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([2600:1700:e321:62f0:da43:aeff:fecc:bfd5]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-3286f7be607sm17361289eec.10.2026.08.29.10.05.14 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 29 Aug 2026 10:05:15 -0700 (PDT) Sender: Guenter Roeck Message-ID: <89971e52-a88c-49bd-a0a6-17e48820974d@roeck-us.net> Date: Sat, 29 Aug 2026 10:05:13 -0700 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 v3 2/2] hwmon: (starfive-fan-tach) Add fan tach driver for StarFive JHB100 To: sashiko-reviews@lists.linux.dev, Changhuang Liang Cc: devicetree@vger.kernel.org, linux-hwmon@vger.kernel.org, robh@kernel.org, conor+dt@kernel.org References: <20260824030234.9321-1-changhuang.liang@starfivetech.com> <20260824030234.9321-3-changhuang.liang@starfivetech.com> <20260824032750.0749D1F000E9@smtp.kernel.org> 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: <20260824032750.0749D1F000E9@smtp.kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 8/23/26 20:27, sashiko-bot@kernel.org wrote: > Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider: > - [Medium] Missing explicit initialization of interrupt and channel enable registers during probe > -- > > --- Patch [2]: [PATCH v3 2/2] hwmon: (starfive-fan-tach) Add fan tach driver for StarFive JHB100 --- > commit ea266a681c03cda9faa04f08b171c20f1e003841 > Author: Changhuang Liang > > hwmon: (starfive-fan-tach) Add fan tach driver for StarFive JHB100 > > This commit adds a new driver for the fan tachometer controller found on the > StarFive JHB100 SoC. It provides support for up to 16 independent fan > tachometer inputs and reports fan speed in RPM through the hwmon sysfs > interface. > >> diff --git a/drivers/hwmon/starfive-fan-tach.c b/drivers/hwmon/starfive-fan-tach.c >> new file mode 100644 >> index 0000000000000..7f56ecc87c1c8 >> --- /dev/null >> +++ b/drivers/hwmon/starfive-fan-tach.c > [ ... ] >> +static int starfive_fan_tach_probe(struct platform_device *pdev) >> +{ > [ ... ] >> + ret = reset_control_deassert(priv->rst); >> + if (ret) { >> + clk_disable_unprepare(priv->clk); >> + return dev_err_probe(dev, ret, "Failed to deassert reset\n"); >> + } >> + >> + ret = devm_add_action_or_reset(dev, starfive_fan_tach_disable, priv); >> + if (ret) >> + return ret; >> + >> + writel(STARFIVE_FAN_TACH_STALL_INT_MASK | STARFIVE_FAN_TACH_SLOW_INT_MASK, >> + priv->regs + STARFIVE_FAN_TACH_STATUS); >> + writel(priv->clk_rate / STARFIVE_FAN_DEFAULT_MEASURE_RATIO, >> + priv->regs + STARFIVE_FAN_TACH_MEASURE_TIME); > > [Severity: Medium] > Could this code be susceptible to an interrupt storm if the bootloader leaves > the FAN-TACH controller enabled with unmasked interrupts? > > Since the driver only deasserts the reset line during probe (and does not > assert it first), the hardware state might be retained from before the kernel > booted. Any read-modify-write operations on STARFIVE_FAN_TACH_INT_EN and > STARFIVE_FAN_TACH_CH_EN later in the driver would then preserve these stray > bits. > > Once devm_request_irq() is called, any unexpected unmasked interrupts will > trigger. If the interrupt condition is continuous (e.g., a disconnected or > stalled fan), the ISR will clear the STATUS bit, but the hardware will > immediately re-assert it. Because the driver's ISR does not mask unexpected > interrupts in INT_EN (it only signals completions if armed_stall or > armed_slow are set), wouldn't this lead to an interrupt storm? > > Should the interrupt and channel enable registers be explicitly initialized > to 0 before requesting the IRQ to ensure a known safe hardware state? > Please either implement as suggested or explain why it is not needed. In that case, please add a comment into the code explaining the reason. Thanks, Guenter