clk: Remove WARN_ON NULL parent in clk_core_init_rate_req()

If a clock has CLK_SET_RATE_PARENT, but core->parent is NULL (most
likely because it's orphan), callers of clk_core_init_rate_req() will
blindly call this function leading to a very verbose warning.

Since it's a fairly common situation, let's just remove the WARN_ON but
keep the check that prevents us from dereferencing the pointer.

Interestingly, it fixes a regression on the Mediatek MT8195 where the
GPU would stall during a clk_set_rate for its main clock. We couldn't
come up with a proper explanation since the condition is essentially the
same.

It was then assumed that it could be timing related since printing the
warning stacktrace takes a while, but we couldn't replicate the failure
by using fairly large (10ms) mdelays.

Fixes: 262ca38f4b6e ("clk: Stop forwarding clk_rate_requests to the parent")
Reported-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/20221018-clk-range-checks-fixes-v1-1-f3ef80518140@cerno.tech
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index c3c3f8c072588d2a3581e7af7cad80115ffb081d..37d623c7b73b7a2c8e9a392258fc98907c174bdd 100644 (file)
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -1459,7 +1459,7 @@ static void clk_core_init_rate_req(struct clk_core * const core,
 {
        struct clk_core *parent;
 
-       if (WARN_ON(!core || !req))
+       if (!core || WARN_ON(!req))
                return;
 
        memset(req, 0, sizeof(*req));