15.09.2021 21:31, Chanwoo Choi пишет:

On 21. 9. 15. 오후 12:51, Chanwoo Choi wrote:

quoted

Hi,

On 21. 9. 13. 오전 3:44, Dmitry Osipenko wrote:

quoted

EMC clock is always-on and can't be zero. Check whether clk_round_rate()
returns zero rate and error out if it does. It can return zero if clock
tree isn't initialized properly.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
  drivers/devfreq/tegra30-devfreq.c | 4 ++--
  1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/devfreq/tegra30-devfreq.c

b/drivers/devfreq/tegra30-devfreq.c
index d83fdc2713ed..65ecf17a36f4 100644

--- a/drivers/devfreq/tegra30-devfreq.c
+++ b/drivers/devfreq/tegra30-devfreq.c

@@ -891,9 +891,9 @@ static int tegra_devfreq_probe(struct

platform_device *pdev)
          return err;
      rate = clk_round_rate(tegra->emc_clock, ULONG_MAX);
-    if (rate < 0) {
+    if (rate <= 0) {
          dev_err(&pdev->dev, "Failed to round clock rate: %ld\n",
rate);
-        return rate;
+        return rate ?: -EINVAL;

If rate is 0, It doesn't return and fall-through? even if print the
error message. 'return rate ?: -EINVAL;' style is strange for me
because it doesn't specify the 'return value' when rate is true.

It's not clear to me what do you mean by "return and fall-through".

It specifies the 'return value' when rate is true. It's a short form of
"rate ? rate : -EINVAL".

The final returned value will be printed by the driver's core. The value
returned by clk_round_rate() is important here since it tells the reason
of the error.

https://elixir.bootlin.com/linux/v5.15-rc1/source/drivers/base/dd.c#L533