linux-kernel - Re: [PATCH 5/5] clk: qcom: hfpll: CLK_IGNORE

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Date:   Mon, 09 Sep 2019 03:23:10 -0700
From:   Stephen Boyd <sboyd@...nel.org>
To:     agross@...nel.org, jorge.ramirez-ortiz@...aro.org,
        mturquette@...libre.com
Cc:     bjorn.andersson@...aro.org, niklas.cassel@...aro.org,
        linux-arm-msm@...r.kernel.org, linux-clk@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/5] clk: qcom: hfpll: CLK_IGNORE_UNUSED

Quoting Jorge Ramirez-Ortiz (2019-08-26 09:45:10)
> 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 <niklas.cassel@...aro.org>
> Signed-off-by: Niklas Cassel <niklas.cassel@...aro.org>
> Signed-off-by: Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@...aro.org>
> Reviewed-by: Bjorn Andersson <bjorn.andersson@...aro.org>
> ---

Also this one. Seems fine to merge immediately vs the ones that do some
DT trickery.