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Tue, 20 Oct 2026 08:03:03 +0000 (GMT) Received: from epcas5p3.samsung.com (unknown [182.195.38.89]) by epsnrtp04.localdomain (Postfix) with ESMTP id 4j84fG3qvSz6B9mF; Tue, 20 Oct 2026 08:03:02 +0000 (GMT) Received: from epsmtip2.samsung.com (unknown [182.195.34.31]) by epcas5p2.samsung.com (KnoxPortal) with ESMTPA id 20261020080302epcas5p2140954a64a9a8db0f7b802611431eed3~gLiOS_PnJ2967129671epcas5p2u; Tue, 20 Oct 2026 08:03:02 +0000 (GMT) Received: from [107.122.5.126] (unknown [107.122.5.126]) by epsmtip2.samsung.com (KnoxPortal) with ESMTPA id 20261020080259epsmtip225517e3ffa9b53b64dade8aaa8df77cb~gLiLgSsR62884528845epsmtip2g; Tue, 20 Oct 2026 08:02:58 +0000 (GMT) Message-ID: <6643fece-aa39-42e6-8cd6-5264f15e12ff@samsung.com> Date: Tue, 20 Oct 2026 13:32:58 +0530 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 2/3] dt-bindings: usb: Introduce samsung,snps-dwc3 From: Selvarasu Ganesan To: Krzysztof Kozlowski Cc: peter.griffin@linaro.org, alim.akhtar@samsung.com, gregkh@linuxfoundation.org, robh@kernel.org, conor+dt@kernel.org, Thinh.Nguyen@synopsys.com, mani@kernel.org, linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org, linux-usb@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, jh0801.jung@samsung.com, h10.kim@samsung.com, dh10.jung@samsung.com, akash.m5@samsung.com, hongpooh.kim@samsung.com, eomji.oh@samsung.com, shijie.cai@samsung.com, muhammed.ali@samsung.com, thiagu.r@samsung.com Content-Language: en-US In-Reply-To: Content-Transfer-Encoding: 8bit X-CMS-MailID: 20261020080302epcas5p2140954a64a9a8db0f7b802611431eed3 X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" CMS-TYPE: 105P cpgsPolicy: CPGSC10-542,Y X-CFilter-Loop: Reflected X-CMS-RootMailID: 20260916122354epcas5p401fd6470d6cef75951af732b03aa5970 References: <20260916122229.2604003-1-selvarasu.g@samsung.com> <20260916122229.2604003-3-selvarasu.g@samsung.com> <20260918-burgundy-marmoset-of-focus-c9b9a7@quoll> <7fbcf497-a166-45d6-844d-faaece6f581c@kernel.org> On 9/21/2026 12:26 PM, Selvarasu Ganesan wrote: > > On 9/18/2026 7:16 PM, Krzysztof Kozlowski wrote: >> On 18/09/2026 15:36, Selvarasu Ganesan wrote: >>> On 9/18/2026 3:24 PM, Krzysztof Kozlowski wrote: >>>> On Wed, Sep 16, 2026 at 05:52:28PM +0530, Selvarasu Ganesan wrote: >>>>> +maintainers: >>>>> +  - Krzysztof Kozlowski >>>>> +  - Selvarasu Ganesan >>>>> + >>>>> +description: >>>>> +  Describes the DWC3 USB controller block implemented on Samsung >>>>> Exynos SoCs. >>>>> + >>>>> +select: >>>>> +  properties: >>>>> +    compatible: >>>>> +      contains: >>>>> +        const: samsung,snps-dwc3 >>>>> +  required: >>>>> +    - compatible >>>> This select is not needed. >>>> >>>>> + >>>>> +properties: >>>>> +  compatible: >>>>> +    items: >>>>> +      - enum: >>>>> +          - samsung,exynos8855-dwc3 >>>>> +      - const: samsung,snps-dwc3 >>>> And this fallback is not really accurate. Samsung does not have snps >>>> device, because snps is a vendor. Anyway, generic fallbacks should go >>>> away, drop, so you are left with samsung,exynos8855-dwc3 only. >>> Hi Krzysztof, >>> >>> Thanks for your review comments. >>> And We apologize for our repeated below explanation, but we wanted to >>> ensure our intentions were clear for each point to avoid any >>> misunderstanding. >>> >>> The original intent of the generic fallback was to support existing >>> Exynos dwc3 bindings from a parent/child representation from >> How does it support existing bindings? I don't understand. There is no >> such fallback in existing bindings. > > > Sorry for the misunderstanding, Yes there is no such a fallback in > existing bindings. > > Our intention was to use new proposed generic fallback compatible > string that will support USB dwc3 flatted node for all Samsung soc > when those are migrated in the future without adding SoC specific > compatible string in driver. > > Agreed, Here using generic fallback name (samsung,snps-dwc3 as a > reference of qcom,snps-dwc3) is incorrect as snps is vendor not a device. > > As per DTS101 slide , Now we clear that the future Exynos SoCs could > use  samsung,exynos8855-dwc3 as a fallback when they are compatible > with the Exynos8855 hardware definition, rather than introducing a > generic samsung,snps-dwc3 fallback. The dedicated compatible would > still describe any SoC specific differences, such as clocks. > > And Understood that we were mixing the current Exynos8855 binding with > the longer term migration plan for the existing Exynos SoCs and future > SoCs. > > We will drop the generic fallback and use SoC specific compatible > samsung,exynos8855-dwc3 (vendor,device), following > samsung,exynos-dwc3.yaml as the reference. > > Regarding the binding filename, if the flattened representation is > expected to support multiple Exynos SoCs where there is only > differences in clock in the future, similar to how > samsung,exynos-dwc3.yaml covers multiple SoCs with the legacy (parent > and child) node representation, should we use a common binding > filename for the flattened representation instead of a SoC specific > name like samsung,exynos8855-dwc3.yaml. > For example, >     samsung,exynos-dwc3-flattened.yaml. HI Krzysztof, I am writing to kindly follow up on my previous inquiry regarding the binding filename for the flattened representation. To recap, I would like to know if we should use a common binding filename, such as samsung,exynos-dwc3-flattened.yaml, instead of SoC specific names (e.g., samsung,exynos8855-dwc3.yaml). This would be consistent with how samsung,exynos-dwc3.yaml covers multiple SoCs in the legacy representation, especially if we expect to support multiple Exynos SoCs with only clock differences in the future. I would appreciate your guidance or suggestions on the preferred naming convention for this implementation. Thanks, Selva > > >> >>> (samsung,exynos-dwc3.yaml), and upcoming SoCs (Exynos 8865, 9955, and >>> 9965) can use this flattened representation without requiring a unique >>> compatible string for every project in the dwc3-generic-plat driver >> I did not forbid you to use fallbacks, so I do not understand why you >> would need unique compatible for every device in the driver. > > > The intention was to avoid adding separate compatible entries to > dwc3_generic_of_match[] for each Exynos SoC. > > We understand that adding SoC specific compatibles is the correct > approach, as follow in samsung,exynos-dwc3.yaml. > > >> >> This is already heavily documented and explained in beginners docs. >> Please read writing bindings docs and maybe also DTS101 slides. I even >> gave the talk DTS101 two months ago in your timezone... > > Thanks for pointing out the DTS101 slids, and we referred again the > binding documentation including DTS101 slids for further clarification > on the using of fallback. > >> >> >>> of_match_table. We referred to qcom,snps-dwc3 as a helpful reference >>> for >>> this approach. >> When people argue with me, they use more often poor examples as >> reference, not the good ones. Interesting pattern. >> >> And why you did not take the proper example you even mentioned here - >> Documentation/devicetree/bindings/usb/samsung,exynos-dwc3.yaml - as >> reference? >> >> Anyway, existing bug is not a reason to add new bug, don't you think? > > Agreed and As we mentioned in above comment, we will use the existing > samsung,exynos-dwc3.yaml as the reference for the Samsung binding and > drop the qcom,snps-dwc3 reference. > >> >> >>> As seen in samsung,exynos-dwc3.yaml, our existing bindings already >>> support multiple SoCs with diverse clock requirements within a single >>> file. Similarly, we plan to use a single flattened Samsung binding to >>> manage these diverse clock requirements. for different SoCs. >>> >>> Regarding the migration for current and future SoCs, would you prefer, >> I do not understand how any of this is relevant to my review comment. >> >>> Option A: A single flattened binding file using a common fallback >>> compatible string (instead of samsung,snps-dwc3) to minimize >>> of_match_table entries, and if/then constraints to handle diverse clock >>> requirements. >>> Option B: Separate binding files for each individual SoCs. >>> >>> Could you please let us know your preferred approach? Once >>> confirmed, we >>> will address your other review comments based on the selected approach. >> You do not have other bindings. You have one device. If you have more, >> then post more. We are not making reviews based on imaginary future >> things. > > Understood. As mentioned above, we are mixing the current Exynos8855 > binding with the longer term migration plan and will keep this binding > focused on Exynos8855 only and handle other SoCs when they are > actually migrated. > > Thanks, > Selva > > >> >> Best regards, >> Krzysztof