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[199.106.103.254]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-1b50319e381sm1541771c88.12.2026.11.12.13.44.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 12 Nov 2026 13:44:12 -0800 (PST) Date: Thu, 12 Nov 2026 13:44:07 -0800 From: Jonathan Cameron To: Cristian Marussi Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, arm-scmi@vger.kernel.org, linux-doc@vger.kernel.org, sudeep.holla@kernel.org, james.quinlan@broadcom.com, f.fainelli@gmail.com, vincent.guittot@linaro.org, etienne.carriere@st.com, peng.fan@oss.nxp.com, michal.simek@amd.com, d-gole@ti.com, elif.topuz@arm.com, lukasz.luba@arm.com, philip.radford@arm.com, david@kernel.org, souvik.chakravarty@arm.com, leitao@kernel.org, kas@kernel.org, puranjay@kernel.org, usama.arif@linux.dev, kernel-team@meta.com Subject: Re: [PATCH v15 23/35] firmware: arm_scmi: Add Telemetry generation counter event Message-ID: <20261112134407.0000457f@oss.qualcomm.com> In-Reply-To: References: <20261109091221.2532706-1-cristian.marussi@arm.com> <20261109091221.2532706-24-cristian.marussi@arm.com> <20261110144635.00005964@oss.qualcomm.com> Organization: Qualcomm X-Mailer: Claws Mail 4.4.0 (GTK 3.24.51; x86_64-w64-mingw32) X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMTEyMDA4NiBTYWx0ZWRfX6DV1HnCFxSqm R8jcMMj1ZjwuiHsNq32zZNzGTeNi2uikgV+xzOBmRvk86G6Do28C4xbl0RLT1Xie5g028gyI82a nOow+x67vJcu/+51bOulz0Tt6R03kB+ZigX/JJw3WlTayY4n2gE4CXz9mNkrGk9U7/HNfTD6lxl lQ9LlNN35fu+LYqSKzTXGc470oMSNISx6dIAq0Zt/Wfrl0Y/GZNpIvJUI0TWyROgZS2S2vMpyP9 QTBIVn87gzEtRVf8l3TergO1spHl3aS3tojXjwVk1Kx7Am/GZOme2pZmVldLqvCuJtueGxAAbkp tjRhzCvaA8aATAIN5q5Ks7C92EwqbbXAxerH025cimne3ly9WzNTyQEYF7tW38sIeNLrTBKwBOi PB0R4nGfS4gu7gO/nUJFSt3aMknXisO65CK3mygNSQ9NOUeou0YQ/lOxqmk97Fggf3RZ22VHYg2 JI4NZmZ/1AbRq++avZg== X-Proofpoint-GUID: WmeZBARnji6E96zbF6VwwuCoElL6AXi6 X-Proofpoint-ORIG-GUID: WmeZBARnji6E96zbF6VwwuCoElL6AXi6 X-Authority-Analysis: v=2.4 cv=F6fC5ahN c=1 sm=1 tr=0 ts=6af6332d cx=c_pps a=SvEPeNj+VMjHSW//kvnxuw==:117 a=JYp8KDb2vCoCEuGobkYCKw==:17 a=kj9zAlcOel0A:10 a=zJRp6_cAMcgA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=rJkE3RaqiGZ5pbrm-msn:22 a=7CQSdrXTAAAA:8 a=reF3IxvR5ta2O57t2W8A:9 a=CjuIK1q_8ugA:10 a=Kq8ClHjjuc5pcCNDwlU0:22 a=a-qgeE7W1pNrGK8U0ZQC:22 X-Proofpoint-Spam-Info: AW1haW4tMjYxMTEyMDA4NiBTYWx0ZWRfX0FZNXRgiBs6v 9YBRqaXy1XNaKn0p3s1f0iXlOs3xnk+dl+11O8gw+hf88IfN+z42G+/HUTibvu7hvS4poAdZ+XD zqPdQLa0znWiqrFxN+crQEc8KX2hZP8= X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.138,FMLib:17.12.100.49 definitions=2026-11-12_03,2026-11-11_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 impostorscore=0 malwarescore=0 spamscore=0 clxscore=1015 bulkscore=0 phishscore=0 lowpriorityscore=0 adultscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2611040001 definitions=main-2611120086 On Thu, 12 Nov 2026 20:17:35 +0000 Cristian Marussi wrote: > On Tue, Nov 10, 2026 at 02:46:35PM -0800, Jonathan Cameron wrote: > > On Mon, 9 Nov 2026 09:12:09 +0000 > > Cristian Marussi wrote: > > > > > Add a per-instance generation counter to track configuration changes which > > > uses the common telemetry events framework. > > Why? What's the usecase for this? > > Needs some more information or I'd leave it for now. > > > > SCMI Telemetry is specified and designed FW/Kernel side to allow for > multiple readers and multiple writers issuing configuration changes: > give that there is NO HW/FW/SPEC limitation in allowing such concurrency > (unlike e.g. for a serial or an RTC) the telemetry driver does NOT > enfroce any kind of exclusive access...last one wins when multiple > acctors tries to configure overlapping stuff...none of kernel problem > userspace should co-ordinate...and I suspect most of the time having > multiple apps trying to concurrently issue conflicting Telemetry request > would be a matter of wrong platform configuration/setup (similarly to > what would happen by running together all the lovely varied network > configiratio solution on a Linux box...) > > As said the Kernel SHOULD NOT care, going back to the networking example > Kernel indeed does NOT active policy netlink access..you are free to shot > into your foot... > > Anyway, co-ordinating access to the Telemetry resources in userspace can > be a pain, so the the generation counter is an optional mechanism to be > alerted when some of the Telemetry has been changed, so that userspace > can spot that something odd is happening (if it was unexpected) and > avoid to sample and analyze bogus data... > > The generic event support upon which this is based, it is meant to > support future events like relaying notifications to userspace...but > given that notifs were NOT implemented for real, it is not present (NOR > the related ABI...) > Ok. That explanation makes sense. Given it effects how userspace will be written against this stack (maybe assuming folk don't just bind a single daemon process to it) it does have to be there fairly early. Maybe a follow up to the initial set like the stuff for already events. Anyhow, add this info to the patch description! Jonathan > Thanks, > Cristian