[PATCH v2 1/3] clk: Initialize orphan req_rate

[Maxime Ripard <maxime@cerno.tech>]

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>
---
 drivers/clk/clk.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 9bc8bf434b94..915a2fa363b1 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -3479,6 +3479,19 @@ static void clk_core_reparent_orphans_nolock(void)
 			__clk_set_parent_after(orphan, parent, NULL);
 			__clk_recalc_accuracies(orphan);
 			__clk_recalc_rates(orphan, 0);
+
+			/*
+			 * If the clock doesn't have .recalc_rate (so
+			 * wouldn't affect the parent rate) and is
+			 * orphan when it's registered, the
+			 * __clk_init_parent will set the initial
+			 * req_rate to 0.
+			 *
+			 * req_rate is then used by clk_set_rate_range
+			 * and clk_put to trigger a clk_set_rate call
+			 * whenever the boundaries are modified.
+			 */
+			orphan->req_rate = orphan->rate;
 		}
 	}
 }
-- 
2.35.1