Kernel/linux-next
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git synced 2025-01-17 13:58:46 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

staging: pi433: fix frequency deviation check

Browse Source 
rf69 datasheet states that frequency deviation must exceed 600 Hz but
also that frequency deviation + (bitrate / 2) should be less than equal
to 500 kHz to ensure proper modulation.

This patch validates that both conditions are met so RF intersymbol
interference is less likely to happen due to misconfiguration of the uC

Signed-off-by: Paulo Miguel Almeida <paulo.miguel.almeida.rodenas@gmail.com>
Link: https://lore.kernel.org/r/20220103222334.GA6814@mail.google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Paulo Miguel Almeida 2022-01-04 11:23:34 +13:00 committed by Greg Kroah-Hartman
parent b33721bacc
commit 70d8e20c24
1 changed files with 15 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
drivers/staging/pi433/rf69.c
View File

@ -255,13 +255,25 @@ int rf69_set_deviation(struct spi_device *spi, u32 deviation)
int retval;
u64 f_reg;
u64 f_step;
u32 bit_rate_reg;
u32 bit_rate;
u8 msb;
u8 lsb;
u64 factor = 1000000; // to improve precision of calculation
// TODO: Dependency to bitrate
if (deviation < 600 || deviation > 500000) {
dev_dbg(&spi->dev, "set_deviation: illegal input param");
// calculate bit rate
bit_rate_reg = rf69_read_reg(spi, REG_BITRATE_MSB) << 8;
bit_rate_reg |= rf69_read_reg(spi, REG_BITRATE_LSB);
bit_rate = F_OSC / bit_rate_reg;
/*
* frequency deviation must exceed 600 Hz but not exceed
* 500kHz when taking bitrate dependency into consideration
* to ensure proper modulation
*/
if (deviation < 600 || (deviation + (bit_rate / 2)) > 500000) {
dev_dbg(&spi->dev,
"set_deviation: illegal input param: %u", deviation);
return -EINVAL;
}