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([2600:1700:e321:62f0:da43:aeff:fecc:bfd5]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-24668880bfbsm11992445ad.129.2025.08.22.22.13.31 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 22 Aug 2025 22:13:32 -0700 (PDT) Sender: Guenter Roeck Message-ID: <23146b25-5fac-4392-80d2-4090cb2121aa@roeck-us.net> Date: Fri, 22 Aug 2025 22:13:30 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 4/8] hwmon: Add Apple Silicon SMC hwmon driver To: James Calligeros , Sven Peter , Janne Grunau , Alyssa Rosenzweig , Neal Gompa , Lee Jones , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Alexandre Belloni , Jean Delvare , Dmitry Torokhov Cc: asahi@lists.linux.dev, linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-rtc@vger.kernel.org, linux-hwmon@vger.kernel.org, linux-input@vger.kernel.org References: <20250819-macsmc-subdevs-v1-0-57df6c3e5f19@gmail.com> <20250819-macsmc-subdevs-v1-4-57df6c3e5f19@gmail.com> <56e1f496-a4c7-46a5-bd74-0412c1fd7207@roeck-us.net> <5792171.kQq0lBPeGt@setsuna> Content-Language: en-US From: Guenter Roeck Autocrypt: addr=linux@roeck-us.net; keydata= xsFNBE6H1WcBEACu6jIcw5kZ5dGeJ7E7B2uweQR/4FGxH10/H1O1+ApmcQ9i87XdZQiB9cpN RYHA7RCEK2dh6dDccykQk3bC90xXMPg+O3R+C/SkwcnUak1UZaeK/SwQbq/t0tkMzYDRxfJ7 nyFiKxUehbNF3r9qlJgPqONwX5vJy4/GvDHdddSCxV41P/ejsZ8PykxyJs98UWhF54tGRWFl 7i1xvaDB9lN5WTLRKSO7wICuLiSz5WZHXMkyF4d+/O5ll7yz/o/JxK5vO/sduYDIlFTvBZDh gzaEtNf5tQjsjG4io8E0Yq0ViobLkS2RTNZT8ICq/Jmvl0SpbHRvYwa2DhNsK0YjHFQBB0FX IdhdUEzNefcNcYvqigJpdICoP2e4yJSyflHFO4dr0OrdnGLe1Zi/8Xo/2+M1dSSEt196rXaC kwu2KgIgmkRBb3cp2vIBBIIowU8W3qC1+w+RdMUrZxKGWJ3juwcgveJlzMpMZNyM1jobSXZ0 VHGMNJ3MwXlrEFPXaYJgibcg6brM6wGfX/LBvc/haWw4yO24lT5eitm4UBdIy9pKkKmHHh7s jfZJkB5fWKVdoCv/omy6UyH6ykLOPFugl+hVL2Prf8xrXuZe1CMS7ID9Lc8FaL1ROIN/W8Vk BIsJMaWOhks//7d92Uf3EArDlDShwR2+D+AMon8NULuLBHiEUQARAQABzTJHdWVudGVyIFJv ZWNrIChMaW51eCBhY2NvdW50KSA8bGludXhAcm9lY2stdXMubmV0PsLBgQQTAQIAKwIbAwYL CQgHAwIGFQgCCQoLBBYCAwECHgECF4ACGQEFAmgrMyQFCSbODQkACgkQyx8mb86fmYGcWRAA oRwrk7V8fULqnGGpBIjp7pvR187Yzx+lhMGUHuM5H56TFEqeVwCMLWB2x1YRolYbY4MEFlQg VUFcfeW0OknSr1s6wtrtQm0gdkolM8OcCL9ptTHOg1mmXa4YpW8QJiL0AVtbpE9BroeWGl9v 2TGILPm9mVp+GmMQgkNeCS7Jonq5f5pDUGumAMguWzMFEg+Imt9wr2YA7aGen7KPSqJeQPpj onPKhu7O/KJKkuC50ylxizHzmGx+IUSmOZxN950pZUFvVZH9CwhAAl+NYUtcF5ry/uSYG2U7 DCvpzqOryJRemKN63qt1bjF6cltsXwxjKOw6CvdjJYA3n6xCWLuJ6yk6CAy1Ukh545NhgBAs rGGVkl6TUBi0ixL3EF3RWLa9IMDcHN32r7OBhw6vbul8HqyTFZWY2ksTvlTl+qG3zV6AJuzT WdXmbcKN+TdhO5XlxVlbZoCm7ViBj1+PvIFQZCnLAhqSd/DJlhaq8fFXx1dCUPgQDcD+wo65 qulV/NijfU8bzFfEPgYP/3LP+BSAyFs33y/mdP8kbMxSCjnLEhimQMrSSo/To1Gxp5C97fw5 3m1CaMILGKCmfI1B8iA8zd8ib7t1Rg0qCwcAnvsM36SkrID32GfFbv873bNskJCHAISK3Xkz qo7IYZmjk/IJGbsiGzxUhvicwkgKE9r7a1rOwU0ETofVZwEQALlLbQeBDTDbwQYrj0gbx3bq 7kpKABxN2MqeuqGr02DpS9883d/t7ontxasXoEz2GTioevvRmllJlPQERVxM8gQoNg22twF7 pB/zsrIjxkE9heE4wYfN1AyzT+AxgYN6f8hVQ7Nrc9XgZZe+8IkuW/Nf64KzNJXnSH4u6nJM J2+Dt274YoFcXR1nG76Q259mKwzbCukKbd6piL+VsT/qBrLhZe9Ivbjq5WMdkQKnP7gYKCAi pNVJC4enWfivZsYupMd9qn7Uv/oCZDYoBTdMSBUblaLMwlcjnPpOYK5rfHvC4opxl+P/Vzyz 6WC2TLkPtKvYvXmdsI6rnEI4Uucg0Au/Ulg7aqqKhzGPIbVaL+U0Wk82nz6hz+WP2ggTrY1w ZlPlRt8WM9w6WfLf2j+PuGklj37m+KvaOEfLsF1v464dSpy1tQVHhhp8LFTxh/6RWkRIR2uF I4v3Xu/k5D0LhaZHpQ4C+xKsQxpTGuYh2tnRaRL14YMW1dlI3HfeB2gj7Yc8XdHh9vkpPyuT nY/ZsFbnvBtiw7GchKKri2gDhRb2QNNDyBnQn5mRFw7CyuFclAksOdV/sdpQnYlYcRQWOUGY HhQ5eqTRZjm9z+qQe/T0HQpmiPTqQcIaG/edgKVTUjITfA7AJMKLQHgp04Vylb+G6jocnQQX JqvvP09whbqrABEBAAHCwWUEGAECAA8CGwwFAmgrMyQFCSbODQkACgkQyx8mb86fmYHlgg/9 H5JeDmB4jsreE9Bn621wZk7NMzxy9STxiVKSh8Mq4pb+IDu1RU2iLyetCY1TiJlcxnE362kj njrfAdqyPteHM+LU59NtEbGwrfcXdQoh4XdMuPA5ADetPLma3YiRa3VsVkLwpnR7ilgwQw6u dycEaOxQ7LUXCs0JaGVVP25Z2hMkHBwx6BlW6EZLNgzGI2rswSZ7SKcsBd1IRHVf0miwIFYy j/UEfAFNW+tbtKPNn3xZTLs3quQN7GdYLh+J0XxITpBZaFOpwEKV+VS36pSLnNl0T5wm0E/y scPJ0OVY7ly5Vm1nnoH4licaU5Y1nSkFR/j2douI5P7Cj687WuNMC6CcFd6j72kRfxklOqXw zvy+2NEcXyziiLXp84130yxAKXfluax9sZhhrhKT6VrD45S6N3HxJpXQ/RY/EX35neH2/F7B RgSloce2+zWfpELyS1qRkCUTt1tlGV2p+y2BPfXzrHn2vxvbhEn1QpQ6t+85FKN8YEhJEygJ F0WaMvQMNrk9UAUziVcUkLU52NS9SXqpVg8vgrO0JKx97IXFPcNh0DWsSj/0Y8HO/RDkGXYn FDMj7fZSPKyPQPmEHg+W/KzxSSfdgWIHF2QaQ0b2q1wOSec4Rti52ohmNSY+KNIW/zODhugJ np3900V20aS7eD9K8GTU0TGC1pyz6IVJwIE= In-Reply-To: <5792171.kQq0lBPeGt@setsuna> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 8/22/25 20:33, James Calligeros wrote: > Hi Guenter, > > On Wednesday, 20 August 2025 2:02:58 am Australian Eastern Standard Time Guenter Roeck wrote: >> On 8/19/25 04:47, James Calligeros wrote: >>> +/* >>> + * Many sensors report their data as IEEE-754 floats. No other SMC >>> function uses + * them. >>> + */ >>> +static int macsmc_hwmon_read_f32_scaled(struct apple_smc *smc, smc_key >>> key, + int *p, int scale) >>> +{ >>> + u32 fval; >>> + u64 val; >>> + int ret, exp; >>> + >>> + ret = apple_smc_read_u32(smc, key, &fval); >>> + if (ret < 0) >>> + return ret; >>> + >>> + val = ((u64)((fval & FLT_MANT_MASK) | BIT(23))); >>> + exp = ((fval >> 23) & 0xff) - FLT_EXP_BIAS - FLT_MANT_BIAS; >>> + if (scale < 0) { >>> + val <<= 32; >>> + exp -= 32; >>> + val /= -scale; >> >> I am quiter sure that this doesn't compile on 32 bit builds. >> > I don't see why not. We're not doing any 64-bit math on pointers, so we should Odd (and wrong) answer. What do pointers have to do with 64-bit math ? Nothing. val is a 64-bit variable, so "val /= -scale" is a 64-bit math operation. > be safe here. Regardless, this driver depends on MFD_MACSMC, which depends on > ARCH_APPLE, which is an ARM64 platform, so this driver shouldn't be compiled > during a 32-bit build anyway. Right answer. > > >>> + >>> + ret = of_property_read_string(fan_node, "apple,key-id", &now); >>> + if (ret) { >>> + dev_err(dev, "apple,key-id not found in fan node!"); >>> + return -EINVAL; >>> + } >>> + >>> + ret = macsmc_hwmon_parse_key(dev, smc, &fan->now, now); >>> + if (ret) >>> + return ret; >>> + >>> + if (!of_property_read_string(fan_node, "label", &label)) >>> + strscpy_pad(fan->label, label, sizeof(fan->label)); >>> + else >>> + strscpy_pad(fan->label, now, sizeof(fan->label)); >>> + >>> + fan->attrs = HWMON_F_LABEL | HWMON_F_INPUT; >>> + >>> + ret = of_property_read_string(fan_node, "apple,fan-minimum", &min); >>> + if (ret) >>> + dev_warn(dev, "No minimum fan speed key for %s", fan->label); >>> + else { >>> + if (!macsmc_hwmon_parse_key(dev, smc, &fan->min, min)) >>> + fan->attrs |= HWMON_F_MIN; >> >> Above the error from macsmc_hwmon_parse_key() results in an abort, >> here the error is logged in the function and ignored. >> >> Either it is an error or it isn't. Ignoring errors is not acceptable. >> Dumping error messages and ignoring the error is even less acceptable. >> > The only strictly required key for fan speed monitoring is apple,key-id, > which is why it is the only one that causes an early return when parsing > it fails. If we don't have keys in the DT for min, max, target and mode, > then all that means is we can't enable manual fan speed control. I don't > see how making a failure to read these keys non-blocking is unacceptable > in this context. If this is about the dev_err print in parse_key, then > I can just get rid of that and have the parse_key callers do it when it's > actually a blocking error. dev_err -> it is an error. Don't ignore it. If some of the properties are optional, they should be defined as such in the devicetree description, there should be neither an error nor a warning message. Plus, the above should be explained in a comment so future developers do not wonder and don't add error handling. Guenter