The LKM04832 "CLKOUT" clock implements a mux with a set_parent hook, but
doesn't provide a determine_rate implementation.
This is a bit odd, since set_parent() is there to, as its name implies,
change the parent of a clock. However, the most likely candidate to
trigger that parent change is a call to clk_set_rate(), with
determine_rate() figuring out which parent is the best suited for a
given rate.
The other trigger would be a call to clk_set_parent(), but it's far less
used, and it doesn't look like there's any obvious user for that clock.
So, the set_parent hook is effectively unused, possibly because of an
oversight. However, it could also be an explicit decision by the
original author to avoid any reparenting but through an explicit call to
clk_set_parent().
The latter case would be equivalent to setting the flag
CLK_SET_RATE_NO_REPARENT, together with setting our determine_rate hook
to __clk_mux_determine_rate(). Indeed, if no determine_rate
implementation is provided, clk_round_rate() (through
clk_core_round_rate_nolock()) will call itself on the parent if
CLK_SET_RATE_PARENT is set, and will not change the clock rate
otherwise.
And if it was an oversight, then we are at least explicit about our
behavior now and it can be further refined down the line.
Since the CLK_SET_RATE_NO_REPARENT flag was already set though, it seems
unlikely.
Reviewed-by: Liam Beguin <liambeguin@gmail.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/20221018-clk-range-checks-fixes-v4-16-971d5077e7d2@cerno.tech
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Fix syntax generating the following kernel-doc warnings:
drivers/clk/clk-lmk04832.c:189: warning: cannot understand function prototype: 'struct lmk04832_device_info '
drivers/clk/clk-lmk04832.c:193: warning: Function parameter or member 'pid' not described in 'lmk04832_device_info'
drivers/clk/clk-lmk04832.c:193: warning: Function parameter or member 'maskrev' not described in 'lmk04832_device_info'
drivers/clk/clk-lmk04832.c:193: warning: Function parameter or member 'num_channels' not described in 'lmk04832_device_info'
drivers/clk/clk-lmk04832.c:193: warning: Function parameter or member 'vco0_range' not described in 'lmk04832_device_info'
drivers/clk/clk-lmk04832.c:193: warning: Function parameter or member 'vco1_range' not described in 'lmk04832_device_info'
drivers/clk/clk-lmk04832.c:420: warning: No description found for return value of 'lmk04832_check_vco_ranges'
drivers/clk/clk-lmk04832.c:459: warning: No description found for return value of 'lmk04832_calc_pll2_params'
Signed-off-by: Liam Beguin <liambeguin@gmail.com>
Link: https://lore.kernel.org/r/20221120030257.531153-5-liambeguin@gmail.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
The digital delay allows outputs to be delayed from 8 to 1023 VCO
cycles. The delay step can be as small as half the period of the clock
distribution path. For example, a 3.2-GHz VCO frequency results in
156.25-ps steps. The digital delay value takes effect on the clock
output phase after a SYNC event.
This is required to support JESD204B subclass 1.
Signed-off-by: Liam Beguin <lvb@xiphos.com>
Link: https://lore.kernel.org/r/20210423004057.283926-3-liambeguin@gmail.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
