lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Fri, 22 Feb 2019 10:12:33 -0800
From:   Stephen Boyd <>
Subject: Re: [PATCH v2 08/14] clk: qcom: hfpll: CLK_IGNORE_UNUSED

Quoting Jorge Ramirez-Ortiz (2019-01-28 10:32:55)
> When COMMON_CLK_DISABLED_UNUSED is set, in an effort to save power and
> to keep the software model of the clock in line with reality, the
> framework transverses the clock tree and disables those clocks that
> were enabled by the firmware but have not been enabled by any device
> driver.
> If CPUFREQ is enabled, early during the system boot, it might attempt
> to change the CPU frequency ("set_rate"). If the HFPLL is selected as
> a provider, it will then change the rate for this clock.
> As boot continues, clk_disable_unused_subtree will run. Since it wont
> find a valid counter (enable_count) for a clock that is actually
> enabled it will attempt to disable it which will cause the CPU to
> stop. Notice that in this driver, calls to check whether the clock is
> enabled are routed via the is_enabled callback which queries the
> hardware.
> The following commit, rather than marking the clock critical and
> forcing the clock to be always enabled, addresses the above scenario
> making sure the clock is not disabled but it continues to rely on the
> firmware to enable the clock.
> Co-developed-by: Niklas Cassel <>
> Signed-off-by: Niklas Cassel <>
> Signed-off-by: Jorge Ramirez-Ortiz <>
> ---
>  drivers/clk/qcom/hfpll.c | 1 +
>  1 file changed, 1 insertion(+)
> diff --git a/drivers/clk/qcom/hfpll.c b/drivers/clk/qcom/hfpll.c
> index 0ffed0d..9d92f5d 100644
> --- a/drivers/clk/qcom/hfpll.c
> +++ b/drivers/clk/qcom/hfpll.c
> @@ -58,6 +58,7 @@ static int qcom_hfpll_probe(struct platform_device *pdev)
>                 .parent_names = (const char *[]){ "xo" },
>                 .num_parents = 1,
>                 .ops = &clk_ops_hfpll,
> +               .flags = CLK_IGNORE_UNUSED,

Please put some sort of similar comment in the code so we can find it
without git history digging.

Powered by blists - more mailing lists