From: Maxime Ripard maxime@cerno.tech
[ Upstream commit 5f7e2af00807f2117650e711a58b7f0e986ce1df ]
When registering a clock that doesn't have a recalc_rate implementation, and doesn't have its parent registered yet, we initialize the clk_core rate and 'req_rate' fields to 0.
The rate field is later updated when the parent is registered in clk_core_reparent_orphans_nolock() using __clk_recalc_rates(), but the 'req_rate' field is never updated.
This leads to an issue in clk_set_rate_range() and clk_put(), since those functions will call clk_set_rate() with the content of 'req_rate' to provide drivers with the opportunity to change the rate based on the new boundaries. In this case, we would call clk_set_rate() with a rate of 0, effectively enforcing the minimum allowed for this clock whenever we would call one of those two functions, even though the actual rate might be within range.
Let's fix this by setting 'req_rate' in clk_core_reparent_orphans_nolock() with the rate field content just updated by the call to __clk_recalc_rates().
Fixes: 1c8e600440c7 ("clk: Add rate constraints to clocks") Reported-by: Dmitry Osipenko dmitry.osipenko@collabora.com Tested-by: Dmitry Osipenko dmitry.osipenko@collabora.com # T30 Nexus7 Signed-off-by: Maxime Ripard maxime@cerno.tech Link: https://lore.kernel.org/r/20220325161144.1901695-2-maxime@cerno.tech [sboyd@kernel.org: Reword comment] Signed-off-by: Stephen Boyd sboyd@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/clk/clk.c | 13 +++++++++++++ 1 file changed, 13 insertions(+)
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index 32fd2853e8b2..5cef73a85901 100644 --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c @@ -3410,6 +3410,19 @@ static void clk_core_reparent_orphans_nolock(void) __clk_set_parent_after(orphan, parent, NULL); __clk_recalc_accuracies(orphan); __clk_recalc_rates(orphan, 0); + + /* + * __clk_init_parent() will set the initial req_rate to + * 0 if the clock doesn't have clk_ops::recalc_rate and + * is an orphan when it's registered. + * + * 'req_rate' is used by clk_set_rate_range() and + * clk_put() to trigger a clk_set_rate() call whenever + * the boundaries are modified. Let's make sure + * 'req_rate' is set to something non-zero so that + * clk_set_rate_range() doesn't drop the frequency. + */ + orphan->req_rate = orphan->rate; } } }