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Wed, 22 Nov 2023 10:56:53 -0800 (PST) Received: from [192.168.1.20] ([178.197.218.100]) by smtp.gmail.com with ESMTPSA id n28-20020a05600c3b9c00b0040772934b12sm334465wms.7.2023.11.22.10.56.51 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 22 Nov 2023 10:56:53 -0800 (PST) Message-ID: <0321dad4-e94c-4eb8-96ae-4eaae62b3b29@linaro.org> Date: Wed, 22 Nov 2023 19:56:50 +0100 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 V2 1/2] dt-bindings: serial: add Broadcom's BCMBCA family High Speed UART Content-Language: en-US From: Krzysztof Kozlowski To: William Zhang , =?UTF-8?B?UmFmYcWCIE1pxYJlY2tp?= , Florian Fainelli , Anand Gore , Kursad Oney , Rob Herring , Krzysztof Kozlowski , Conor Dooley Cc: Greg Kroah-Hartman , Jiri Slaby , Andre Przywara , Alexandre TORGUE , Neil Armstrong , linux-serial@vger.kernel.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, bcm-kernel-feedback-list@broadcom.com, =?UTF-8?B?UmFmYcWCIE1pxYJlY2tp?= References: <20231122144208.21114-1-zajec5@gmail.com> <66c4b54b-7631-484a-9f7d-31542284e620@linaro.org> <08fcb328-fe4b-40c7-a01e-8a0b527b1c71@gmail.com> <758114a7-0b18-44e8-b3d8-b5aabd244279@linaro.org> <57a77c9d-684e-4f5e-977a-4586e15f7c3e@gmail.com> <141deca9-6017-4e3f-a237-8dacc67662de@linaro.org> <03ad42c0-1648-43e1-bbd0-9ed02bdf4073@gmail.com> <525384ca-f84e-471c-bc82-0029db6ccb77@linaro.org> Autocrypt: addr=krzysztof.kozlowski@linaro.org; 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charset=UTF-8 Content-Transfer-Encoding: 8bit On 22/11/2023 19:46, Krzysztof Kozlowski wrote: > On 22/11/2023 19:39, William Zhang wrote: >> Hi, >> >> On 11/22/2023 07:52 AM, Rafał Miłecki wrote: >>> On 22.11.2023 16:50, Krzysztof Kozlowski wrote: >>>> On 22/11/2023 16:49, Rafał Miłecki wrote: >>>>>>> For example a year ago I added binding for BCMBCA SoC timer without >>>>>>> actual driver, see e112f2de151b ("dt-bindings: timer: Add Broadcom's >>>>>>> BCMBCA timers"). >>>>>>> >>>>>>> I'm not sure if we're going to agree on this, but personally I like >>>>>>> describing hardware as much as I can. So it's well documented / >>>>>>> understood and people may eventually write drivers for it. Maybe it's >>>>>>> partially because I come from Broadcom's world that isn't well known >>>>>>> for upstream efforts in general. >>>>>> >>>>>> The problem is that "brcm,bcmbca-hs-uart" is not describing >>>>>> hardware. It >>>>>> is saying that all these devices have similar (compatible) programming >>>>>> model, so the OS can use just one compatible. This goes away from pure >>>>>> hardware description into interpretation. >>>>>> >> It is the same hardware IP block used in bcmbca SoCs. To me, it >> perfectly describe the hardware IP block and it does not need fallback >> because there is no fallback. We did that for SPI controller although >> it has two revisions of that IP block so we have brcm,bcmbca-hsspi-v1.0 >> and 1.1 >> >>>>>> Rob already commented on such non-SoC compatibles multiple times. I do >>>>>> not see any reason here to not use specific compatible as fallback. >>>>> >> Sorry I missed Rob's comments. If we have any new rule or notes about >> this, I would like to check it out. >> >>>>> Do I get it right we should rather have some base specific compatible >>>>> like: "brcm,bcm63138-hs-uart" and then if anything use fallback to it >>>>> like: "brcm,bcm4908-hs-uart", "brcm,bcm63138-hs-uart"; ? >>>> >>>> Yes, or the other way around, depends which is probably the oldest. >> If we absolutely can not use bcmbca-hs-uart, I would suggest to use > > We can, but I am surprised that you want without any driver. What's the > point of generic compatible? > >> bcm63xx-hs-uart to be more soc specific and in fact the oldest SoC have > > What is xx? Wildcard? I mean... ehhh... OK, it's not worth my time. Neither Rafał's. Reviewed-by: Krzysztof Kozlowski I can go to Embedded OSS every year and give the same speech every year and still people will on: 1. insist on generic fallback compatible, 2. wildcards 3. families I will keep this email and use it to justify the same, third speech next year. Which won't be listened to, so I will go in 2025 fourth time. :) Best regards, Krzysztof