From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 A8E381591E8; Tue, 22 Oct 2024 08:23:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729585422; cv=none; b=ntZ/wBxWHq21VKUc4u6zhJk6zyGV7KSCsy2vkVRjWgjIvpPmyst+C9pXg4zCHCF7LVSg0GsUOmE4JOxjK1OT2HjeHP5LktjAC8Qmet+Fj0XF3T7/2yzdcXh4BQ5zV9seAy+HcqYHgKPPk4Uir7Mq0ZtGYRAkOqe3yz5H00D7KNE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729585422; c=relaxed/simple; bh=Mp6oY9iFBjKTrbRDjHpbclWZ0T/5GgrVM/Hw/ucbepw=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=RR/IPlY+/xI9drNU4x7qQD4GlBvs24HREtF9+wrSLJoo8R9nMaQhtsuURF1j01U+T2ZKyAcmhAD31yl8t99LLCLyw1IQl7XGINwpXiyf6mJC69IPgPDappcj122RKKO2OvgmW6KkTVAugKrbyfzWHgROF/MnWqHAfMhVCjeU5Z8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=nUU0Asrs; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="nUU0Asrs" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 91DFFC4CEC3; Tue, 22 Oct 2024 08:23:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1729585422; bh=Mp6oY9iFBjKTrbRDjHpbclWZ0T/5GgrVM/Hw/ucbepw=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=nUU0Asrsy+9MA0eNCLJ3dn6oGfWJIS+YgCp67QoY1sf27OCmwDkpp1cH7Q0Fd2JXG hT1Od70xOpNo7OPFM6CWA+9a5SDtneeY/UdMd2WBSI60eh91lpbwA8+vY/FolGveGt 3D8FWLpfdxFoOr8HLx1xOsPnWGe+8g0xTpos3tOMiEJFMat0PRuujAycP0RZlhRCQk 3skmLHharQoU8CkhM9K4+LX9cKDlCVzrURQVB19MWngkj5PeyTnZ253E+/fPZ1ALK5 5CwRw9oNUhH41h/R8rpawku2KgCj/bZcEY5dulIWqyGwy9miJM672D35WylgCIYPau VUapFZWTBm9LQ== Message-ID: <9c7b0e22-1d15-45a2-a263-9b03348adb45@kernel.org> Date: Tue, 22 Oct 2024 10:23:35 +0200 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/2] dt-bindings: net: bluetooth: nxp: add support for supply and reset To: Marco Felsch Cc: POPESCU Catalin , Sherry Sun , Amitkumar Karwar , Neeraj Sanjay Kale , "marcel@holtmann.org" , "luiz.dentz@gmail.com" , "robh@kernel.org" , "krzk+dt@kernel.org" , "conor+dt@kernel.org" , "p.zabel@pengutronix.de" , "linux-bluetooth@vger.kernel.org" , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" , GEO-CHHER-bsp-development References: <3fa35cd2-e52c-4873-8a7f-db459b016a97@kernel.org> <2b7f61a8-e91a-4b32-be1d-753a19e4d81f@leica-geosystems.com> <0d460226-4ea7-4a9b-a119-468343727996@kernel.org> <20241021064129.trchqa2oickna7pc@pengutronix.de> <20241021102558.rfnz7nxcg5knibxs@pengutronix.de> <20241022071208.lgk2rpl2c2qpytfa@pengutronix.de> <66d33097-37ed-4e89-a356-285eda743a5c@kernel.org> <20241022081304.d2tpnn4eyf3adxg2@pengutronix.de> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 22/10/2024 10:13, Marco Felsch wrote: > On 24-10-22, Krzysztof Kozlowski wrote: >> On 22/10/2024 09:30, Krzysztof Kozlowski wrote: >>> On 22/10/2024 09:12, Marco Felsch wrote: >>>> On 24-10-22, Krzysztof Kozlowski wrote: >>>>> On 21/10/2024 12:25, Marco Felsch wrote: >>>>>> On 24-10-21, Krzysztof Kozlowski wrote: >>>>>>> On 21/10/2024 08:41, Marco Felsch wrote: >>>>>>>> On 24-10-07, Krzysztof Kozlowski wrote: >>>> >>>> ... >>>> >>>>>>>>> Based on earlier message: >>>>>>>>> >>>>>>>>> "For NXP WIFI/BT chip, WIFI and BT share the one PDn pin, which means >>>>>>>>> that both wifi and BT controller will be powered on and off at the same >>>>>>>>> time." >>>>>>>>> >>>>>>>>> but maybe that's not needed. No clue, I don't know the hardware. But be >>>>>>>>> carefully what you write in the bindings, because then it will be ABI. >>>>>>>> >>>>>>>> We noticed the new power-sequencing infrastructure which is part of 6.11 >>>>>>>> too but I don't think that this patch is wrong. The DT ABI won't break >>>>>>>> if we switch to the power-sequencing later on since the "reset-gpios" >>>>>>>> are not marked as required. So it is up to the driver to handle it >>>>>>>> either via a separate power-sequence driver or via "power-supply" and >>>>>>>> "reset-gpios" directly. >>>>>>> >>>>>>> That's not the point. We expect correct hardware description. If you say >>>>>>> now it has "reset-gpios" but later say "actually no, because it has >>>>>>> PMU", I respond: no. Describe the hardware, not current Linux. >>>>>> >>>>>> I know that DT abstracts the HW. That said I don't see the problem with >>>>>> this patch. The HW is abstracted just fine: >>>>>> >>>>>> shared PDn -> reset-gpios >>>>>> shared power-supply -> vcc-supply >>>>>> >>>>>> Right now the DT ABI for the BT part is incomplete since it assume a >>>>>> running WLAN part or some hog-gpios to pull the device out-of-reset >>>>>> which is addressed by this patchset. >>>>>> >>>>>> Making use of the new power-sequencing fw is a Linux detail and I don't >>>>>> see why the DT can't be extended later on. We always extend the DT if >>>>>> something is missing or if we found a better way to handle devices. >>>>> >>>>> Sure, although I am not really confident that you understand the >>>>> implications - you will not be able to switch to proper power-sequencing >>>>> with above bindings, because it will not be just possible without >>>>> breaking the ABI or changing hardware description (which you say it is >>>>> "fine", so complete/done). I am fine with it, just mind the implications. >>>> >>>> Sorry can you please share your concerns? I don't get the point yet why >>>> we do break the DT ABI if we are going from >>> >>> Not necessarily breaking ABI, but changing the description. >>>> >>>> bt { >>>> reset-gpios = <&gpio 4 0>; >>>> vcc-supply = <&supply>; >>>> }; >>>> >>>> to >>>> >>>> bt { >>>> vcc-supply = <&pmu_supply>; >>> >>> ...because you just removed reset-gpios which is a property of this device. > > An optional property. That beeing said, dropping the *-gpios was the > solution for the Qualcomm DTS as well: > > bd37ce2eeb84 ("arm64: dts: qcom: qrb5165-rb5: add the Wifi node") True, the difference is I think that we came with proper PMU model only recently while above device is supported for few years. This is not the case here: you can choose now hardware description which will be both accurate and solve power sequencing issues. > >>>> }; >>>> >>>> or: >>>> >>>> bt { >>>> pmu = <&pmu>; >> >> Ah, and I forgot here: this also might not be correct, because if you >> have PMU, then the PMU consumes VCC, not the Bluetooth. Therefore both >> of above two solutions might be inaccurate description if you decide to >> go with PMU. >> >>>> }; >>>> >>>> Of course the driver need to support all 2/3 cases due to backward >>>> compatibility but from DT pov I don't see any breakage since we already >>>> need to define the power handling properties (gpio & supply) as >>>> optional. >>> >>> Either existing binding is complete or not. Not half-done. > > As I remember DT ABI must be backward compatible. I understand this as > followed: In our current use-case the dt-bindings don't describe any > required hw resource so we need to mark them as optional to be backward > compatible. > > Regarding your above comment: "complete or not. Not half-done". Do you > see the current dt-bindings for this particular device as complete or > not? In other words can we mark the reset-gpios and vcc-supply > properties as required albeit this would break the DT ABI since all > current users don't specify it? It is not about required property. Does this device has reset lines or not? If yes, then please do not come in 2 years removing it from DTS. Because this breaks all of DTS users. > >>>> That beeing said I don't see the need for a PMU driver for this WLAN/BT >>>> combi chip which is way simpler than the Qualcomm one from Bartosz. Also >>>> there is physically no PMU device which powers the chip unlike the >>>> Qualcomm one. I'm not sure if you would accept virtual PMU devices. >>> >>> Virtual PMU, of course not. I would like to have complete hardware >>> description, not something which matches your current driver model. > > Okay so PMU is no option and we don't have to consider this idea any > longer. So reset-gpios and vcc-supply it is :) and I don't expect this > to change. Ack. Best regards, Krzysztof