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Thu, 01 Oct 2026 08:41:31 -0700 (PDT) X-Received: by 2002:a17:903:2f90:b0:2dd:ad73:c98d with SMTP id d9443c01a7336-2e2e4b4c6b6mr40600035ad.37.1790869290901; Thu, 01 Oct 2026 08:41:30 -0700 (PDT) Received: from [192.168.0.116] ([124.123.146.251]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2e300b0834esm12975265ad.51.2026.10.01.08.41.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 01 Oct 2026 08:41:30 -0700 (PDT) Message-ID: <47a155fc-9cde-48fd-bb02-31a7d3d9e8dd@oss.qualcomm.com> Date: Thu, 1 Oct 2026 21:11:22 +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 net-next v2 1/2] dt-bindings: net: qcom,bam-dmux: Add memory-region and qcom,vmid properties To: netdev-bot+sashiko@kernel.org Cc: stephan@gerhold.net, andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org, loic.poulain@oss.qualcomm.com, ryazanov.s.a@gmail.com, johannes@sipsolutions.net, linux-arm-msm@vger.kernel.org, netdev@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, deepak.singh@oss.qualcomm.com References: <20260920-qcom-bam-dmux-vmid-ext-v2-1-ef5ca2178378@oss.qualcomm.com> <178996250211.2160803.6013516663876593386@kernel.org> Content-Language: en-US From: Vishnu Santhosh In-Reply-To: <178996250211.2160803.6013516663876593386@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Proofpoint-GUID: 2dZPmHWET2LhJyAvHmp6Z5x0AwFJDSC4 X-Proofpoint-ORIG-GUID: 2dZPmHWET2LhJyAvHmp6Z5x0AwFJDSC4 X-Authority-Analysis: v=2.4 cv=O8SsLx9W c=1 sm=1 tr=0 ts=6abe7f2c cx=c_pps a=IZJwPbhc+fLeJZngyXXI0A==:117 a=K/78aEDNEn2Q/Yuv7mVN5Q==:17 a=IkcTkHD0fZMA:10 a=660iZSQnnn4A:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=eoimf2acIAo5FJnRuUoq:22 a=VwQbUJbxAAAA:8 a=Xq0XWdt-4rZHMzWQs8gA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 a=uG9DUKGECoFWVXl0Dc02:22 X-Proofpoint-Spam-Info: AW1haW4tMjYxMDAxMDA2MiBTYWx0ZWRfX4uSnD3gvHirx nhjF/Mniv9HICbvFP3Hv5t/cybtaIP/YOTu4ike/L0LqTBwj4Q3l33Vr18nvWmuD+djK8cYdKF9 gUoIoNzBv5jfmm6/zY3AzBMRb3RJHcs= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMDAxMDA2MiBTYWx0ZWRfX5h5ZKgf8gTrM QLnaZ8zLetavq0JL/VTQ/krC67vJwmmecXclBzLaFXgBavRksjxSZxkMugWN3irioTPl5WFK80S pVzq2vdJ/hPm8fL7kVniOw46XAVK6x/pYKHxgneo24bRI+LGrj5hanMrbu1D/2RPU13O4YM36v4 PnzYnEWvSCSZy19GRKxDB56oQBtOd+QDHL4S7AaFSPRKZ602V1dB0OWE5WdtF2hfxYmQi60w0OZ RqFZ6lrHzSB3cqO1rBmz827lG0do1LEUQP8MPTWtmuDjE2kmgqiiePB4IGwgnihsCVz5Z0clkRV fwD3eZMB4jtqgswmogPgcmfiTY4uVwT0jF+8SDPZc989IrtenqsiHjAWpSoMOW0X02PRzlFg8qV RtOAN86WGtOOqt4x1ZpVaPUdNZjZVrKfWc18rSxnsgUgLWlSPXdCLVW7yYfAGT5eWdOnbchmLTm x5VSuFAlTB94cBPCFqw== 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=2026-10-01_04,2026-09-21_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 lowpriorityscore=0 clxscore=1015 adultscore=0 bulkscore=0 phishscore=0 impostorscore=0 suspectscore=0 priorityscore=1501 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2610010062 On 21-09-2026 09:18 am, netdev-bot+sashiko@kernel.org wrote: > Thank you for your contribution! Sashiko AI review found more severe > issue(s) in other patches of this series. This mail is only an FYI, in case > you want to address the nit picks below when you respin. > > Low priority / nit picks for your consideration: > > - [Low] SERIES-RESOLVED (retained for policy combination only): the > concern that the newly documented `qcom,vmid`/`memory-region`… > - [Low] The `qcom,vmid` schema contradicts its own description: the > description states "The local execution environment is retained… > > -- > > dt-bindings: net: qcom,bam-dmux: Add memory-region and qcom,vmid properties > > This adds an optional memory-region property pointing at a > restricted-dma-pool reserved-memory node for BAM-DMUX DMA mappings, plus a > qcom,vmid property naming the remote execution environment that is granted > access to that pool via SCM. A dependency entry makes memory-region > mandatory whenever qcom,vmid is present. > >> diff --git a/Documentation/devicetree/bindings/net/qcom,bam-dmux.yaml b/Documentation/devicetree/bindings/net/qcom,bam-dmux.yaml >> index 33746c238513..5351269b0ab7 100644 >> --- a/Documentation/devicetree/bindings/net/qcom,bam-dmux.yaml >> +++ b/Documentation/devicetree/bindings/net/qcom,bam-dmux.yaml >> @@ -72,6 +72,24 @@ properties: >> - const: tx >> - const: rx >> >> + memory-region: >> + maxItems: 1 >> + description: >> + Phandle to a reserved-memory node compatible with restricted-dma-pool. >> + The BAM-DMUX device uses the pool for DMA mappings. >> + > [Severity: Low] > This isn't a bug, just a note for the record on an earlier concern that > these two properties have no in-tree consumer. > > The companion patch in this series, "net: wwan: qcom_bam_dmux: Assign > restricted DMA pool to remote processor", adds bam_dmux_assign_dma_pool() > in drivers/net/wwan/qcom_bam_dmux.c, which reads qcom,vmid, resolves > memory-region through of_parse_phandle() and of_reserved_mem_lookup(), and > then performs the grant: > > ret = qcom_scm_assign_mem(rmem->base, rmem->size, &src, dst, > ARRAY_SIZE(dst)); > > The pool attachment itself is handled generically by > of_dma_set_restricted_buffer() from of_dma_configure_id(), so the > "uses the pool for DMA mappings" wording is backed by existing code too. > Nothing further appears to be needed here. > >> + qcom,vmid: >> + $ref: /schemas/types.yaml#/definitions/uint32-array >> + minItems: 1 >> + maxItems: 1 >> + items: >> + minimum: 1 >> + maximum: 63 >> + description: >> + VMID of the remote execution environment that is granted access to the >> + restricted DMA pool through SCM. The local execution environment is >> + retained automatically and must not be specified. >> + > [Severity: Low] > Does the numeric constraint on qcom,vmid contradict its own description? > > The description says the local execution environment "must not be > specified", but the only constraints are minimum 1 and maximum 63, and > include/dt-bindings/firmware/qcom,scm.h has: > > #define QCOM_SCM_VMID_HLOS 0x3 > > So qcom,vmid = passes dt_binding_check even though the > binding text declares it invalid. The 1..63 range looks like it encodes the > width of the SCM VMID bitmask used for BIT_ULL(vmid) in a u64, not the set > of values meaningful for this device. > > The driver side in this series does enforce the rule, in > bam_dmux_assign_dma_pool(): > > if (vmid == QCOM_SCM_VMID_HLOS || vmid >= BITS_PER_TYPE(u64)) > return dev_err_probe(dev, -EINVAL, "Invalid qcom,vmid %u\n", vmid); > > so the outcome of a bad value is a probe failure rather than anything worse. > Would it make sense to encode the same restriction in the schema, for > example with a not/const 3 clause or an enum of the supported remote > execution environments, or otherwise drop the "must not be specified" > sentence so the prose and the schema agree? I plan to drop the "must not be specified" sentence in the next revision, so the prose and the schema agree. Thanks, Vishnu > > For context, neither qcom,rmtfs-mem.yaml nor qcom,fastrpc.yaml places value > constraints on their qcom,vmid / qcom,vmids properties, so an enum here > would be a new convention rather than an existing one; the narrow point is > just the internal inconsistency in this file. > > [ ... ] >