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How to read back a fan speed?


HD 4800 lower fan speedHow to troubleshoot fan speed in Linux Mint 17 Cinnamon?Find fan speed and cpu temp in linuxAppliance with USB port for user storage - how to detect/how to allow unsafe unmounts?Fan speed at max in Kali LinuxConfusion regarding #interrupt-cells configuration on PCA9555 expanderHow to control fan speed in Linux running HP laptop?Fan speed is not constantTP Link Wifi dongle connectivity drops after 12 hours on Linux Kernel 2.6How do I rearrange the clock tree to get the clock I need?













0















I am on a custom board using an i.MX6. I am using Yocto (Pyro) to build my kernel (4.14.16).



I am using the generic imx6qdl.dtsi device tree entry for PWM2 to drive the fan and it appears to work fine. The fan has a Tachometer input, which is connected to GPIO2_7. How do I read the fan speed? I have seen device tree blobs for cooling devices, but none of the examples seem to have a tachometer to monitor the fan's speed.






embedded yocto device-tree fan







share|improve this question






















  • Have you checked /sys/class/hwmon/ (and /sys/class/pwm/)? I'm guessing yes, but just want to be sure there isn't an easy solution there.

    – derobert
    4 hours ago
















0















I am on a custom board using an i.MX6. I am using Yocto (Pyro) to build my kernel (4.14.16).



I am using the generic imx6qdl.dtsi device tree entry for PWM2 to drive the fan and it appears to work fine. The fan has a Tachometer input, which is connected to GPIO2_7. How do I read the fan speed? I have seen device tree blobs for cooling devices, but none of the examples seem to have a tachometer to monitor the fan's speed.






embedded yocto device-tree fan







share|improve this question






















  • Have you checked /sys/class/hwmon/ (and /sys/class/pwm/)? I'm guessing yes, but just want to be sure there isn't an easy solution there.

    – derobert
    4 hours ago














0












0








0








I am on a custom board using an i.MX6. I am using Yocto (Pyro) to build my kernel (4.14.16).



I am using the generic imx6qdl.dtsi device tree entry for PWM2 to drive the fan and it appears to work fine. The fan has a Tachometer input, which is connected to GPIO2_7. How do I read the fan speed? I have seen device tree blobs for cooling devices, but none of the examples seem to have a tachometer to monitor the fan's speed.






embedded yocto device-tree fan







share|improve this question














I am on a custom board using an i.MX6. I am using Yocto (Pyro) to build my kernel (4.14.16).



I am using the generic imx6qdl.dtsi device tree entry for PWM2 to drive the fan and it appears to work fine. The fan has a Tachometer input, which is connected to GPIO2_7. How do I read the fan speed? I have seen device tree blobs for cooling devices, but none of the examples seem to have a tachometer to monitor the fan's speed.






embedded yocto device-tree fan




embedded yocto device-tree fan






share|improve this question













share|improve this question











share|improve this question




share|improve this question










asked 2 days ago









EskimoalvaEskimoalva

114




114












  • Have you checked /sys/class/hwmon/ (and /sys/class/pwm/)? I'm guessing yes, but just want to be sure there isn't an easy solution there.

    – derobert
    4 hours ago


















  • Have you checked /sys/class/hwmon/ (and /sys/class/pwm/)? I'm guessing yes, but just want to be sure there isn't an easy solution there.

    – derobert
    4 hours ago

















Have you checked /sys/class/hwmon/ (and /sys/class/pwm/)? I'm guessing yes, but just want to be sure there isn't an easy solution there.

– derobert
4 hours ago






Have you checked /sys/class/hwmon/ (and /sys/class/pwm/)? I'm guessing yes, but just want to be sure there isn't an easy solution there.

– derobert
4 hours ago











1 Answer
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I was unable to find a device tree solution, but found enough code snippets to make an application to read it. Basically I just set up an interrupt on the GPIO and used clock_gettime to measure the period between edges. It requires a lot of filtering, but I am only using it to make sure the fan is running so that is fine.






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    I was unable to find a device tree solution, but found enough code snippets to make an application to read it. Basically I just set up an interrupt on the GPIO and used clock_gettime to measure the period between edges. It requires a lot of filtering, but I am only using it to make sure the fan is running so that is fine.






    share|improve this answer



























      0














      I was unable to find a device tree solution, but found enough code snippets to make an application to read it. Basically I just set up an interrupt on the GPIO and used clock_gettime to measure the period between edges. It requires a lot of filtering, but I am only using it to make sure the fan is running so that is fine.






      share|improve this answer

























        0












        0








        0







        I was unable to find a device tree solution, but found enough code snippets to make an application to read it. Basically I just set up an interrupt on the GPIO and used clock_gettime to measure the period between edges. It requires a lot of filtering, but I am only using it to make sure the fan is running so that is fine.






        share|improve this answer













        I was unable to find a device tree solution, but found enough code snippets to make an application to read it. Basically I just set up an interrupt on the GPIO and used clock_gettime to measure the period between edges. It requires a lot of filtering, but I am only using it to make sure the fan is running so that is fine.







        share|improve this answer












        share|improve this answer



        share|improve this answer










        answered 5 hours ago









        EskimoalvaEskimoalva

        114




        114



























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