The si544 driver had a rounding problem that using the result of clk_round_rate
may set the clock to yet another rate, for example:
clk_round_rate(195000000) = 194999999
clk_round_rate(194999999) = 194999998
Clients would expect that after clk_set_rate(clk, freq2=clk_round_rate(clk, freq)) the
chip will be running at exactly freq2.
The problem was in the calculation of the feedback divider, it was always rounded
down instead of to the nearest possible VCO value.
After this change, the following holds true for any supported frequency:
actual_freq = clk_round_rate(clk, freq);
clk_set_rate(clk, actual_freq);
clk_round_rate(clk, actual_freq) == actual_freq && clk_get_rate(clk) == actual_freq
Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>
Fixes: 953cc3e811 ("clk: Add driver for the si544 clock generator chip")
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
This patch adds the driver and devicetree documentation for the
Silicon Labs SI544 clock generator chip. This is an I2C controlled
oscillator capable of generating clock signals ranging from 200kHz
to 1500MHz.
Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>
[sboyd: assign max_freq to 0 in is_valid_frequency() to squelch warning]
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Mike Looijmans