642 lines
16 KiB
ReStructuredText
642 lines
16 KiB
ReStructuredText
Kernel driver lm90
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==================
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Supported chips:
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* National Semiconductor LM84
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Prefix: 'lm84'
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Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
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Datasheet: Publicly available at the National Semiconductor website
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* National Semiconductor LM90
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Prefix: 'lm90'
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Addresses scanned: I2C 0x4c
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Datasheet: Publicly available at the National Semiconductor website
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http://www.national.com/pf/LM/LM90.html
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* National Semiconductor LM89
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Prefix: 'lm89' (no auto-detection)
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Addresses scanned: I2C 0x4c and 0x4d
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Datasheet: Publicly available at the National Semiconductor website
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http://www.national.com/mpf/LM/LM89.html
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* National Semiconductor LM99
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Prefix: 'lm99'
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Addresses scanned: I2C 0x4c and 0x4d
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Datasheet: Publicly available at the National Semiconductor website
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http://www.national.com/pf/LM/LM99.html
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* National Semiconductor LM86
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Prefix: 'lm86'
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Addresses scanned: I2C 0x4c
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Datasheet: Publicly available at the National Semiconductor website
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http://www.national.com/mpf/LM/LM86.html
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* Analog Devices ADM1020
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Prefix: 'adm1020'
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Addresses scanned: I2C 0x4c - 0x4e
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Datasheet: Publicly available at the Analog Devices website
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* Analog Devices ADM1021
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Prefix: 'adm1021'
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Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
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Datasheet: Publicly available at the Analog Devices website
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* Analog Devices ADM1021A/ADM1023
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Prefix: 'adm1023'
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Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
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Datasheet: Publicly available at the Analog Devices website
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* Analog Devices ADM1032
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Prefix: 'adm1032'
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Addresses scanned: I2C 0x4c and 0x4d
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Datasheet: Publicly available at the ON Semiconductor website
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https://www.onsemi.com/PowerSolutions/product.do?id=ADM1032
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* Analog Devices ADT7461
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Prefix: 'adt7461'
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Addresses scanned: I2C 0x4c and 0x4d
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Datasheet: Publicly available at the ON Semiconductor website
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https://www.onsemi.com/PowerSolutions/product.do?id=ADT7461
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* Analog Devices ADT7461A
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Prefix: 'adt7461a'
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Addresses scanned: I2C 0x4c and 0x4d
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Datasheet: Publicly available at the ON Semiconductor website
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https://www.onsemi.com/PowerSolutions/product.do?id=ADT7461A
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* Analog Devices ADT7481
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Prefix: 'adt7481'
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Addresses scanned: I2C 0x4b and 0x4c
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Datasheet: Publicly available at the ON Semiconductor website
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https://www.onsemi.com/PowerSolutions/product.do?id=ADT7481
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* Analog Devices ADT7482
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Prefix: 'adt7482'
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Addresses scanned: I2C 0x4c
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Datasheet: Publicly available at the ON Semiconductor website
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https://www.onsemi.com/PowerSolutions/product.do?id=ADT7482
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* Analog Devices ADT7483A
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Prefix: 'adt7483a'
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Addresses scanned: I2C 0x18, 0x19, 0x1a, 0x29, 0x2a, 0x2b, 0x4c, 0x4d, 0x4e
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Datasheet: Publicly available at the ON Semiconductor website
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https://www.onsemi.com/PowerSolutions/product.do?id=ADT7483A
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* ON Semiconductor NCT1008
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Prefix: 'nct1008'
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Addresses scanned: I2C 0x4c and 0x4d
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Datasheet: Publicly available at the ON Semiconductor website
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https://www.onsemi.com/PowerSolutions/product.do?id=NCT1008
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* ON Semiconductor NCT210
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Prefix: 'adm1021'
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Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
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Datasheet: Publicly available at the ON Semiconductor website
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https://www.onsemi.com/PowerSolutions/product.do?id=NCT210
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* ON Semiconductor NCT214
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Prefix: 'nct214'
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Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
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Datasheet: Publicly available at the ON Semiconductor website
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https://www.onsemi.com/PowerSolutions/product.do?id=NCT214
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* ON Semiconductor NCT218
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Prefix: 'nct218'
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Addresses scanned: I2C 0x4c - 0x4d
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Datasheet: Publicly available at the ON Semiconductor website
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https://www.onsemi.com/PowerSolutions/product.do?id=NCT218
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* ON Semiconductor NCT72
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Prefix: 'nct72'
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Addresses scanned: I2C 0x4c - 0x4d
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Datasheet: Publicly available at the ON Semiconductor website
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https://www.onsemi.com/PowerSolutions/product.do?id=NCT72
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* Maxim MAX1617
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Prefix: 'max1617'
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Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
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Datasheet: Publicly available at the Maxim website
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* Maxim MAX1617A
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Prefix: 'max1617a'
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Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
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Datasheet: Publicly available at the Maxim website
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* Maxim MAX6642
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Prefix: 'max6642'
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Addresses scanned: I2C 0x48-0x4f
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Datasheet: Publicly available at the Maxim website
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http://datasheets.maxim-ic.com/en/ds/MAX6642.pdf
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* Maxim MAX6646
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Prefix: 'max6646'
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Addresses scanned: I2C 0x4d
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Datasheet: Publicly available at the Maxim website
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http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3497
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* Maxim MAX6647
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Prefix: 'max6646'
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Addresses scanned: I2C 0x4e
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Datasheet: Publicly available at the Maxim website
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http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3497
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* Maxim MAX6648
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Prefix: 'max6648'
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Addresses scanned: I2C 0x4c
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Datasheet: Publicly available at the Maxim website
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http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3500
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* Maxim MAX6649
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Prefix: 'max6646'
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Addresses scanned: I2C 0x4c
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Datasheet: Publicly available at the Maxim website
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http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3497
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* Maxim MAX6654
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Prefix: 'max6654'
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Addresses scanned: I2C 0x18, 0x19, 0x1a, 0x29, 0x2a, 0x2b,
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0x4c, 0x4d and 0x4e
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Datasheet: Publicly available at the Maxim website
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https://www.maximintegrated.com/en/products/sensors/MAX6654.html
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* Maxim MAX6657
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Prefix: 'max6657'
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Addresses scanned: I2C 0x4c
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Datasheet: Publicly available at the Maxim website
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http://www.maxim-ic.com/quick_view2.cfm/qv_pk/2578
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* Maxim MAX6658
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Prefix: 'max6657'
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Addresses scanned: I2C 0x4c
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Datasheet: Publicly available at the Maxim website
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http://www.maxim-ic.com/quick_view2.cfm/qv_pk/2578
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* Maxim MAX6659
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Prefix: 'max6659'
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Addresses scanned: I2C 0x4c, 0x4d, 0x4e
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Datasheet: Publicly available at the Maxim website
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http://www.maxim-ic.com/quick_view2.cfm/qv_pk/2578
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* Maxim MAX6680
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Prefix: 'max6680'
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Addresses scanned: I2C 0x18, 0x19, 0x1a, 0x29, 0x2a, 0x2b,
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0x4c, 0x4d and 0x4e
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Datasheet: Publicly available at the Maxim website
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http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3370
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* Maxim MAX6681
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Prefix: 'max6680'
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Addresses scanned: I2C 0x18, 0x19, 0x1a, 0x29, 0x2a, 0x2b,
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0x4c, 0x4d and 0x4e
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Datasheet: Publicly available at the Maxim website
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http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3370
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* Maxim MAX6692
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Prefix: 'max6648'
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Addresses scanned: I2C 0x4c
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Datasheet: Publicly available at the Maxim website
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http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3500
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* Maxim MAX6695
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Prefix: 'max6695'
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Addresses scanned: I2C 0x18
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Datasheet: Publicly available at the Maxim website
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http://www.maxim-ic.com/datasheet/index.mvp/id/4199
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* Maxim MAX6696
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Prefix: 'max6695'
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Addresses scanned: I2C 0x18, 0x19, 0x1a, 0x29, 0x2a, 0x2b,
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0x4c, 0x4d and 0x4e
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Datasheet: Publicly available at the Maxim website
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http://www.maxim-ic.com/datasheet/index.mvp/id/4199
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* Winbond/Nuvoton W83L771W/G
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Prefix: 'w83l771'
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Addresses scanned: I2C 0x4c
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Datasheet: No longer available
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* Winbond/Nuvoton W83L771AWG/ASG
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Prefix: 'w83l771'
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Addresses scanned: I2C 0x4c
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Datasheet: Not publicly available, can be requested from Nuvoton
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* Philips/NXP SA56004X
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Prefix: 'sa56004'
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Addresses scanned: I2C 0x48 through 0x4F
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Datasheet: Publicly available at NXP website
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http://ics.nxp.com/products/interface/datasheet/sa56004x.pdf
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* GMT G781
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Prefix: 'g781'
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Addresses scanned: I2C 0x4c, 0x4d
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Datasheet: Not publicly available from GMT
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* Texas Instruments TMP451
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Prefix: 'tmp451'
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Addresses scanned: I2C 0x4c
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Datasheet: Publicly available at TI website
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https://www.ti.com/litv/pdf/sbos686
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* Texas Instruments TMP461
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Prefix: 'tmp461'
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Addresses scanned: I2C 0x48 through 0x4F
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Datasheet: Publicly available at TI website
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https://www.ti.com/lit/gpn/tmp461
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* Philips NE1617, NE1617A
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Prefix: 'max1617' (probably detected as a max1617)
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Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
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Datasheets: Publicly available at the Philips website
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* Philips NE1618
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Prefix: 'ne1618'
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Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
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Datasheets: Publicly available at the Philips website
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* Genesys Logic GL523SM
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Prefix: 'gl523sm'
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Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
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Datasheet:
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* TI THMC10
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Prefix: 'thmc10'
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Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
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Datasheet: Publicly available at the TI website
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* Onsemi MC1066
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Prefix: 'mc1066'
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Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
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Datasheet: Publicly available at the Onsemi website
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Author: Jean Delvare <jdelvare@suse.de>
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Description
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-----------
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The LM90 is a digital temperature sensor. It senses its own temperature as
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well as the temperature of up to one external diode. It is compatible
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with many other devices, many of which are supported by this driver.
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The family of chips supported by this driver is derived from MAX1617.
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This chip as well as various compatible chips support a local and a remote
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temperature sensor with 8 bit accuracy. Later chips provide improved accuracy
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and other additional features such as hysteresis and temperature offset
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registers.
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Note that there is no easy way to differentiate between the MAX6657,
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MAX6658 and MAX6659 variants. The extra features of the MAX6659 are only
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supported by this driver if the chip is located at address 0x4d or 0x4e,
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or if the chip type is explicitly selected as max6659.
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The MAX6680 and MAX6681 only differ in their pinout, therefore they obviously
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can't (and don't need to) be distinguished.
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The different chipsets of the family are not strictly identical, although
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very similar. For reference, here comes a non-exhaustive list of specific
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features:
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LM84:
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* 8 bit sensor resolution
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ADM1020, ADM1021, GL523SM, MAX1617, NE1617, NE1617A, THMC10:
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* 8 bit sensor resolution
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* Low temperature limits
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NCT210, NE1618:
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* 11 bit sensor resolution for remote temperature sensor
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* Low temperature limits
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ADM1021A, ADM1023:
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* Temperature offset register for remote temperature sensor
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* 11 bit resolution for remote temperature sensor
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* Low temperature limits
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LM90:
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* 11 bit resolution for remote temperature sensor
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* Temperature offset register for remote temperature sensor
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* Low and critical temperature limits
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* Configurable conversion rate
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* Filter and alert configuration register at 0xBF.
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* ALERT is triggered by temperatures over critical limits.
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LM86 and LM89:
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* Same as LM90
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* Better external channel accuracy
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LM99:
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* Same as LM89
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* External temperature shifted by 16 degrees down
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ADM1032:
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* Consecutive alert register at 0x22.
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* Conversion averaging.
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* Up to 64 conversions/s.
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* ALERT is triggered by open remote sensor.
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* SMBus PEC support for Write Byte and Receive Byte transactions.
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ADT7461, ADT7461A, NCT1008:
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* Extended temperature range (breaks compatibility)
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* Lower resolution for remote temperature
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* SMBus PEC support for Write Byte and Receive Byte transactions.
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* 10 bit temperature resolution
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ADT7481, ADT7482, ADT7483:
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* Temperature offset register
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* SMBus PEC support
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* 10 bit temperature resolution for external sensors
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* Two remote sensors
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* Selectable address (ADT7483)
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MAX6642:
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* No critical limit register
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* Conversion rate not configurable
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* Better local resolution (10 bit)
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* 10 bit external sensor resolution
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MAX6646, MAX6647, MAX6649:
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* Better local resolution
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* Extended range unsigned external temperature
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MAX6648, MAX6692:
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* Better local resolution
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* Unsigned temperature
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MAX6654, MAX6690:
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* Better local resolution
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* Selectable address
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* Remote sensor type selection
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* Extended temperature range
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* Extended resolution only available when conversion rate <= 1 Hz
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MAX6657 and MAX6658:
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* Better local resolution
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* Remote sensor type selection
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MAX6659:
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* Better local resolution
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* Selectable address
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* Second critical temperature limit
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* Remote sensor type selection
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MAX6680 and MAX6681:
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* Selectable address
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* Remote sensor type selection
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MAX6695 and MAX6696:
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* Better local resolution
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* Selectable address (max6696)
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* Second critical temperature limit
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* Two remote sensors
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W83L771W/G
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* The G variant is lead-free, otherwise similar to the W.
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* Filter and alert configuration register at 0xBF
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* Moving average (depending on conversion rate)
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W83L771AWG/ASG
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* Successor of the W83L771W/G, same features.
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* The AWG and ASG variants only differ in package format.
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* Diode ideality factor configuration (remote sensor) at 0xE3
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SA56004X:
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* Better local resolution
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All temperature values are given in degrees Celsius. Resolution
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is 1.0 degree for the local temperature, 0.125 degree for the remote
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temperature, except for the MAX6654, MAX6657, MAX6658 and MAX6659 which have
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a resolution of 0.125 degree for both temperatures.
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Each sensor has its own high and low limits, plus a critical limit.
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Additionally, there is a relative hysteresis value common to both critical
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values. To make life easier to user-space applications, two absolute values
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are exported, one for each channel, but these values are of course linked.
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|
Only the local hysteresis can be set from user-space, and the same delta
|
|
applies to the remote hysteresis.
|
|
|
|
The lm90 driver will not update its values more frequently than configured with
|
|
the update_interval attribute; reading them more often will do no harm, but will
|
|
return 'old' values.
|
|
|
|
SMBus Alert Support
|
|
-------------------
|
|
|
|
This driver has basic support for SMBus alert. When an alert is received,
|
|
the status register is read and the faulty temperature channel is logged.
|
|
|
|
The Analog Devices chips (ADM1032, ADT7461 and ADT7461A) and ON
|
|
Semiconductor chips (NCT1008) do not implement the SMBus alert protocol
|
|
properly so additional care is needed: the ALERT output is disabled when
|
|
an alert is received, and is re-enabled only when the alarm is gone.
|
|
Otherwise the chip would block alerts from other chips in the bus as long
|
|
as the alarm is active.
|
|
|
|
PEC Support
|
|
-----------
|
|
|
|
The ADM1032 is the only chip of the family which supports PEC. It does
|
|
not support PEC on all transactions though, so some care must be taken.
|
|
|
|
When reading a register value, the PEC byte is computed and sent by the
|
|
ADM1032 chip. However, in the case of a combined transaction (SMBus Read
|
|
Byte), the ADM1032 computes the CRC value over only the second half of
|
|
the message rather than its entirety, because it thinks the first half
|
|
of the message belongs to a different transaction. As a result, the CRC
|
|
value differs from what the SMBus master expects, and all reads fail.
|
|
|
|
For this reason, the lm90 driver will enable PEC for the ADM1032 only if
|
|
the bus supports the SMBus Send Byte and Receive Byte transaction types.
|
|
These transactions will be used to read register values, instead of
|
|
SMBus Read Byte, and PEC will work properly.
|
|
|
|
Additionally, the ADM1032 doesn't support SMBus Send Byte with PEC.
|
|
Instead, it will try to write the PEC value to the register (because the
|
|
SMBus Send Byte transaction with PEC is similar to a Write Byte transaction
|
|
without PEC), which is not what we want. Thus, PEC is explicitly disabled
|
|
on SMBus Send Byte transactions in the lm90 driver.
|
|
|
|
PEC on byte data transactions represents a significant increase in bandwidth
|
|
usage (+33% for writes, +25% for reads) in normal conditions. With the need
|
|
to use two SMBus transaction for reads, this overhead jumps to +50%. Worse,
|
|
two transactions will typically mean twice as much delay waiting for
|
|
transaction completion, effectively doubling the register cache refresh time.
|
|
I guess reliability comes at a price, but it's quite expensive this time.
|
|
|
|
So, as not everyone might enjoy the slowdown, PEC is disabled by default and
|
|
can be enabled through sysfs. Just write 1 to the "pec" file and PEC will be
|
|
enabled. Write 0 to that file to disable PEC again.
|