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([2600:1700:e321:62f0:329c:23ff:fee3:9d7c]) by smtp.gmail.com with ESMTPSA id f11-20020a4ae60b000000b0035eb4e5a6bdsm3723135oot.19.2022.05.02.09.16.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 02 May 2022 09:16:24 -0700 (PDT) Sender: Guenter Roeck Message-ID: <25e2dc90-ab01-ab19-ffde-1b709dbebad4@roeck-us.net> Date: Mon, 2 May 2022 09:16:23 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.8.1 Subject: Re: [PATCH v2] hwmon: (tmp401) Add of_match_table Content-Language: en-US To: Vincent Whitchurch Cc: Camel Guo , Jean Delvare , "linux-hwmon@vger.kernel.org" , kernel , "linux-kernel@vger.kernel.org" References: <20220502091942.1083067-1-camel.guo@axis.com> <20220502145800.GA21695@axis.com> From: Guenter Roeck In-Reply-To: <20220502145800.GA21695@axis.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/2/22 07:58, Vincent Whitchurch wrote: > On Mon, May 02, 2022 at 03:57:50PM +0200, Guenter Roeck wrote: >> On 5/2/22 02:19, Camel Guo wrote: >>> When tmp401 is built as kernel module, it won't be automatically loaded >>> even through there is a device node in the devicetree. e.g: >>> i2c { >>> #address-cells = <1>; >>> #size-cells = <0>; >>> >>> sensor@4c { >>> compatible = "ti,tmp401"; >>> reg = <0x4c>; >>> }; >>> }; >>> In order to make sure it is loaded automatically, this commit adds >>> of_match_table for tmp401. >>> >> >> As mentioned before, historically i2c devices would instantiate based >> on the i2c match table. You are claiming that this is no longer the case. > > Note that while the commit message in the first version of the patch did > wrongly claim that probe would not work without the of_match_table, this > corrected description in v2 does mention the actual problem: that the > module will not be automatically loaded without the of_match_table. (If > the module is loaded manually or the driver is built-in to the kernel, > there is no problem.) > No, it doesn't. None of the information you provided below is mentioned in the description, but is essential to understand your patch and the reason for it. > See commit 72fc64c68decf119466 ("hwmon: (tmp103) Add OF device ID > table") or commit 98b16a09861aa85d6 ("hwmon: (max31785) Add OF device ID > table") for similar changes to other hwmon drivers. > Those commits provide a valid and acceptable explanation. > The potential future change mentioned in the commit messages of > 72fc64c68decf119466 and 98b16a09861aa85d6 happened in commit > af503716ac1444db61d80 ("i2c: core: report OF style module alias for > devices registered via OF"). The commit message of > af503716ac1444db61d80 has a lot of details about the change being made, > and while it says that all in-tree drivers had been converted, it looks > like some of them, like tmp401, were missed. > And this is the missing link. If you provide that information in the commit log I have no problems. Please also provide a Fixes: tag. Fixes: af503716ac14 ("i2c: core: report OF style module alias for devices registered via OF") Thanks, Guenter >> The above is no evidence; that would require a log output on an affected >> system showing that the sensors are not or no longer longer instantiated. > > A log would simply show nothing happening so that's probably not going > to be that useful, but here is what the modaliases look like. As you > can see, the modalias of the device in sysfs does not match any of the > alias patterns of the module without this patch: > > $ cat /sys/bus/i2c/devices/4-004c/modalias > of:Ntemperature-sensorTCti,tmp431 > > modinfo without this patch: > > $ modinfo ./modules/lib/modules/5.18.0-rc1/kernel/drivers/hwmon/tmp401.ko > filename: /storage2/femfyra/linux-2.6/.roadtest/./modules/lib/modules/5.18.0-rc1/kernel/drivers/hwmon/tmp401.ko > license: GPL > description: Texas Instruments TMP401 temperature sensor driver > author: Hans de Goede > alias: i2c:tmp435 > alias: i2c:tmp432 > alias: i2c:tmp431 > alias: i2c:tmp411 > alias: i2c:tmp401 > depends: > intree: Y > name: tmp401 > vermagic: 5.18.0-rc1 mod_unload > > modinfo after this patch: > > $ modinfo ./modules/lib/modules/5.18.0-rc1/kernel/drivers/hwmon/tmp401.ko > filename: /storage2/femfyra/linux-2.6/./.roadtest/modules/lib/modules/5.18.0-rc1/kernel/drivers/hwmon/tmp401.ko > license: GPL > description: Texas Instruments TMP401 temperature sensor driver > author: Hans de Goede > alias: i2c:tmp435 > alias: i2c:tmp432 > alias: i2c:tmp431 > alias: i2c:tmp411 > alias: i2c:tmp401 > alias: of:N*T*Cti,tmp435C* > alias: of:N*T*Cti,tmp435 > alias: of:N*T*Cti,tmp432C* > alias: of:N*T*Cti,tmp432 > alias: of:N*T*Cti,tmp431C* > alias: of:N*T*Cti,tmp431 > alias: of:N*T*Cti,tmp411C* > alias: of:N*T*Cti,tmp411 > alias: of:N*T*Cti,tmp401C* > alias: of:N*T*Cti,tmp401 > depends: > intree: Y > name: tmp401 > vermagic: 5.18.0-rc1 mod_unload