From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 6BB3C15D5C8 for ; Wed, 28 Feb 2024 16:09:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709136573; cv=none; b=IcIcUM5osViOthBeF02YVsdKeaRti/Q/9lS23m8gmAzbX33EP6qN9CiuCTG9A75mGctHodd0LrOdHLggsHXvxBmomwBppHGQFAa1MRBovCuofuhP9O4oS57/FzgAG3rGhLe64esufsgGu72XkbSJWpYRG7QdTsPyUh65eWANH5E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709136573; c=relaxed/simple; bh=gVTFIUnyBhfVXZUzI+rgslpMPypmByyudLTimO3ifVQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Spy9UNWBB5YnEDCJC3dAoZlViVjtqwEVIHcnmawgyiIEjW8laeGts5Nkym/jPSMmpEugSdGPJGD81tczmxk+Nj/NVNNXRV5Dg0BGfbR9xXId1tpwBd72ns0F7AxCcpNBwfsUWGtJCNFBHHHH+1+YqRsBDlmSrNdUstbInTS8nGE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id BE03EC15; Wed, 28 Feb 2024 08:10:09 -0800 (PST) Received: from bogus (unknown [10.57.94.75]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id AC5A33F762; Wed, 28 Feb 2024 08:09:28 -0800 (PST) Date: Wed, 28 Feb 2024 16:09:25 +0000 From: Sudeep Holla To: Krzysztof Kozlowski Cc: Ulf Hansson , Nikunj Kela , Sudeep Holla , Manivannan Sadhasivam , krzysztof.kozlowski+dt@linaro.org, Vincent Guittot , robh+dt@kernel.org, conor+dt@kernel.org, devicetree@vger.kernel.org, "Prasad Sodagudi (QUIC)" , srinivas.kandagatla@linaro.org Subject: Re: DT Query on "New Compatible vs New Property" Message-ID: <20240228160925.fcitj2yz7hisidsl@bogus> References: <7910de2d-6184-4f78-a286-d2e6e50c7a36@quicinc.com> <16db3da8-dfdd-4e06-b348-33e9197fe18d@quicinc.com> <32092ee9-018f-4cfb-950e-26c69764f35a@quicinc.com> <94a62a78-961a-4286-804c-fc0b9098b8a1@quicinc.com> <20240228140239.gkzcytw6cmb4opja@bogus> <799268ac-7ffb-4b99-b037-d5bb93d37f13@linaro.org> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <799268ac-7ffb-4b99-b037-d5bb93d37f13@linaro.org> On Wed, Feb 28, 2024 at 03:20:44PM +0100, Krzysztof Kozlowski wrote: > On 28/02/2024 15:02, Sudeep Holla wrote: > > On Wed, Feb 28, 2024 at 02:27:30PM +0100, Ulf Hansson wrote: > >> On Mon, 26 Feb 2024 at 15:24, Nikunj Kela wrote: > >>> > >>> Hi Sudeep, > >>> > >>> I would like to conclude on this thread. I was discussing this with Ulf. > >>> He thinks that using the domain names to identify if platform is > >>> abstracting clocks etc. are not scalable and sufficient. Instead he > >>> thinks that the change in the interface to OS(and FW) is a good > >>> candidate for a new compatible(even though HW is same). Even for SCMI, > >>> we do change phandle in DT to SCMI protocol phandle so that is like a > >>> different platform altogether. Could you please let me know if you still > >>> think that using a different compatible in this case is not warranted. > >> > >> My apologies for joining this discussion at this late state. Yet, I > >> just wanted to confirm what Nikunj said above. > >> > >> In the end we are indeed talking about adding a new platform, as > >> changing the FW interface from a QCOM proprietary one into SCMI, > >> simply requires updates to a DTS file(s) that is platform specific. > >> > > > > The way I read this sounds like all this are platform specific and need > > new compatible. > > > >> That said, it also seems reasonable to me to use a compatible string, > >> to allow us to describe the update of HW for various affected devices. > >> > > > > While I agree with the above statement, it depends on what you refer as > > update of HW above. It is all Qcom specific and there is so much turn > > between SoCs that this shouldn't matter but I would like to take example > > and describe what I initially mentioned/argued against. > > > > Lets us assume 2 SoCs: A and B. A is old and didn't use SCMI while B is > > new and migrated to use SCMI. Now let us assume both A and B SoCs have > > exact same version/revision of an IP: X. Now just because B uses SCMI, > > should X have one compatible to be used in A and another in B. That > > doesn't sound right IMO. > > That's trivial to answer, because these are different SoCs. Compatibles > are SoC specific and every SoC-IP-block needs its compatible. Rob was > repeating this many times that versioned compatibles are discouraged. OK I may have confused or derailed the discussion with the mention of "exact same version/revision" of X. This is not related versioned compatibles. Let me try to explain it with some real example. If you look at all the users of "arm,coresight-tpiu", they all have same compatible on all the platforms irrespective of the clock/reset/voltage/power domain providers on these platforms. E.g. on juno it is based on SCMI while on qcom-msm8974/apq8064 or hi3660/hi6220 it is platform specific clock/power domain providers. However all these platform have the same compatible "arm,coresight-tpiu". That was the point I was trying to make and not related to versioned compatible for different versions on an IP. -- Regards, Sudeep