The DCCFreq value is used to obtain the DC offset canceller cut-off frequency. Upon device power reset, the bits 7-5 of the RegRxBw register that represent the DCCFreq setting are set to 0x4, which evaluates the cut-off frequency to be 1% of RxBw. In the current implementation, first, there is no configuration variable defined in the struct pi433_rx_cfg for the user to set this value as part of the UAPI. Second, the code simply ignores the value of DCC setting and allows it to never change. As per the RFM69HCW tech specs, the default value for DCC frequency is recommended to be 4% of the RxBw; which requires the DCC setting bits to be set to 010. So allow the DCC setting to change to recommended / default value for improved rx sensitivity. Signed-off-by: Deepak R Varma <drv@xxxxxxxxx> --- Please Note: The proposed change is compile tested only. I am unable to perform device based testing in the absence of the hardware, both the RasPi board and the Pi433 device. Please let me know if it is necessary for me to test such patches on the real device myself. I will stop sending the patches till I have the hardware to test them. Thanks. drivers/staging/pi433/rf69.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/staging/pi433/rf69.c b/drivers/staging/pi433/rf69.c index 8c7fab6a46bb..8468d4717dd0 100644 --- a/drivers/staging/pi433/rf69.c +++ b/drivers/staging/pi433/rf69.c @@ -465,6 +465,13 @@ static int rf69_set_bandwidth_intern(struct spi_device *spi, u8 reg, // read old value bandwidth = rf69_read_reg(spi, reg); + /* DCC setting bits [7-5] are set to 0x4 on reset. Since there is no user + * input available in the rx config struct, we should set it to default + * or the recommended value as per the technical specification. + */ + if ((bandwidth >> 5) == 0x4) + bandwidth = bandwidth & BW_DCC_4_PERCENT; + // "delete" mantisse and exponent = just keep the DCC setting bandwidth = bandwidth & MASK_BW_DCC_FREQ; -- 2.34.1
