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Message-ID: <cfd9cbc6-5f66-4929-9afb-3a572e93e8ae@linaro.org>
Date:   Wed, 6 Dec 2023 18:35:53 +0100
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Subject: Re: [PATCH 2/6] dt-bindings: pwm: samsung: add specific compatible
 for Tesla FSD
Content-Language: en-US
To:     Thierry Reding <thierry.reding@gmail.com>
Cc:     Andi Shyti <andi.shyti@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Conor Dooley <conor+dt@kernel.org>,
        Alim Akhtar <alim.akhtar@samsung.com>,
        =?UTF-8?Q?Uwe_Kleine-K=C3=B6nig?= <u.kleine-koenig@pengutronix.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jiri Slaby <jirislaby@kernel.org>,
        Wim Van Sebroeck <wim@linux-watchdog.org>,
        Guenter Roeck <linux@roeck-us.net>, linux-fsd@tesla.com,
        linux-i2c@vger.kernel.org, devicetree@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-samsung-soc@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-pwm@vger.kernel.org, linux-serial@vger.kernel.org,
        linux-watchdog@vger.kernel.org
References: <20231205092229.19135-1-krzysztof.kozlowski@linaro.org>
 <20231205092229.19135-3-krzysztof.kozlowski@linaro.org>
 <ZXCeWmEO3PJiK0m5@orome.fritz.box>
From:   Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
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In-Reply-To: <ZXCeWmEO3PJiK0m5@orome.fritz.box>
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Precedence: bulk

On 06/12/2023 17:16, Thierry Reding wrote:
> On Tue, Dec 05, 2023 at 10:22:25AM +0100, Krzysztof Kozlowski wrote:
>> Tesla FSD is a derivative of Samsung Exynos SoC, thus just like the
>> others it reuses several devices from older designs.  Historically we
>> kept the old (block's) compatible only.  This works fine and there is no
>> bug here, however guidelines expressed in
>> Documentation/devicetree/bindings/writing-bindings.rst state that:
>> 1. Compatibles should be specific.
>> 2. We should add new compatibles in case of bugs or features.
>>
>> Add Tesla FSD compatible specific to be used with an existing fallback.
>>
>> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
>>
>> ---
>>
>> I propose to take the patch through Samsung SoC (me). See cover letter
>> for explanation.
>> ---
>>  Documentation/devicetree/bindings/pwm/pwm-samsung.yaml | 1 +
>>  1 file changed, 1 insertion(+)
> 
> You point to the guidelines that say we should have specific compatible> strings, but then the string that you add seems very generic. Now, I'm
> obviously not an expert on Tesla hardware, but just FSD seems to be
> quite generic according to the internet. It seems like the chip derived
> from Samsung used to be known as AP3/HW3, but there's now also AP4/HW4,
> so I wonder if those differ in some way and if these shouldn't include
> some sort of version/generation number.

That's the compatible chosen that time for entire platform, as a
consensus, for all SoC components. Thus the PWM compatible is as
specific as it can get.

Best regards,
Krzysztof