Improve Pi 5 I2C bus timing #5802
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The i2c-designware driver supports reading precise timing values from ACPI, but the Device Tree support relies on a combination of standard rise and fall times and hard-coded minimum timings. The result of this is that it is difficult to get optimum timings, particularly given that the values are bus speed-specific and only one set can be stored in DT at a time. Add support for initialisation from DT that is similar to that for ACPI. Signed-off-by: Phil Elwell <phil@raspberrypi.com>
Signed-off-by: Phil Elwell <phil@raspberrypi.com>
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kernel: ARM: dts: bcm2712-rpi-5-b: Allow RTC to be disabled See: raspberrypi/linux#5803 kernel: Improve Pi 5 I2C bus timing See: raspberrypi/linux#5802 kernel: input: edt-ft5x06: Correct prefix length in snprintf See: raspberrypi/linux#5798 kernel: Allow IMX477 and IMX296 to be always on, to simplify multi-camera sync See: raspberrypi/linux#5774
popcornmix
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kernel: ARM: dts: bcm2712-rpi-5-b: Allow RTC to be disabled See: raspberrypi/linux#5803 kernel: Improve Pi 5 I2C bus timing See: raspberrypi/linux#5802 kernel: input: edt-ft5x06: Correct prefix length in snprintf See: raspberrypi/linux#5798 kernel: Allow IMX477 and IMX296 to be always on, to simplify multi-camera sync See: raspberrypi/linux#5774
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It has been observed that the Pi 5 I2C buses don't reach the expected speeds. That is down to the absence of accurate bus timings, with the defaults being pessimistic. Add a way of configuring bus-speed specific timings via Device Tree, and a set of tuned values that should give accurate 100kHz, 400kHz and 1MHz speeds.
See: #5792