oss.qualcomm.com/), >> but it was blocked >> because GLINK/SMD edge child nodes would also get spurious platform devices >> registered for them. >> That series remains unresolved at v1. >> >> Since your driver already manages modem lifecycle independently via SMSM >> state bits without remoteproc dependency, >> we moved it to the root level where of_platform_populate() picks it up at >> boot, and everything worked. >> >> Would love to get your suggestion on whether this approach is welcomed, >> since it needs zero driver changes. >> > Adding the bam-dmux node top-level makes it impossible for userspace to > associate it with a remoteproc (for this purpose: the "modem"). If you > add it below the remoteproc the udev/sysfs path will include the > remoteproc and you can tell that the network interfaces exposed by > bam_dmux belong to that remoteproc. > > As you noticed, having a generic of_platform_populate() for remoteproc > nodes is problematic, because usually subnodes are remoteproc subdevs. > Also, the cooling device use case in the thread you linked doesn't have > any resources attached, so the root complaint there was that you don't > need a separate subnode at all. > > I would just replicate the special qcom,bam-dmux logic inside > qcom_q6v5_pas.c. I think the motivation for BAM-DMUX explained in commit > 59983c74fc42 ("remoteproc: qcom_q6v5_mss: Create platform device for > BAM-DMUX") is still valid. Conceptually, BAM-DMUX is a subdevice of the > modem remoteproc, since the remoteproc is responsible for powering the > BAM-DMUX hardware on and off. The fact that BAM-DMUX is not a remoteproc > subdev in Linux is more an implementation detail of the current Linux > driver. This is independent from the model in the device tree. > > Thanks, > Stephan Thanks for the guidance. This makes sense. I'm preparing an update to incorporate the DT changes and replicate the BAM-DMUX platform device creation logic in qcom_q6v5_pas.c as suggested. Thanks, Vishnu