From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 801CE3AE187; Mon, 10 Aug 2026 10:28:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786357730; cv=none; b=nFEFu+a5rTXbmcA2d6WQF9x02+VePOgbo3fJrcYg43P0LzAV0L2LlyIojZfFnUnM6oX3D6XAjMmBgrBGom7xqUBg2D4+1nvOoILtGXkeC7HMgwQbw4k1wU9jINE4f5M8tt9LIXE2mkLwudxmG/dOlZbOXW5Zx+gTSKzvp7iYwgQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786357730; c=relaxed/simple; bh=maqLFykox4FH0KHiP8TnBxvurfPRTkEhw7HCpnqJSOI=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=FLuh3vMFE4UmdV9Yhb8CcmnNBp3qZiPgN94YYUPLU8pPoTkUXueH0JkXev32xumqep+MTPCCe4uw1PI//BK2YhK2ywy5SjmHmdZ5qtxAxQAsn1jjNVPI57O2HiMaFiXHMqoS6Dg8nG+4LSVxk559FeIrNuOpmuJIKsZUdJgm4yU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=VNWlz5is; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="VNWlz5is" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1EC5B1F000E9; Mon, 10 Aug 2026 10:28:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786357728; bh=HgXIrs2B3DfHBP5nxGyXdoxDZ3P+3le6QMIeyZwLRVM=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=VNWlz5isL+Wt0l8KtVvJpm0kw1mzGgAyZajrwxKfI7Pf0qgoMF33QcDhFAN4nJV/Y j06/8hXpGIkUiM0CDqI43+YLSqK+2eoPaFcKytISFTkM4NP5AjhFlXTGFDbPUjGB5W 3Afd1IU2O40xsmCrVHb9a+BmmOs3C+NCdRD7Yi9nKiG4ingJxgmyr+hmV3S1xlrqbS qBm/0Gqe1+z7Yoa3upftAHXC9SF3aJm39IlHcbHI6eX6YVkmyN6GmxKPsrzVEM+8HW suSFs+u4pASKoE3AXWQ181pZ9RPwZfLLfuRYl3LMHdU6rHR28RFzAM7lmvDz+oA3r4 HjNeuwD0NfZhQ== Message-ID: <5330838e-d3f0-454a-b856-bd8fc3e941aa@kernel.org> Date: Mon, 10 Aug 2026 12:28:36 +0200 Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/6] dt-bindings: bluetooth: qca: add QCC2072 To: Dmitry Baryshkov , Manivannan Sadhasivam Cc: Rahul Samana , Bartosz Golaszewski , Marcel Holtmann , Luiz Augusto von Dentz , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Balakrishna Godavarthi , Rocky Liao , Bjorn Andersson , Konrad Dybcio , Bartosz Golaszewski , linux-arm-msm@vger.kernel.org, linux-bluetooth@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linux-pm@vger.kernel.org, quic_mohamull@quicinc.com, quic_hbandi@quicinc.com, quic_anubhavg@quicinc.com References: <6d6465bb-47ac-464c-af4e-0ca72325705f@oss.qualcomm.com> <8a388310-d3cc-4d02-abb6-0eb98c24cfce@kernel.org> <4523441f-498a-4bbd-80f3-97a7a9206c00@oss.qualcomm.com> <6e0b9e79-ccd4-4689-9a6b-9b4fc556d5e4@kernel.org> <8ab6c26f-b648-447c-9fdd-f1424beb44f4@kernel.org> <768142f0-2638-41f3-a34f-dc80bb99eb7f@kernel.org> <5tkajres2vjkt436teaujcqyc3mjqr65rsfvwhjbmlk3fc3gpt@j6ozyfattae3> <2iymaoj6ryayvsyfnrkwf6ldq57lkitoyqrazytxh7wxnpeoeo@vg6q35cua2oy> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 07/08/2026 11:40, Dmitry Baryshkov wrote: > On Wed, Aug 05, 2026 at 04:52:15PM +0200, Manivannan Sadhasivam wrote: >> On Wed, Aug 05, 2026 at 04:36:31PM +0200, Krzysztof Kozlowski wrote: >>> On 05/08/2026 16:12, Manivannan Sadhasivam wrote: >>>> On Wed, Aug 05, 2026 at 02:33:51PM +0200, Krzysztof Kozlowski wrote: >>>>> DT is not representation of internal device driver instantiation mechanism. >>>>> >>>> >>>> Here, the driver is just creating compatible for a real device. What difference >>>> does it make if the BT node was defined statically in the DT vs created >>>> dynamically? Both nodes do represent a real BT device, not driver's own >>>> representation. And by the time the node was created, the device is physically >>>> attached to the system. >>> >>> What stops this power sequencing drivers, after more driver patches, the >>> best if being part of some bigger series, to add properties like >>> "linux,name-of-driver-to-bind" or whatever other SW properties? >>> >>> This is what happened in that linked thread: >>> https://lore.kernel.org/all/20260326-pci-m2-e-v7-8-43324a7866e6@oss.qualcomm.com/ >>> The driver code is adding children under other nodes (references by >>> graph) and it is nowhere documented. Maybe bindings of these other nodes >>> allow it, maybe not. How do you even validate that? >>> >> >> So the concern is validating the properties that get added dynamically and I get >> that. How about inserting an overlay for the BT node instead of creating the >> node on the fly? Like, drivers/misc/lan966x_pci.dtso >> >> This way, the overlay would be validated against a binding and the driver would >> just be inserting it. >> >>> So answering your question - yes, there is a difference because: >>> 1. DTS we validate but whatever you add to driver code we do not and we >>> cannot, >>> 2. DTS represents hardware but whatever you do in your driver code >>> represents who knows what (maybe hardware, maybe not, can represent >>> anything) >>> >>> And if you claim "I add hardware in the driver!", I respond - maybe >>> true, maybe not, but look at this crap: >>> https://web.git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=687bfbba5a1cb15cee51519c210141ed1c4b0ec7 >>> >>> Since we DISALLOWED venus-decoder and venus-encoder DT nodes, what did >>> Bryan do? Squeezed via driver code fake disallowed nodes and even gave >>> them compatibles not looking like compatibles, so any regex won't work. >>> >>> This power sequencing work here has the same problem of sneaking ABI, >>> which I pointed out here: >>> https://lore.kernel.org/all/9cc5af16-d95e-4f10-8b4a-5e29c136079c@kernel.org/ >>> >>> Look at above patch - nothing documents that ABI. The same as Bryan's >>> fake venus-decoder and encore (not only fake but actually rejected). And >>> to avoid ABI-check tools (or incoming tools), this power sequencing code >>> does not even call a "compatible" a "compatible". No, it calls it >>> "driver_data" nicely avoiding detection. >>> >>> This is terrible practice and I feel like allowing this patch is silent >>> acknowledgment or agreement of such practice. >>> >>> It's about basic ABI principles - if you have DT ABI, it must be both >>> clear in the drivers code and in DT bindings, instead of obfuscated >>> calling a compatible driver data. If you don't, then this is not DT ABI >>> and you are not allowed to use OF code to instantiate drivers. Use SW >>> nodes or KHO-style whatever else is there. >>> >> >> I did propose using SW nodes initially, but then it got changed to > > If I remember previous discussions, SW nodes can be used to provide > additional information about the existing devices. They should not be > used for matching. Yeah, matching is via standard driver name for example like MFD is doing for platform bus. This is not that different than MFD. Best regards, Krzysztof